Terrain Awareness and Warning System

SUMMARY: The Federal Aviation Administration (FAA) proposes to issue

operating rules that would prohibit operation of turbine-powered U.S.-

registered airplanes type certificated to have six or more passenger

seats, exclusive of pilot and copilot seating, unless that airplane is

equipped with an FAA-approved terrain awareness and warning system

(also referred to as an enhanced ground proximity warning system). This

proposal would affect aircraft operated under parts 91, 121 and 135.

Because operators under part 125 and operators of U.S.-registered

airplanes under part 129 must comply with part 91, they would also have

to meet this requirement. This change is needed because there have been

several accident investigations and studies that have shown a need to

expand the safety benefits of ground proximity warning systems to

certain additional operations. In addition, these investigations and

studies have shown that there is a need to increase the warning times

and situational awareness of flight crews to decrease the risk of

controlled flight into terrain accidents.

DATES: Comments must be received by November 24, 1998.

ADDRESSES: Comments on this notice should be mailed, in triplicate to:

Federal Aviation Administration, Office of the Chief Counsel,

Attention: Rules Docket (AGC-200), Docket No. 29312, 800 Independence

Avenue, SW., Washington, DC 20591. Comments may also be sent

electronically to the Rules Docket by using the following Internet

address: [email protected]. Comments must be marked Docket No.

29312. Comments may be examined in the Rules Docket in Room 915G on

weekdays between 8:30 a.m. and 5:00 p.m., except on Federal holidays.

FOR FURTHER INFORMATION CONTACT: Manuel Macedo, Aircraft Engineering

Division, AIR-100, Aircraft Certification Service, Federal Aviation

Administration, 800 Independence Avenue, SW., Washington, DC 20591;

Telephone: (202) 267-9566.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in this proposed

rulemaking by submitting such written data, views, or arguments as they

may desire. Comments relating to the environmental, energy, federalism,

or economic impact that may result from adopting the proposals in this

notice are also invited. Comments that provide the factual basis

supporting the views and suggestions presented are particularly helpful

in developing reasoned regulatory decisions. Communications should

identify the regulatory docket number and be submitted in triplicate to

the above specified address. All communications and a report

summarizing any substantive public contact with FAA personnel

concerning this rulemaking will be filed in the docket. The docket is

available for public inspection both before and after the closing date

for receiving comments.

Before taking any final action on this proposal, the Administrator

will consider all comments made on or before the closing date for

comments, and the proposal may be changed in light of the comments

received.

The FAA will acknowledge receipt of a comment if the commenter

includes a self-addressed, stamped postcard with the comment. The

postcard should be marked ``Comments to Docket No. 29312.'' When the

comment is received by the FAA, the postcard will be dated and returned

to the commenter.

Availability of the Notice

Any person may obtain a copy of this notice of proposed rulemaking

(NPRM) by submitting a request to the Federal Aviation Administration,

Office of Rulemaking, 800 Independence Avenue SW., Washington, DC

20591, or by calling (202) 267-9677. Communications must identify the

notice number of this NPRM. Persons interested in being placed on a

mailing list for future FAA NPRM's should request a copy of Advisory

Circular No. 11-2A, Notice of Proposed Rulemaking Distribution System,

which describes application procedures.

An electronic copy of this document may be downloaded using a modem

and suitable communications software from the FAA regulations section

of the Fedworld electronic bulletin board service (telephone: 703-321-

3339). Internet users may reach the FAA's web page at http://

www.faa.gov or the Federal Register's webpage at http://

www.access.gpo.gov/NARA/index.html for access to recently published

rulemaking documents.

Background

Beginning in the early 1970's, a number of studies looked at the

occurrence of ``controlled flight into terrain'' (CFIT)-type accidents,

where a properly functioning airplane under the control of a fully

qualified and certificated crew is flown into terrain (or water or

obstacles) with no apparent awareness on the part of the crew.

Findings from these studies indicated that many such accidents

could have been avoided if a warning device called a ground proximity

warning system (GPWS) was used. As a result of these studies and

recommendations from the National Transportation Safety Board (NTSB),

in 1974 the FAA required all part 121 certificate holders (i.e., those

operating large turbine-powered airplanes) and some part 135

certificate holders (i.e., those operating large turbojet airplanes) to

install Technical Standard Order (TSO) approved GPWS equipment

(Secs. 121.360 and 135.153). (39 FR 44439, December 18, 1974).

In 1978 the FAA extended the GPWS requirement to part 135

certificate holders operating smaller airplanes: turbojet-powered

airplanes with 10 or more passenger seats. These operators were

required to install TSO-approved GPWS equipment or alternative ground

proximity advisory systems that provide routine altitude callouts

whether or not there is any imminent danger (Sec. 135.153). (43 FR

28176, June 29, 1978). This requirement was considered necessary

because of the complexity, size, speed, and flight performance

characteristics of these airplanes. The GPWS equipment was considered

essential in helping the pilots of these airplanes to regain altitude

quickly and avoid what could have been a CFIT-type accident.

Installation of GPWS's or alternative FAA-approved advisory systems

was not required on turbo-propeller powered (turboprop) airplanes

operated under part 135 because, at that time, the general consensus

was that the performance characteristics of turboprop airplanes made

them less susceptible to CFIT accidents. For example, it was thought

that turboprop airplanes had a greater ability to respond quickly in

situations where altitude control was inadvertently neglected, as

compared to turbojet airplanes. However later studies, including

investigations by the NTSB, analyzed CFIT accidents involving turboprop

airplanes and found that many of these accidents could have been

avoided if GPWS equipment had been used.

[[Page 45629]]

Some of these studies also compared the effectiveness of the

alternative ground proximity advisory system to the GPWS. GPWS was

found to be superior in that it would warn only when necessary, provide

maximum warning time with minimal unwanted alarms, and use command-type

warnings.

Based on these reports and NTSB recommendations, in 1992 the FAA

amended Sec. 135.153 to require GPWS equipment on all turbine-powered

airplanes with 10 or more passenger seats. (57 FR 9944, March 20,

1992).

NTSB Recommendations

Following the investigation of a CFIT accident south of Dulles

International Airport on June 18, 1994, involving a Learjet 25D in

which there were 12 fatalities, the NTSB recommended (Recommendation A-

95-35) that the FAA mandate that all turbojet-powered airplanes

equipped with six or more passenger seats have an operating ground

proximity warning system installed. That recommendation also made

reference to an earlier, similar NTSB recommendation (Recommendation A-

92-055) resulting from a 1991 CFIT accident involving a Beechjet 400.

Both planes were corporate jets flying under part 91 and were not

required to have GPWS equipment installed.

More recently, the NTSB issued Recommendation A-96-101, based on

its investigation of a CFIT accident northeast of Cali, Colombia, on

December 20, 1995, involving an American Airlines Boeing 757 airplane

operating under part 121, which resulted in 159 fatalities. The NTSB

recommended that the FAA examine the effectiveness of enhanced ground

proximity warning equipment (described in the following section), and

if found effective, require all transport-category aircraft to be

equipped with this equipment. Although the accident airplane was

equipped with the mandatory GPWS, the GPWS did not provide the warning

in time for the crew to successfully avoid the mountainous terrain.

Terrain Awareness and Warning System (Enhanced Ground Proximity

Warning System)

Advances in terrain mapping technology have permitted the

development of a new type of ground proximity warning system that

provides greater situational awareness for flight crews. The FAA has

approved certain installations of this type of equipment, known as the

enhanced ground proximity warning system (EGPWS). However, in this

NPRM, the FAA is using the broader term ``terrain awareness and warning

system'' (TAWS) because the FAA expects that a variety of systems may

be developed in the near future that would meet the improved standards

being proposed in this NPRM.

TAWS improves on existing systems by providing the flight crew

automatic advanced aural and visual warning of impending terrain, much

earlier warning, forward looking capability, and operability in landing

configuration. These improvements provide more time for the flight crew

to make smoother and gradual corrective action. These functions are

more fully described under ``Functions and Approval of TAWS.''

Volpe National Transportation Systems Center Studies

In recent years, the FAA commissioned several studies by DOT's

Volpe National Transportation Systems Center (VNTSC) to examine the

effectiveness of GPWS and EGPWS in preventing CFIT accidents in various

aircraft categories and operations. These are described below.

Part 91 Study

In 1996, the FAA commissioned VNTSC to consider the installation of

current GPWS or EGPWS on all part 91 turbine-powered airplanes of 6 or

more passenger seats. Although NTSB Recommendation A-95-35 addressed

only turbojets, the FAA expanded the study focus to include all

turbine-powered airplanes because of the results of the previous

studies and rulemaking discussed earlier.

