The opinion
McGOWAN, Circuit Judge,
concurring, in which BAZELON, Chief Judge, joins;
I concur in Judge MacKINNON’s thorough and perceptive opinion; and add this brief statement only to express my understanding of what has been conclusively determined by it. Because the Civil Aeronautics Board irrationally limited its diversification inquiry and resulting regulatory measures to the three petitioner airlines, it must, if it persists in this regulatory objective, initiate a new proceeding that provides for the participation by, and the consideration of, all air carriers who have achieved diversification by any means or may have an interest in doing so in the future. It is my understanding that in the new proceeding the issue of the existence, source, and scope of the Board’s authority to impose a regulatory program of the kind here involved continues to remain open.
As Judge MacKINNON’s decision makes clear, on the record before us we do not find petitioners’ arguments .that the Board exceeded its statutory authority so persuasive as to warrant our disposition of these appeals on that ground, as petitioners would have us do. Nonetheless, because the authority issue is not wholly free from doubt in at least some of its aspects, and because we must in any case vacate and remand the Board’s decision for further proceedings, it seems appropriate to allow those proceedings, enlarged as they will be by new parties who have not as yet been heard on this score, to shed additional light on the subject before we finally decide it, if we are called upon to do so.