Perhaps the largest potential order for the Tomcat (other than the Navy) was from the US Air Force. The Air Force instituted a series of studies (Advanced Manned Interceptor, CONUS Interceptor, etc.) during 1971-72 for a new interceptor and had considered a wide variety of possibilities, including a modified Lockheed YF-12A, an improved General Dynamics F-106, the McDonnell Douglas F-15 and the Grumman F-14. The YF-12 and F-106 were dropped from consideration in late-1971, and the F-14 was generally rated at par or slightly superior than the F-15 in the interceptor role. The studies later included a stretched, F100 powered F-111, designated F-111X-7, and a modified North American RA-5C powered by three J79s and designated NR-349. Initial funding consisted of $5 million in FY73 money for continued engineering studies, but the program was cancelled shortly thereafter.
In the mid-1970s the Air Force conducted another study for a Follow-On Interceptor (FOI) to replace the F-106. Although the service favored the F-15 since it was already in their operational inventory, they again had to concede that the F-14 was a better, if more expensive, aircraft for the role. As it ended up. the FOI project went through many iterations of studies to determine the best aircraft for the job, but was never funded to actually go out an buy any aircraft. The projected costs of the F-14 were $24 million per new copy, or $13 million for refurbished Iranian aircraft if they could be repurchased from Iran. The USAF F-14 looked very much like the Navy F-14 but had an enormous conformal fuel tank on the belly and could carry four external fuel tanks.
In 1977, General Daniel James, commander of NORAD, urged the Air Force to again consider the purchase of F-14s for the continental defense role. Two years later his successor, General James E. Hill did the same. It was thought that a total of 170 aircraft would be needed to replace the remaining F-106s. Although it appeared on the surface as though no modifications would be needed to the F-14, in fact they were fairly extensive.
A ground-clutter elimination mode would have to be added to the AN/AWG-9 radar system since most of the Air Force’s intercepts occur over land. The aircraft radios, IFF, and ECM equipment would have to be changed to Air Force standard equipment, or else the logistics would be a nightmare. An Air Force- style boom aerial refueling system would have to be installed in place of the Navy probe-and- drogue system. In addition, the engine installation would have to be changed slightly to accommodate a TF30 model already in the Air Force inventory for the F-111, although this was expected to be simple enough.
But much of the ground support equipment already in the Air Force inventory could have been used and the test sets built to test the F-15′s AN/APG-63 radar could be readily adapted to test most of the AN/AWG-9. Many of the Tomcat unique items could be contracted out to the Navy for maintenance, although how this would have worked in time of war is anybody’s guess. Needless to say, this latter idea did not sit well with many USAF maintenance officers.
Studies showed that in FY75 dollars, a force of 170 F-14S would cost the Air Force $4.3 billion, compared to $3.9 billion for a similar force of F-15S. Grumman argued that to adequately replace 170 F-14s, upwards to 300 F-15S would be needed, which would give a decided advantage to the F-14 in terms of cost. Again, no money was forthcoming to buy any aircraft, and the Air Force would have to wait several more years before being able to transfer some older F-15As into the continental defense role. Even later, this role would be assumed by early model F-16s.