Forty-four CFIT accidents that occurred between 1985 and 1994 were

studied. The airplanes involved had from six to ten passenger seats and

were operating under part 91. Eleven were turbojets and 33 were

turboprops. Because these flights were not conducted under parts 121 or

135, GPWS was not required and none of the airplanes had GPWS

installed. By using computer modeling techniques, VNTSC came to the

following conclusions: (1) GPWS meeting TSO-C92 could have avoided 33

of the 44 (75%) accidents and 96 fatalities; and (2) EGPWS could have

avoided 42 of the 44 (95%) accidents and 126 fatalities. The EGPWS

evaluated in the Volpe studies would meet the TAWS requirements

proposed in this NPRM. A more detailed analysis is included in FAA

study DOT-TSC-FA6D1-96-01, Investigation of Controlled Flight Into

Terrain, which is included in the public docket for this rulemaking, or

can be obtained by contacting the Aircraft Engineering Division, AIR-

100, Aircraft Certification Service, Federal Aviation Administration,

800 Independence Avenue, SW., Washington, DC 20591; Telephone: (202)

267-9566.

Part 121/135 Study

Later in 1996, the FAA commissioned VNTSC for a second study

focusing on a retrofit of GPWS with EGPWS on airplanes operated under

part 121 and part 135. This study documents an investigation of CFIT

aircraft accidents involving aircraft flying under part 121 and 135

flight rules, or their foreign equivalents, and evaluating the

potential for accident prevention by EGPWS.

There were over 100 fatal CFIT accidents worldwide during the study

period of 1985 to 1995. A list of 47 domestic and 104 foreign accidents

of aircraft with characteristics similar to those that would be covered

by the proposed rule was compiled. Of these totals, 38 domestic

accidents and 96 foreign accidents involved fatalities. Due to resource

constraints, detailed analysis of all these accidents was not possible.

The staff of the VNTSC developed a methodology and scheme for selecting

a representative sample for detailed study and analysis. While not an

exhaustive compilation of all CFIT accidents, it represents an effort

to review the characteristics of most major CFIT accidents. From this

process nine accidents were selected for detailed analysis worldwide.

Analysis showed that four of the nine accidents (44%) should have

been prevented by the basic GPWS equipment that had been installed.

However, in two cases the GPWS equipment was either disconnected or it

malfunctioned. In the other two cases, poor flight crew coordination

led to inaction following the GPWS warning, rather than decisive

recovery maneuvers, until impact could not be avoided.

In contrast, EGPWS warning times would have been more than the

warning time of GPWS (which was assumed by VNTSC to be 12-15 seconds)

in all nine cases. In seven, warning times expected with EGPWS exceeded

those of GPWS by over 20 seconds; two of these cases involved

differences of over one minute. In general, EGPWS should have provided

an additional margin in which flight crews could assess their

situation, discover errors, regain situational awareness, and take

appropriate action before impact. In only one case was an assumed EGPWS

warning duration only slightly above the 12-15 second minimum. In this

case it can be argued that if the visual forward looking terrain

[[Page 45630]]

display in EGPWS had been installed, it may have prevented the pilot's

fatal wrong turn towards the mountains in the first place. Thus, it is

reasonable to assume that EGPWS could probably have prevented all nine

(100%) of these accidents.

VNTSC Conclusion: GPWS vs. EGPWS

The VNTSC part 121/135 study credits GPWS as a significant factor

in reducing the frequency of CFIT accidents since 1975. However, these

accidents have not been totally eliminated for two major reasons:

First, many of the GPWS systems currently in use are earlier

generation systems, installed after the first GPWS rulemaking in the

1970's. Since that time, GPWS equipment has been improved. These

advances typically involve improvements in terrain detection logic that

enables increased terrain warning durations in the order of 10-15

seconds on average resulting in additional time for the pilot that can

be crucial in preventing accidents. The NTSB addressed this issue by

recommending to the FAA that early generation GPWS equipment be

upgraded. (NTSB recommendations A-92-39 through A-92-42.)

As a result, in 1996, the FAA revised TSO-C92b and issued TSO-C92c.

Specifically, this new TSO added new requirements and features to GPWS:

aural warnings that would identify the reason for GPWS warnings; the

inclusion of airspeed in the logic that determines GPWS warning times;

altitude callouts during nonprecision approaches; and warnings based on

airport location and aircraft position data.

Second, even with these added features, GPWS equipment has two

important limitations: (1) GPWS does not have the capability to ``look

forward,'' but instead only ``looks down,'' relying on radio altimeter

data. For this reason, there is little or no warning if the terrain

ahead of an airplane rises in a steep gradient. This limitation is

known as the ``vertical cliff'' limitation. (2) To prevent nuisance

ground proximity warnings during final approach, for an aircraft in

stabilized descent on a non-precision approach (i.e., one in which

lateral, but not vertical or glide slope, guidance is provided), with

gear and flaps extended, all GPWS warning modes are desensitized. Thus

a flight crew will receive no warning if their aircraft is not in fact

lined up with a runway. This limitation is known as the ``non-precision

approach (NPA) trap'' limitation.

In its conclusion, the VNTSC states that there is compelling

evidence of the potential effectiveness of EGPWS in preventing CFIT

accidents. EGPWS would have provided the same or increased warning

durations over GPWS had each aircraft continued along the accident

track, and should have provided sufficient warning to effectively

prevent all nine cases studied. The study emphasized that the CFIT

accident prevention in all cases would have resulted not so much from

increased warning durations following system detection of terrain

threats, as from the fact that flight crews, given a continuous terrain

display, would have perceived these terrain threats and responded to

them well before EGPWS was required to generate warnings.

Elaborating further, the study states that the continuous terrain

display feature of EGPWS may be even more important than the terrain

threat detection/alert/warning features in breaking the chain of

decisions leading to CFIT. Flight crews lacking visual perspective are

given a continuous display of nearby terrain, greatly heightening

situational awareness. Rather than a ``last ditch'' warning of imminent

danger, the continuous terrain display would allow crews to maneuver to

avoid terrain long before it ever becomes an obstruction to their

flight path. It thus represents a pivotal advance in providing flight

crew terrain awareness.

The FAA agrees that the terrain situation awareness display is a

valuable function and therefore proposes to mandate its use. However,

the alerting functions also are critical. Because of the various

piloting duties, functions and activities, a pilot does not monitor one

instrument 100% of the time, and this will be the case with a terrain

situation awareness display. The alerting functions provide the final

safety margin that directs the pilot to take life-saving action.

While recognizing the terrain awareness benefits of the terrain

display, the VNTSC study also recognizes that such a display may

present a new set of challenges to pilots. The TAWS's topographical map

display will offer a temptation for pilots to use it for navigational

purposes. Pilot training should emphasize that other aircraft systems

are intended for this purpose, and any TAWS terrain display features

are intended only to provide terrain awareness, not for aerial

navigation. See also Notice N8110.64, Enhanced Ground Proximity Warning

System, which provides guidance on EGPWS and specifies that Airplane

Flight Manuals should state that EGPWS shouldn't be used for

navigational purposes.

In light of the potential savings of human life and the economic

costs of destroyed or damaged aircraft, the report recommends that the

FAA amend 14 CFR parts 121 and 135 to require mandatory installation in

affected aircraft fleets of TAWS. A more detailed discussion and

analysis is included in FAA study DOT-TSC-FA6D1-96-03, Investigation of

Controlled Flight Into Terrain (For Selected Aircraft Accidents

Involving Aircraft Flying Under FAR Parts 121 and 135 Flight Rules and

the Potential for Their Prevention by Enhanced Ground Proximity Warning

System (EGPWS)).

Functions and Approval of TAWS

Functions of TAWS

Recent technological advancements--such as more precise navigation

systems, increased computer memory storage and better display

technology--have allowed the development of terrain alerting and

warning systems. Current systems under development have three common

features: (1) Use of airplane position information from the airplane's

navigation system(s), (2) an onboard terrain data base, and (3) a means

of displaying the surrounding terrain. All systems currently under

development function in the following same manner. Airplane position

information from the airplane navigation system is fed to the TAWS

computer. The TAWS computer compares the airplane's current position

and flight path with the terrain data base also in the TAWS computer.

If there is a potential threat of collision with terrain, the TAWS

computer sends warning alerts to the airplane's audio system. The TAWS

computer also inputs display data to either the weather radar, the

Electronic Flight Information System (EFIS) or some other display

screen on which then is shown the surrounding terrain with the threat

terrain highlighted. Specific certification requirements for the TAWS

is contained in TSO-C151.

An example of a specific TAWS currently certificated by the FAA

handles the above functions as follows:

(1) Alerting Times

The function of the new proposed TAWS standard is to prevent CFIT

by providing alerting times earlier than those provided by existing

ground proximity warning systems manufactured in accordance with

Technical Standard Order (TSO)-C92c. Typically GPWS aural and visual

warnings occur about 20 seconds or less before potential impact with

terrain.

[[Page 45631]]

The visual warning is usually a blinking light and the aural warning is

usually a message through the airplane's audio system.

Studies indicate that average combined pilot and aircraft reaction

time to avoid a CFIT after warning is within the 12 to 15 second range.

The FAA has approved for installation a TAWS (the EGPWS) that provides

an initial alert approximately 60 seconds before potential impact and

another alert about 30 seconds before potential impact. These alerts

are both aural and visual. These alerting times were based on data from

actual CFIT accidents and were chosen by the manufacturer as the best

compromise to provide timely alerts while still minimizing nuisance

alarms. Human factors research and FAA experience show that, if an

aural cockpit alarm sounds too often as a false alarm, the flight crew

will either begin to ignore it or will be tempted to disable the

system. Therefore, while the forward looking capability of TAWS could

provide an alert far in advance of potential impact, the alerting time

must be as short as possible, while still allowing an adequate time to

avoid impact. The FAA will carefully evaluate the alerting times for

each proposed TAWS, but expects that manufacturers will provide at

least 20 seconds in advance of a potential impact.

(2) Forward Looking Capability

The increased alerting function is made possible by a ``forward

looking'' feature. This function in turn is made possible by inputting

aircraft position from the global positioning system (GPS) or a flight

management system (FMS) into the TAWS computer in which a terrain

database is already stored. Using aircraft position, performance and

configuration data, the TAWS computer calculates an envelope along the

projected flight path of the aircraft and compares that to the terrain

database. If there is a potential impact with terrain, the system

provides appropriate aural and visual alerts. This feature also makes

possible a terrain (situational) awareness display that could be used

on a dedicated TAWS display screen, a weather radar, or an EFIS display

screen. Terrain within certain vertical distances of the aircraft is

displayed in various color densities. The FAA would accept green,

yellow and red because these are the colors currently available on the

weather radar display.

(3) Terrain Clearance Floor

TAWS also provides a terrain clearance floor that adds an

additional element of protection to the GPWS warning modes. The terrain

clearance floor creates an increasing terrain clearance envelope around

the intended airport runway directly related to the distance from the

runway. The terrain clearance floor alerts are based on aircraft

location, nearest runway center point position, and radio altitude. The

terrain clearance floor provides an alert based on insufficient terrain

clearance even when in landing configuration. This is an improvement

over the current GPWS, which becomes deactivated when an airplane's

wing flaps and landing gear are in landing configuration.

If an airport has glide-slope equipment that is operating, the

flight crew can rely on that equipment to guide the airplane; the TAWS

terrain clearance floor function may not be needed. However, if the

airport does not have glide-slope equipment or it is not operating, the

flight crew must perform a non-precision approach. In this case, if the

flight crew is unaware of its location and comes in too low or too

soon, the terrain clearance floor function would generate an aural

alarm.

Approval of TAWS

Currently, the FAA approves the manufacture and installation of

Ground Proximity Warning Systems through Technical Standard Orders.

Sections 121.360 and 135.153 require the use of GPWS meeting TSO-C92,

which has been reissued as TSO-C92a, TSO-C92b, and TSO-C92c. The FAA

does not intend to revise TSO-C92c to include TAWS requirements.

Instead, the FAA is developing and will issue a new and separate

TSO for TAWS. The new TSO-C151, Terrain Awareness and Warning System,

is being developed through the FAA TSO process which allows for public

comments. Any person desiring to review and comment on the draft TSO-

C151 may obtain a copy of the draft TSO-C151 from the person mentioned

in the section entitled FOR FURTHER INFORMATION CONTACT. This TSO would

be the means to obtain FAA approval of the TAWS product. The FAA also

will develop and issue a TAWS advisory circular (AC). This AC would

describe an acceptable means of obtaining FAA installation approval.

Notice 8110.64, Enhanced Ground Proximity Warning System (EGPWS) is the

current interim guidance to be used for the installation and approval

of TAWS. The FAA has issued a policy statement that states that the

contents of Notice 8110.64 shall remain valid until the TSO and AC are

published.

An applicant that meets the proposed requirements of TSO-C151 also

will be entitled to a TSO-C92c authorization, if requested, with a TSO-

C151 authorization. The performance and environmental standards of TSO-

C92c are included within TSO-C151. Any equipment bearing a TSO-C151

label will meet the requirements of FAR part 121.360 and 135.153.

The Proposal

The FAA is proposing to add Secs. 91.223, 121.354, and 135.154 to

require the installation of FAA-approved terrain awareness and warning

systems (TAWS). The FAA is also proposing to amend Secs. 121.360 and

135.153 to add an expiration date of four years after the effective

date of the final rule for the use of current GPWS systems, thereafter,

compliance with those sections would not be allowed in lieu of the

provisions proposed herein.

For operations under part 121 the proposed rule would apply to all

turbine-powered airplanes. For all other operations (parts 91, 125,

129, and 135) the proposed rule would apply to all turbine-powered

airplanes type certificated to have six or more passenger seats,

excluding any pilot seat. The FAA proposes that, beginning one year

after the effective date of the final rule, U.S.-registered airplanes

manufactured after that date be equipped with TAWS. The FAA also

proposes that existing turbine-powered airplanes be equipped with TAWS

within four years after the effective date of the final rule. This

requirement for existing airplanes would apply to all airplanes

manufactured on or before one year after the effective date of the

final rule. (For more discussion of the compliance dates and how they

were chosen, see the Regulatory Evaluation Summary later in this

preamble.)

The proposal would therefore ensure that all applicable airplanes

operated under parts 91, 121, and 135 have the most up-to-date and

effective equipment needed to help prevent CFIT accidents. The proposal

would also ensure that operators under part 125 and operators of U.S.-

registered airplanes under part 129, who must also comply with part 91,

are similarly equipped in order to prevent CFIT accidents.

The FAA is also proposing that operators include in their Airplane

Flight Manuals the appropriate procedures for operating and responding

to the audio and visual warnings of TAWS.

The FAA is not proposing changes to current training requirements

in this NPRM. However recent new training requirements on crew resource

management (CRM) for flight crewmembers should provide additional

[[Page 45632]]

safeguards in conjunction with the use of TAWS. This requirement will

apply to flight crewmembers operating under parts 121 and 135 and will

take effect on March 19, 1998. (60 FR 65940, December 20, 1995).

The proposed rule would apply only to turbine-powered airplanes.

The FAA specifically requests comments on whether it should require the

installation of TAWS on reciprocating engine-powered airplanes. What

would be the impact on safety of such a requirement? Are there

technical reasons why TAWS is or is not appropriate for reciprocating

engine-powered airplanes? Should TAWS be required for reciprocating

engine-powered airplanes of a certain size? The FAA will study data and

information submitted by commenters in response to these questions

before making a determination as to whether TAWS should be required for

reciprocating engine-powered airplanes. If the decision is made to

require TAWS on reciprocating engine-powered airplanes it will be

addressed in a separate rulemaking.

Impact of the Proposed Rule

The impact of the proposed rule on operations under parts 91, 121,

and 135 would be similar to the impact of the installation of TAWS on

newly manufactured airplanes, i.e., installation would be required

beginning one year after the effective date of the final rule. Because

operators under part 125 and operators of U.S.-registered airplanes

under part 129 must comply with part 91, they would also have to meet

this requirement.

The requirement for TAWS on existing airplanes would impact

operators under the affected parts differently. Those operators under

part 91 (including operators under part 125 and operators of U.S.-

registered airplanes under part 129) who are currently not required to

have GPWS would, in most cases, be required to install TAWS within the

four year compliance period. In those cases where GPWS was previously

installed on a voluntary basis, operators would also be required to

retrofit their airplanes with TAWS within four years. Retrofits would

also apply in cases where part 125 operators lease part 121 airplanes

that are already equipped with GPWS.

For existing airplanes under parts 121 and 135, which currently

must have GPWS, operators would be required to retrofit their airplanes

to install TAWS within four years. It should also be noted that the

proposed rule adds to the existing part 135 requirement by requiring

TAWS on an additional group of airplanes: those type certificated to

have six to nine passenger seats, excluding any pilot seat. The current

rule requires GPWS for airplanes with 10 or more seats under part 135.

If the operators of this group of airplanes have not already installed

EGPWS voluntarily, the proposed rule would require a new installation

of TAWS. The FAA acknowledges that this proposal may require the

retrofit of aircraft that are equipped with current generation GPWS.

For example, the 1992 rule discussed earlier, required GPWS on all

turbine-powered airplanes with 10 or more passenger seats. The FAA

specifically requests comment on the requirement for TAWS for such

airplanes. (e.g. Should the retrofit be required only in airplanes

carrying more than a certain number of passengers?)

Regulatory Evaluation Summary

Proposed changes to Federal regulations must undergo several

analyses. First Executive Order 12866 directs that each Federal agency

shall propose or adopt a regulation only upon a reasoned determination

that the benefits of the intended regulation justify its costs. Second,

the Regulatory Flexibility Act of 1980 requires agencies to analyze the

economic effect of regulatory changes on small entities. Third, the

Office of Management and Budget directs agencies to assess the effects

of regulatory changes on international trade. Finally, the Unfunded

Mandates Reform Act of 1995 requires that agencies assess the impact of

regulatory changes on State, local tribal governments and private

sector. In conducting these analyses, the FAA has determined that this

rule: (1) Would generate benefits that justify its costs and is a

``significant regulatory action'' as defined in the Executive Order;

(2) is significant as defined in DOT's Regulatory Policies and

Procedures; (3) would have a significant impact on a substantial number

of small entities, (4) would not constitute a barrier to international

trade, and (5) would not impose a significant intergovernmental mandate

on State, local or tribal governments.

Costs and Benefits for Airplanes Operated Under 14 CFR Part 121

Under the assumption that in-service airplanes must be equipped

with a terrain awareness and warning system by January 1, 2003 (four

years after an assumed effective date of December 31, 1998), the FAA

estimates that approximately 6,000 in-service airplanes operating under

14 CFR part 121 would be affected by the proposed rule. In addition,

the proposal would impact approximately 400 newly manufactured turbojet

and turboprop transports delivered to part 121 air carriers per year.

These estimates--which are based on Aircraft Registry records,

insurance data, and proprietary forecasts--do not account for voluntary

installations of TAWS equipment. Overall, the FAA projects that

approximately 1,100 airplanes operating under 14 CFR part 121 would be

equipped with TAWS by the year 2002 in the absence of any requirement.

Adjusting these estimates to account for voluntary installations,

however, would not significantly affect the conclusions since the

effect would be roughly proportional on both total benefits and costs.

The FAA approves TAWS installations either through Supplemental

Type Certificates issued to an applicant other than the airframe

manufacturer; or, in the case of the manufacturer, either a STC or a

FAA-approved type-design change. Discussions with industry indicate

that a typical first-of-type certification program would cost

approximately $79,000 for a part 121 turbojet airplane model and

$37,000 for a part 121 turboprop airplane model. These costs include

FAA engineering and administrative costs. First-of-type STC's would

then be amended to cover additional model-variants. The FAA estimates

that such amendments, also called ``follow-ons,'' could be developed at

a cost of approximately $67,000 for turbojets and $26,000 for

turboprops (again, inclusive of FAA costs).

Accurately estimating the number of STC's required by the proposed

rule is problematic since flight deck equipment may differ between

operators of the same model-variant. For example, several different

approvals may be required for different, say, B737-400's depending on

the equipment options selected by the various operators. This analysis

assumes 68 first-of-type certification programs and 84 follow-on

programs. It should be noted that, even when multiple firms perform

retrofits on a particular model-variant, the FAA would not necessarily

require multiple certification or follow-on programs: in practice, only

the first entity would incur full STC development costs. Subsequent

firms could then purchase the STC incurring incremental expenses

associated with ground and flight testing.

The FAA estimates that total STC costs (including follow-ons) for

14 CFR part 121 operators would be approximately $8.4 million, or $7.1

million at present value (assuming that STC expenses are uniformly

distributed

[[Page 45633]]

during the period 1999-2000, and that the discount rate is 7%).

Since ground proximity warning systems are already required for

part 121 operators, equipment and installation costs associated with

this proposal would include: (1) For newly manufactured airplanes, the

difference in cost between current generation GPWS and TAWS, and, (2)

for in-service airplanes, the cost of removing the existing ground

proximity warning system and replacing it with TAWS (net the rebate

value of the GPWS equipment). Since GPWS and TAWS units are

approximately the same weight, and since TAWS requires no more

maintenance than GPWS, incremental part 121 operating and maintenance

costs associated with the proposed rule are negligible.

Retrofit costs depend on the type of equipment already in use in an

affected airplane. Differences in costs can be ascribed to the relative

trade-in values of various vintages of GPWS units and the fact that, in

some cases, GPWS includes an integral windshear detection system. (In

some cases, operators may be forced to replace both the GPWS and

windshear detection systems. The analysis accounts for this additional

cost where applicable.) Unit (i.e. per airplane) retrofit costs can be

summarized as follows: (1) In-service turbojet airplanes equipped with

early-generation GPWS--$59,480, (2) in-service turbojet airplanes

equipped with current-generation GPWS--$64,980, (3) newly manufactured

turbojet airplanes--$12,000, (4) in-service 30+ passenger turboprop

airplanes equipped with early-generation GPWS--$59,480, (5) in-service

30+ passenger turboprop airplanes equipped with current-generation

GPWS--$57,280, (6) newly manufactured 30+ passenger turboprop

airplanes--$12,000, (7) in-service less-than-30-seat turboprop

airplanes--$20,600, (8) newly manufactured less-than-30-seat turboprop

airplanes--$2,000.

These unit costs include: TAWS system costs, installation kit

costs, installation labor costs, an adjustment for spares and simulator

installations (assumed to be 10% of TAWS systems costs), and

adjustments for additional navigation equipment and displays required

in some aircraft. Aside from the provision for simulator units,

incremental training costs are assumed to be negligible. The FAA

invites comment on these cost assumptions.

The FAA estimates that TAWS equipment and installation costs for

the affected in-service 14 CFR part 121 fleet would be approximately

$361.5 million, or $297.0 million at present value. Total equipment and

installation costs for newly manufactured airplanes delivered to part

121 air carriers during the ten year forecast period 1999-2008 would be

approximately $47.5 million, or $31.3 million at present value.

Therefore, total part 121 costs--including certification costs,

retrofit costs, and incremental TAWS costs for newly manufactured

airplanes delivered between 1999 and 2008--would be approximately

$408.9 million, or $328.3 million at present value.

The benefits of TAWS again depend on the type of GPWS unit it would

replace. The risk reduction potential of TAWS when measured against an

early-generation GPWS system, for example, is higher than the risk

reduction potential measured against a current-generation system. Risk

reduction estimates for various combinations of airplane types and GPWS

vintages are based on analyses of eight CFIT accidents involving 14 CFR

part 121 air carriers (this includes two part 135 air carriers now

required to operate under 14 CFR part 121) which occurred during the

ten-year period 1986-1995. The analyses--conducted by the Volpe

National Transportation Systems Center and referred to earlier in the

preamble--took into consideration, among other things, the type of GPWS

equipment (if any), on-board at the time of the accident, and the

relative effects of current-generation GPWS versus TAWS. On the basis

of the Volpe results, the FAA estimates the following rates of CFIT

risk reduction: (1) Turbojet airplanes equipped with early-generation

GPWS--0.079 averted accidents per million flight hours, (2) turbojet

airplanes equipped with current-generation GPWS--0.048 averted

accidents per million flight hours, (3) 30+ passenger turboprop

airplanes equipped with early-generation GPWS--0.079 averted accidents

per million flight hours, (4) 30+ passenger turboprop airplanes

equipped with current-generation GPWS--0.048 averted accidents per

million flight hours, (5) less-than-30-seat turboprop airplanes--0.118

averted accidents per million flight hours.

Estimates of lifecycle benefits were calculated on a per-airplane

basis and summed over all affected part 121 airplanes to obtain an

estimate of the expected fleet benefits. The calculations took into

consideration: (1) The passenger capacity of each airplane, (2) average

load factors for various types of operations, (3) the number of flight

crew, (4) the probability of fatalities given a CFIT accident, (5) the

expected value of the airplane at the time of accident, and (6) the

expected remaining service life of the airplane.

The FAA estimates that total lifecycle benefits for the affected 14

CFR part 121 fleet (including the lifecycle benefits accruing to newly

manufactured airplanes delivered during the period 1999-2008) are

approximately $5.9 billion, or $2.1 billion at present value.

Therefore, the ratio of discounted benefits to discounted costs is

approximately 6.5 to 1.0.

Three of the eight preventable part 121 CFIT accidents occurred

during international operations of U. S. carriers. The FAA evaluated

the benefits and costs of lesser requirements on operators conducting

only domestic flights. This analysis, however, showed substantial

benefits associated with the TAWS requirement for in-service airplanes

flying only domestic routes. (See the Preliminary Regulatory

Evaluation, Section VII ``Analysis of Alternatives.'')

Costs and Benefits for Airplanes Operated Under 14 CFR Part 135

The FAA estimates that approximately 1,100 in-service airplanes

operating under 14 CFR part 135 would be affected by the proposed rule.

Approximately 800 of these are 10-30 seat airplanes that are currently

required to have GWPS, and 300 are 6-9 seat turbojets and turboprops

currently not required to have GPWS. In addition, the rule would affect

approximately 500 new turbojet and turboprop airplanes delivered to

part 135 air carriers during the period 1999-2008. The FAA is not aware

of any large scale efforts to voluntarily equip part 135 airplanes with

terrain awareness and warning systems.

The FAA estimates that total certification costs for typical 14 CFR

part 135 turbojet and turboprop airplane models would be approximately

$28,000 and $20,000, respectively. An estimate of total part 135

certification costs, then, is obtained by multiplying the per-

certification costs by an estimate of the total number of

certifications required. As in the analysis of part 121, predicting the

number of required STC's for part 135 is problematic owing to potential

differences between and within airplane model-variants. In some cases,

more than one TAWS STC may be required per model, in other cases, one

STC may cover more than one model. The FAA estimates that approximately

50 turbojet STC's and 32 turboprop STC's would be required to retrofit

the affected part 135 fleet. Therefore, total fleet certification costs

are approximately $2.1 million, or $1.8 million at present value

(again,

[[Page 45634]]

assuming that certification costs are uniformly distributed during the

period 1999-2000 and that the discount rate is 7%).

As noted earlier, the incremental costs (and benefits) of the rule

depend in part on the type of GPWS equipment already in service.

Operators who already have GPWS equipment, for example, would incur no

additional operating or maintenance costs. In the absence of detailed

information on which particular airplanes have or do not have GPWS, the

FAA assumes that all airplanes are in compliance with current Federal

Aviation Regulations--but do not exceed those requirements (that is,

there is no adjustment made for voluntary GPWS installations). Thus, it

is assumed that all 6-9 passenger seat turbine engine airplanes are not

equipped with any type of ground proximity warning system.

Unit equipment and installation costs for affected part 135

airplanes are as follows: (1) In-service turbojet airplanes seating 6-9

passengers--$27,950, (2) newly-manufactured turbojet airplane seating

6-9 passengers--$26,475, (3) in-service turbojet airplanes seating 10

or more passengers--$24,300, (4) newly manufactured turbojet airplanes

seating 10 or more passengers--$7,000, (5) in-service turboprop

airplanes seating 6-9 passengers--$30,150, (6) newly-manufactured

turboprop airplanes seating 6-9 passengers--$28,575, (7) in-service

turboprop airplanes seating 10 or more passengers--$24,300, (8) newly

manufactured turboprop airplanes seating 10 or more passengers--$7,000.

(Recall that GPWS is already required for 10-30 seat airplanes.

Therefore, incremental TAWS cost for newly manufactured airplanes in

this group equal the difference in cost between TAWS and basic GPWS.)

As before, these costs include: TAWS equipment costs, installation kit

costs, GPS and display costs, and an adjustment for a radar altimeter

(not present on some aircraft).

As noted above, incremental operating and maintenance costs are

only associated with airplanes lacking GPWS equipment--by assumption

airplanes seating 6-9 passengers. The FAA estimates that the weight of

an average TAWS installation would be approximately 9 pounds for a

turbojet airplane and 8 pounds for a turboprop airplane. Annual

maintenance costs are approximately 5% of TAWS equipment costs,

therefore annual incremental operating (fuel consumption) and

maintenance costs equal $870 and $936 for 6-9 passenger turbojet and

turboprop airplanes, respectively.

Total lifecycle costs for the affected 14 CFR part 135 fleet--

including certification, equipment, installation, operating and

maintenance costs--would be approximately $45.2 million, or $30.8

million at present value. Again, this total includes projected

lifecycle costs for newly manufactured 6+ seat turbojet and turboprop

airplanes delivered to part 135 operators between 1999 and 2008.

Following the procedure discussed under part 121, the estimated

benefits for 14 CFR part 135 operations are a function of airplane

seating capacity, load factors, annual flight hours, GPWS equipage,

etc. Again, expected TAWS benefits for any particular airplane depend

on whether or not the airplane already has GPWS and, if it does, the

vintage of system installed. Risk reduction estimates are as follows:

(1) Turbojet airplanes seating 6-9 passengers--0.861 accidents averted

per million flight hours, (2) turbojet airplanes seating 10 or more

passengers--0.036 accidents averted per million flight hours, (3)

turboprop airplanes seating 6-9 passengers--2.310 accidents averted per

million flight hours, (4) turboprop airplanes seating 10 or more

passengers--0.091 accidents averted per million flight hours. For

airplanes with 6-9 seats, risk estimates are based on analyses of

approximately 40 accidents involving turbojet and turboprop airplanes

operating under 14 CFR part 91. For airplanes with 10-30 seats, risk

estimates are based on the service experience of similar airplanes

operated under 14 CFR part 121. (At the time of this writing, the FAA

has asked the Volpe center to review the part 135 CFIT accident data

from the original study

Based on these results, the FAA projects that TAWS benefits--that

is the value of reduced CFIT risks--for 14 CFR part 135 operators would

be approximately $84.4 million, or $38.2 million at present value

(including benefits accruing to affected part 135 airplanes delivered

between 1999 and 2008). Therefore, the ratio of discounted benefits to

discounted costs would be approximately 1.24 to 1.0.

The FAA notes that in the case of airplanes carrying fewer numbers

of passengers, there is a clear overall net benefit in requiring TAWS

to replace early generation GPWS. While relative benefits are lower for

smaller aircraft that have only recently been retrofitted with current

generation GPWS, excepting such airplanes could create a situation

where the FAA would require more sophisticated equipment for

noncommercial aircraft as compared with some commercial aircraft.

Costs and Benefits for Airplanes Operated Under 14 CFR Part 91

Affected 14 CFR part 91 airplanes, for the purpose of this

analysis, are defined as a residual--i.e. the total affected fleet of

U.S. registered turbine powered airplanes minus the affected 14 CFR

parts 121 and 135 fleets. The part 91 residual includes general

aviation aircraft (corporate, business, personal, instruction, aerial

application, and other), large airplanes (having a seating capacity of

20 or more or a maximum payload capacity of 6,000 pounds or more)

operating under 14 CFR part 125, and U.S. registered airplanes

operating under 14 CFR part 129. Under this simple residual approach,

the FAA estimates that approximately 5,500 turbojet airplanes and 5,700

turboprop airplanes (not operating under 14 CFR parts 121 and 135)

would be affected by the proposed rule. The FAA estimates that an

additional 220 newly manufactured turboprops and 120 newly manufactured

turbojets would be affected annually.

The FAA estimates that the proposed rule would require

approximately 57 STC's at a total cost of $1.3 million, or $1.1 million

at present value (assuming that certification costs are uniformly

distributed over the period 1999-2000, and that the discount rate is

7%).

Per airplane equipment and installation costs would be

approximately $27,950 and $30,150 for typical in-service turbojet and

turboprop airplanes, respectively. TAWS equipment and installation

costs for newly manufactured airplanes--approximately $26,475 per

turbojet airplane and $28,575 per turboprop airplane--are slightly

lower reflecting lower installation costs.

Annual incremental operating and maintenance costs would be

approximately $870 for turboprop airplanes and $936 for turbojet

airplanes. Total lifecycle costs for the affected (residual) 14 CFR

part 91 fleet, then, are approximately $642.9 million, or $415.3

million at present value. As in the analyses of 14 CFR parts 121 and

135, cost estimates include lifecycle costs for in-service airplanes

and newly manufactured airplanes delivered between 1999 and 2008.

Estimates of the benefits accruing to part 91 operators are based

on the Volpe accident analyses (discussed above). Of the 44 accidents,

11 involved turbojets and 33 involved turboprops. Probable cause, as

determined by NTSB, was pilot error in all cases--principally through

failure to maintain proper altitude, use of improper instrument flight

rules or visual flight rules

[[Page 45635]]

procedures, or poor planning/decision-making. Volpe analyses determined

that current technology ground proximity warning systems could have

prevented 33 of the 44 accidents. On the other hand, TAWS could have

prevented 42 of the 44 accidents; 11 turbojet airplane accidents and 31

turboprop airplane accidents. On the basis of the accident history, the

FAA estimates that TAWS would prevent 2.46 turboprop airplane accidents

per million flight hours and 0.86 turbojet airplane accidents per

million flight hours. This translates to fleet benefits of

approximately $1.5 billion, or $663 million at present value.

Therefore, the ratio of discounted benefits to discounted costs is

approximately 1.6 to 1.0.

The FAA invites comment on these estimates. Comments should include

details such as: (1) Alternative cost assumptions, (2) alternative

aircraft population forecasts, (3) the extent of voluntary industry

action, etc.

Analysis of Alternatives

The FAA concludes that this NPRM is a significant regulatory action

based on the proposal's expected cost, its potential impact on safety,

and the extent of public interest in this issue. For matters determined

to be significant, Executive Order 12866 requires ``an assessment,

including the underlying analysis, of costs and benefits of potentially

effective and reasonably feasible alternatives to the planned

regulation.'' Accordingly, the FAA has considered regulatory options to

identify the least intrusive and most cost-effective means of achieving

the goal of reducing the probability of CFIT accidents.

The alternatives considered fall under two general groupings: (1)

require different levels of TAWS or GPWS technologies for different

subsegments of the regulated population, and (2) impose different

compliance deadlines on different subsegments of the regulated

population.

Different Levels of TAWS or GPWS for Different Subsegments of the

Regulated Population

One group of alternatives consists of options that would require

different levels of TAWS or GPWS technologies for different subsegments

of the regulated population (including the option of not requiring GPWS

or TAWS equipment at all). There are three broad classifications of

TAWS/GPWS technologies: (1) Early-generation GPWS, (2) current-

generation or upgraded GPWS (with improved capabilities and a lower

probability for nuisance warnings), and (3) TAWS. It is possible to

identify several regulatory alternatives, then, based on these

technology levels.

One alternative would be to exclude certain types of airplanes or

operators from a TAWS or GPWS requirement altogether. Based on its

evaluation of benefits and costs, the FAA does not consider this to be

the best option. Excluding operators of 6-9 seat airplanes, for

example, would run contrary to a significant body of analyses--by the

DOT, FAA and NTSB--that indicates that a TAWS requirement would result

in substantial reductions in CFIT casualties and property losses.

Another alternative would be to require GPWS without regard to

technology. Under this option, any vintage of GPWS--even the oldest

systems--would be compliant. Approximately 95% of the world's

commercial airline fleet are equipped with some form of ground

proximity warning system. Also, anecdotal evidence suggests that there

are some other, non-air carrier operators who have voluntarily

installed GPWS. This alternative, therefore, would primarily affect

general aviation operators and commercial operators of 6-9 seat turbine

powered airplanes. There are two drawbacks to this option. First, a

detailed analysis shows that the greatest potential for CFIT fatality

reductions is produced by requiring TAWS in commercial airplanes that

are already equipped with GPWS. For 14 CFR part 121, for example, TAWS

is expected to reduce the accident rate by up to 0.079 per million

flight hours. The FAA's analysis of part 135 carriers--most of whom

already have current generation GPWS technology--also shows that

significant benefits, which more than justify the costs, can be

realized by requiring TAWS retrofit. Second, this option would

effectively force on-demand air taxi and other general aviation

operators to a higher standard than that required for the largest

commercial carriers. This follows since early generation GPWS systems

are no longer being produced for installation in the United States.

This option would therefore require small operators to install upgraded

GPWS or TAWS while many part 121 operators could legally continue to

use technology developed over 20 years ago.

A third alternative would be to require current technology GPWS

only. This alternative would also reduce the number of affected

airplanes. The FAA estimates that approximately 3,200 airplanes

operating under 14 CFR part 121, and 1,100 airplanes operating under 14

CFR part 135 already have upgraded GPWS equipment (or will have such

equipment by the projected effective date of the proposed rule). Under

this alternative, these airplanes would not require retrofit. In

addition, incremental costs associated with the purchase of newly

manufactured airplanes would be zero for part 121 operators and many

part 135 operators. (Again, this follows since early generation GPWS

units are no longer being produced for installation in the United

States.) Limiting the requirement to upgraded GPWS would also

marginally reduce compliance costs for some affected operators since

upgraded GPWS would be less expensive than TAWS in some cases. A

variant of this alternative would be to except smaller aircraft that

may have been required to, or have voluntarily been equipped with

current generation GPWS. The FAA concludes, however, that this

exception may result in requiring more sophisticated equipment on

certain noncommercial aircraft relative to some commercial aircraft.

There are safety and cost-effectiveness concerns with this

alternative. It clearly provides a lower level of safety than the

proposed rule; moreover, although this option is substantially cheaper

than the proposed rule, ironically its costs do not justify its

benefits for some types of operations. For example, in some cases the

limited risk reduction potential would not justify replacing early-

generation GPWS with upgraded current-generation systems. For airplanes

that currently lack any GPWS, the FAA concludes that requiring only

upgraded GPWS is a suboptimal strategy based on the relatively small

difference in cost between upgraded GPWS versus TAWS combined with the

relatively large differential in risk reduction potential between the

two systems. Finally, significant safety benefits would be foregone for

those airplanes already equipped with current-generation GPWS.

Clearly, there are dozens of combinations of the two previous

alternatives involving different subsegments of the U.S. registered

fleet. In general, they include: (1) Exempting, or imposing reduced

requirements on, in-service aircraft, (2) exempting, or imposing

reduced requirements on, domestic operations; (3) exempting, or

imposing reduced requirements on, non-part 121 operations; (4)

exempting, or imposing reduced requirements on, operations not

involving the carrying of passengers for compensation or hire.

The FAA does not favor options requiring TAWS installation only for

newly manufactured airplanes. While it is true that this alternative

would

[[Page 45636]]

significantly reduce compliance costs (indeed, some manufacturers are,

or will soon be, offering TAWS as standard equipment), 30 or more years

would elapse before the entire non-TAWS fleet is retired and replaced

with TAWS-equipped airplanes. The foregone benefits--reduced

fatalities, injuries, and property loss--associated with such a

strategy are serious disadvantages of this alternative.

The FAA also considered options that would combine TAWS

installations for certain newly manufactured airplanes, with a GPWS

requirement for in-service airplanes equipped with no, or early-

generation, GPWS. While less costly than the proposed rule, such

alternatives would actually be less cost-effective: significant safety

benefits associated with replacing upgraded GPWS with TAWS would be

foregone, and, as noted earlier, in many cases it does not make

economic sense to replace early-generation GPWS systems with upgraded

systems.

The accident history shows that substantial benefits can be

achieved by requiring TAWS on international flights. An obvious

alternative, then, would be to require TAWS retrofit only for airplanes

conducting international operations, and impose lesser requirements for

the remainder of the U.S. registered fleet (for example, require TAWS

on newly manufactured airplanes only). Under this strategy, operators

conducting only domestic flights would incur little or no costs. While

the FAA acknowledges that a greater-than-proportional share of CFIT

fatalities involving U.S. registered airplanes involve international

operations, analyses (see the discussion of DOT Volpe National

Transportation Systems Center analysis in the preamble, for example)

show that substantial reductions in CFIT risks can be achieved by also

requiring TAWS for domestic operations.

As part of its analysis, the FAA estimated the domestic CFIT rate

for 14 CFR part 121 carriers. This study showed that the discounted

TAWS benefits--considering the domestic CFIT accident rate alone--would

exceed discounted costs--associated with retrofitting the entire

turbine-powered part 121 fleet--by approximately 50%.

Finally, the FAA considered the option of requiring TAWS only on

aircraft carrying passengers for compensation or hire. Accident

analyses by the NTSB and DOT, however, show that a TAWS requirement

would provide substantial safety benefits--that justify TAWS costs--for

non-commercial, general aviation airplanes.

Different Compliance Deadlines for Different Subsegments of the

Regulated Population

Economic and safety considerations complicate the selection of a

meaningful compliance period. With too long a period, important safety

benefits may be foregone; with too short a period, the cost burden on

industry becomes excessive. For in-service airplanes, the compliance

alternatives can be summarized as follows: (1) Select a compliance

period shorter than 4 years, (2) select a compliance period longer than

4 years, (3) different combinations of compliance years and equipment

requirements.

Shortening the compliance period for TAWS installation, while

beneficial from the standpoint of reduced CFIT risk, would raise

important economic and technical problems. First, in the absence of

technical standards and a substantial body of TAWS installation/

retrofit experience--particularly for general aviation airplane types--

approximately 200 STC's (or STC follow-ons) or type design change

programs would have to be undertaken by industry and processed and

approved by the FAA. Substantially shortening the compliance period for

TAWS retrofit could impinge on other modification or repair work (which

may also have safety implications) and could necessitate a reallocation

of FAA resources and disrupt other FAA projects.

Second, production information provided by the manufacturer of the

only existing TAWS-compliant system indicates that building a

sufficient number of units to accommodate a shorter deadline would be

problematic. Theoretically, the FAA could grant extensions, but

widespread use of this authority would result in inefficiencies--to

modification centers, operators, and the FAA--and, in the end, result

in no sooner achieving full fleet compliance than simply selecting a

more appropriate compliance deadline in the first place.

Other costs associated with a shorter deadline include: (1)

Increased probability of service disruption, (2) decreased likelihood

of the availability of competing TAWS products, and (3) difficulties in

drafting and approving FAA technical standards for TAWS technology.

The principle objection to lengthening the compliance period is

that the flying public would forego significant safety benefits without

a substantial decrease in costs. The FAA's analysis indicates that

delaying the compliance deadline beyond the current proposal would not

result in lower downtime or certification costs. Rather, cost savings

would equal the modest return to capital (that would be spent on TAWS

equipment) that would be realized during the short time that the

operator could postpone retrofit. It is true that a longer compliance

period would permit some airplanes to be retired without retrofit.

However, these airplanes would have to be replaced with TAWS compliant

aircraft (either through purchase or lease), therefore the net cost

savings is negligible.

The FAA also considered a hybrid two-stage approach designed to:

(1) Give operators of older airplanes a cheaper compliance option, and

(2) require quicker fleet installation of at least a current generation

GPWS unit. In this approach, all U.S. registered turbine-powered

airplanes with 6 or more passenger seats would be required to have a

minimum of upgraded GPWS within an initial compliance period (e.g. 1

year); and an FAA-approved terrain awareness and warning system by a

second compliance period (e.g. 5 years). Theoretically, costs for many

operators would be lower due to lower GPWS costs and the availability

of GPWS STC's for most affected airplane models. There are two problems

with this approach

First, this proposal increases the likelihood of service

disruptions. The two-stage approach only makes sense if the initial and

secondary compliance deadlines are sufficiently far apart. If the

initial and secondary deadlines were only separated by one or two

years, for example, it is unlikely that any operator would choose to

install an upgraded GPWS system. Delaying the secondary (TAWS) deadline

is unacceptable to FAA for the safety reasons cited above. Thus, the

initial deadline--affecting all airplanes with no or early-generation

GPWS equipment--would have to be relatively early. Depending on the

specific date chosen, the initial deadline could require retrofit of

over 12,000 airplanes (with current generation GPWS) within a one or

two year period.

Second, FAA's analysis of the affected airplane population

indicates that a large number of operators of airplanes that would need

to be retrofitted by the initial deadline would choose to have TAWS

equipment (primarily because they would expect these airplanes to be

in-service after the secondary deadline). As noted above, it is

unlikely that TAWS production will be able to accommodate this demand.

Thus, operators who could not obtain TAWS would have to install

upgraded GPWS and then retrofit TAWS approximately five years later.

That is, the FAA would

[[Page 45637]]

compel some operators--most likely smaller operators with little market

influence--to retrofit twice within five years.

Third, as noted above, it is difficult to justify retrofitting

upgraded GPWS in place of an existing early-generation system. The cost

difference between GPWS and TAWS is relatively small--especially in

consideration of the trade-in value of the existing unit (in some

installations upgraded GPWS may be more expensive than TAWS)--but the

difference in risk reduction is substantial. A preliminary analysis (of

a compliance alternative that would require upgraded GPWS within one

year and TAWS within five years) showed that the projected reduction in

the part 121 CFIT accident rate associated with replacing early GPWS

with TAWS was three times the rate reduction associated with replacing

early GPWS with upgraded GPWS.

The FAA invites comment on the alternatives discussed in this

section and suggestions or other regulatory alternatives that have not

been considered. Submitted alternatives should include an analysis of

the issues discussed here, including: (1) Technical feasibility, (2)

economic considerations (e.g. TAWS production constraints, probability

of service disruption, supplier competition), and (3) public safety

impacts.

Initial Regulatory Flexibility Determination and Analysis

The Regulatory Flexibility Act of 1980 (RFA) was enacted by

Congress to ensure that small entities are not unnecessarily and

disproportionately burdened by government regulations. Specifically,

the RFA requires federal agencies to prepare an initial regulatory

flexibility analysis for any proposed rule that would have a

``significant economic impact on a substantial number of small

entities.'' The purpose of this analysis is to ensure that the agency

has considered all reasonable regulatory alternatives that would

minimize the rule's economic burdens for affected small entities, while

achieving its safety objectives.

Entities potentially affected by the proposed rule include

manufacturers of transport category airplanes, manufacturers of TAWS/

GPWS systems, and air carriers. In addition, the rule would affect many

other types of small entities which operate turbine-powered airplanes

seating six or more passengers under 14 CFR part 91 (e.g. small

business, governments, and other private or public organizations).

There are thousands of operators of such airplanes and, therefore,

potentially thousands of entities representing hundreds of industries,

organizations, and institutions. The FAA acknowledges, therefore, that

a substantial number of small entities could be significantly affected

by the proposed rule.

As noted above, the proposed rule is the culmination of an analysis

of a number of alternatives (in fact, the FAA has ruled out several

alternatives that would have imposed more costly requirements on small

entities). Three cost-reducing compliance options were considered for

small entities specifically: (1) Exclude small entities, (2) extend

compliance deadline for small entities, and (3) establish lesser

technical requirements for small entities.

The FAA's analysis indicates that the option to exempt small

entities from the requirements of the proposed rule is not justified.

In fact, as noted in the preamble, the accident history of part 91

operators (many of whom are small entities) forms the basis of the

NTSB's recommendation to require ground proximity warning systems on

smaller turbojet and turboprop airplanes.

The FAA also considered options that would lengthen the compliance

period for small operators. The requirement as proposed, however, would

place a modest burden on small entities with respect to time

constraints. Small entities--by definition operating small numbers of

airplanes--would have four years from the effective date of the rule to

complete retrofit work. As noted earlier, delaying the compliance

deadline beyond the current proposal would not result in lower downtime

or certification costs. Rather, cost savings would equal the modest

return to capital (that would be spent on TAWS equipment) that would be

realized during the short time that the operator could postpone

retrofit. On the other hand, lengthening the compliance period would

expose airplane occupants to significant safety risks for a longer

period of time.

Finally, the FAA's analysis indicates that compliance options that

would permit non-TAWS technologies are not cost-effective. For

airplanes not equipped with any ground proximity warning system, TAWS

units would provide up to 23% greater CFIT risk reduction over current-

generation GPWS at very little additional cost. (In fact, in some

installations, upgraded GPWS may be more expensive than TAWS.) In cases

where aircraft already have GPWS, VNTSC and FAA analyses indicate that

the safety benefits of TAWS outweigh the costs of retrofit.

The FAA invites comments on its analysis of small entity impacts

and alternatives. Comments should include: (1) Compliance issues that

are specific to small entities (e.g. cost and technical feasibility),

(2) public safety impacts, and (3) other small entity compliance

alternatives not considered here.

International Trade Impact Assessment

Recognizing that nominally domestic regulations often affect

international trade, the Office of Management and Budget directs

Federal Agencies to assess whether or not a rule or regulation will

affect any trade-sensitive activity. The proposed rule could

potentially affect international trade by burdening domestic businesses

or air carriers with requirements that are not applicable to their

foreign competitors. In general, the FAA concludes that the potential

international trade impacts associated with the proposed rule would be

negligible. Many domestic and foreign air carriers are already

voluntarily installing TAWS equipment in recognition of the substantial

safety benefits. A summary of potential impacts follows.

There is only one line of FAA-approved systems that meets the

requirements of the proposed rule. The proposed requirement could give

the manufacturer of this product line a competitive advantage relative

to foreign and domestic competitors by creating a substantial and

immediate demand for enhanced GPWS units. Monopolistic control of this

large market, in turn, may permit the manufacturer to take advantage of

scale economies and learning curve effects--advantages that would be

unavailable to other potential manufacturers who have not yet developed

TAWS equipment. This production cost advantage may permit the dominant

manufacturer to set prices so as to exclude market entry, but maintain

economic profits. (``Economic profits'' in the sense that they are

above the standard return for that particular industry.)

The FAA's analysis indicates that the proposed rule would have a

negligible effect on the competitive position of domestic airframe

manufacturers. Under the proposed rule, domestic manufacturers, could

continue to offer basic GPWS units on airplanes sold to foreign

customers (if the airplane is not U.S. registered). Foreign airframe

manufacturers, on the other hand, would be required to equip airplanes

sold to U.S. customers (operating under 14 CFR parts 91, 121, or 135)

with TAWS.

Domestic firms leasing aircraft to foreign operators may be

adversely

[[Page 45638]]

affected by the part 91 provisions of the proposed rule. Domestic

leasing companies, for liability reasons or to position themselves to

lease to both 14 CFR part 121 and foreign carriers, often choose to

maintain U.S. registered fleets. Thus, their lease prices would have to

reflect TAWS retrofit costs while the prices of foreign competitors

would not (in some cases, the lessee is directly responsible for

modifications required by airworthiness directive or regulations--but

in either case the disincentive effect is the same). Given the small

cost of TAWS relative to average airplane values, the FAA concludes

that the potential international trade impact would be small. Also,

TAWS equipped airplanes would be safer and thus more attractive to

potential lessees--and their passengers. Increased patronage

attributable to the operation of safer airplanes would also partially

offset the costs of compliance.

The potential impact to air carriers is, again, a function of the

aircraft registration. Foreign air carriers operating U.S. registered

airplanes would be required to install TAWS as would U.S. air carriers.

To this extent, operators of U.S. registered airplanes would have costs

not applicable to non-U.S. registered competitors.

Conversely, CFIT accidents are a leading cause of commercial

aviation fatalities worldwide. It is likely that knowledgeable

passengers would be more than willing to pay the small difference in

price to travel on an airplane equipped with TAWS. Voluntary industry

initiatives to install enhanced ground proximity warning systems are

consistent with the view that TAWS benefits far exceed its costs, and

could have beneficial effects for domestic airlines competing for

international passenger traffic.

Unfunded Mandates Reform Act Analysis

Title II of the Unfunded Mandates Reform Act of 1995 (the Act),

enacted as Pub. L. 104-4 on March 22, 1995, requires each Federal

agency, to the extent permitted by law, to prepare a written assessment

of the effects of any Federal mandate in a proposed or final agency

rule that may result in the expenditure by State, local, and tribal

governments, in the aggregate, or by the private sector, of $100

million or more (adjusted annually for inflation) in any one year.

Section 204(a) of the Act, 2 U.S.C. 1534(a), requires the Federal

agency to develop an effective process to permit timely input by

elected officers (or their designees) of State, local, and tribal

governments on a proposed ``significant intergovernmental mandate.'' A

``significant intergovernmental mandate'' under the Act is any

provision in a Federal agency regulation that will impose an

enforceable duty upon State, local, and tribal governments, in the

aggregate, or by the private sector, of $100 million (adjusted annually

for inflation) in any one year. Section 203 of the Act, 2 U.S.C. 1533,

which supplements section 204(a), provides that before establishing any

regulatory requirements that might significantly or uniquely affect

small governments, the agency shall have developed a plan that, among

other things, provides for notice to potentially affected small

governments, if any, and for a meaningful and timely opportunity to

provide input in the development of regulatory proposals.

The FAA has determined that the proposed rule would likely have an

economic impact on the private sector exceeding $100 million in certain

years; and that the economic impact to State, local, and tribal

governments would be far less than this threshold. Since the proposed

rule does not impose an enforceable duty upon State, local, and tribal

governments in the aggregate, of $100 million (adjusted annually for

inflation) in any one year, the FAA concludes that it does not

constitute a significant intergovernmental mandate as defined in the

Act.

Federalism Implications

The regulations proposed herein would not have substantial direct

effects on the States, on the relationship between the national

government and the States, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this rule

does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

Paperwork Reduction Act

As required by the Paperwork Reduction Act of 1995 (44 U.S.C.

3507(d)), the FAA has submitted a copy of these proposed sections to

the Office of Management and Budget for its review. The agency is not

collecting information. This NPRM proposes to mandate a Terrain

Awareness and Warning System for all turbine powered airplanes of 6 or

more passenger seating. TAWS is a passive, electronic, safety device

located in the avionics bay of the airplane. TAWS alerts pilots when

there is terrain in the airplanes' flight path. Since there is not an

actual collection of information, we cannot estimate a burden hour

total. However, for the purpose of controlling this submission, we will

assign a one hour burden to the package. There is a total cost estimate

of 140 million dollars per year, for installation of the passive,

electronic, safety device.

Organizations and individuals desiring to submit comments on the

information, billing, and collection requirements should direct them to

the Office of Information and Regulatory Affairs, OMB, Room 10202, New

Executive Office Building, Washington, DC 20503; Attention: Desk

Officer for Federal Aviation Administration. These comments should

reflect whether the proposed collection is necessary; whether the

agency's estimate of the burden is accurate; how the quality, utility

and clarity of the information to be collected can be enhanced; and how

the burden of the collection can be minimized. A copy of the comments

also should be submitted to the FAA Rules Docket.

OMB is required to make a decision concerning the collection of

information contained in this NPRM between 30 and 60 days after

publication in the Federal Register. Therefore, a comment to OMB is

best assured of having its full effect if OMB receives it within 30

days of publication. This does not affect the deadline for the public

to comment on the NPRM.

International Compatibility

The FAA has reviewed corresponding International Civil Aviation

Organization international standards and recommended practices and

Joint Aviation Authorities requirements. TAWS is a new system recently

developed by American industry. The FAA intends to work through the

ICAO process to harmonize this rule with the international community.

List of Subjects

14 CFR Part 91

Aircraft, Aviation safety.

14 CFR Part 121

Aircraft, Aviation safety, Safety.

14 CFR Part 135

Aircraft, Aviation safety.

The Proposed Amendment

For the reasons discussed above, the Federal Aviation

Administration proposes to amend 14 CFR parts 91, 121, and 135 as

follows:

PART 91--GENERAL OPERATING AND FLIGHT RULES

1. The authority citation for part 91 continues to read as follows:

[[Page 45639]]

Authority: 49 U.S.C. 106(g), 40103, 40113, 40120, 44101, 44111,

44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 46306,

46315, 46316, 46502, 46504, 46506-46507, 47122, 47508, 47528-47531.

2. Section 91.223 is added to read as follows:

Sec. 91.223 Terrain awareness and warning system.

(a) Airplanes manufactured after [one year after the effective date

of the final rule]. No person may operate a turbine-powered U.S.-

registered airplane type certificated to have six or more passenger

seats, excluding any pilot seat, unless that airplane is equipped with

an approved terrain awareness and warning system, including a terrain

situational awareness display, that meets the requirements of TSO-C151.

(b) Airplanes manufactured on or before [one year after the

effective date of the final rule]. No person may operate a turbine-

powered U.S.-registered airplane type certificated to have six or more

passenger seats, excluding any pilot seat, after [4 years after the

effective date of the final rule] unless that airplane is equipped with

an approved terrain awareness and warning system, including a terrain

situational awareness display, that meets the requirements of TSO-C151.

(c) Airplane Flight Manual. The Airplane Flight Manual shall

contain appropriate procedures for--

(1) The use of the terrain awareness and warning system; and

(2) Proper flight crew reaction with respect to the terrain

awareness and warning system audio and visual warnings.

PART 121--OPERATING REQUIREMENTS; DOMESTIC, FLAG, AND SUPPLEMENTAL

OPERATIONS

3. The authority citation for part 121 continues to read as

follows:

Authority: 49 U.S.C. 106(g), 40113, 40119, 44101, 44701-44702,

44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-44904,

44912, 46105.

4. Section 121.354 is added to read as follows:

Sec. 121.354 Terrain awareness and warning system.

(a) Airplanes manufactured after [one year after the effective date

of the final rule]. No person may operate a turbine-powered airplane

unless that airplane is equipped with an approved terrain awareness and

warning system, including a terrain situational awareness display, that

meets the requirements of TSO-C151.

(b) Airplanes manufactured on or before [one year after the

effective date of the final rule]. No person may operate a turbine-

powered airplane after [four years after the effective date of the

final rule], unless that airplane is equipped with an approved terrain

awareness and warning system, including a terrain situational awareness

display, that meets the requirements of TSO-C151.

(c) Airplane Flight Manual. The Airplane Flight Manual shall

contain appropriate procedures for--

(1) The use of the terrain awareness and warning system; and

(2) Proper flight crew reaction with respect to the terrain

awareness and warning system audio and visual warnings.

5. Section 121.360 is amended by adding paragraph (g) to read as

follows:

Sec. 121.360 Ground proximity warning--glide slope deviation alerting

system.

* * * * *

(g) This section expires on [four years after the effective date of

the final rule].

PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON-DEMAND OPERATIONS

6. The authority citation for part 135 continues to read as

follows:

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44709,

44711-44713, 44715-44717, 44722.

7. Section 135.153 is amended by adding paragraph (f) to read as

follows:

Sec. 135.153 Ground proximity warning system.

* * * * *

(f) This section expires on [four years after the effective date of

the final rule].

8. Section 135.154 is added to read as follows:

Sec. 135.154 Terrain awareness and warning system.

(a) Airplanes manufactured after [one year after the effective date

of the final rule]. No person may operate a turbine-powered airplane

type certificated to have six or more passenger seats, excluding any

pilot seat, unless that airplane is equipped with an approved terrain

awareness and warning system, including a terrain situational awareness

display, that meets the requirements of TSO-C151.

(b) Airplanes manufactured on or before [one year after the

effective date of the final rule]. No person may operate a turbine-

powered airplane type certificated to have six or more passenger seats,

excluding any pilot seat, after [insert date 4 years after the

effective date of the final rule], unless that airplane is equipped

with an approved terrain awareness and warning system, including a

terrain awareness and warning system, that meets the requirements of

TSO-C151.

(c) Airplane Flight Manual. The Airplane Flight Manual shall

contain appropriate procedures for--

(1) The use of the terrain awareness and warning system; and

(2) Proper flight crew reaction with respect to the terrain

awareness and warning system audio and visual warnings.

Issued in Washington, DC, on August 19, 1998.

Thomas E. McSweeny,

Director, Aircraft Certification Service.

[FR Doc. 98-22751 Filed 8-25-98; 8:45 am]

BILLING CODE 4910-13-P