macleod@drivax.UUCP (MacLeod) (04/17/89)
From: macleod@drivax.UUCP (MacLeod) :My brother was a crew chief on F-111s at Mt Home and Tahkli (sp?) and the :biggest problem was pilots flying them into the ground. He lost three in :his enlistment. One in Vietnam was found impacted on a mountain ledge, said :it missed the top by about 100 feet. Two in Mt Home were lost on the range :but the pilots ejected, one capsules bladder never inflated and broke their :backs. All in all he liked it better than the F-4 for maintenance, said he :felt bad when the aircraft recovered and his didn't come back. My reference books tell me that the F111 has a special kind of NOE autopilot that chugs along near to the ground. It has two settings: normal and "barf bag". The BB setting hugs the ground even closer and subjects crews to 2-3G and equivalent negative G maneuvers. Given this kind of ride, it isn't surprising that some crash into obstacles. Michael Sloan MacLeod (amdahl!drivax!macleod)
ham@hpsmtc1.hp.com (Bob Hamilton) (04/21/89)
From: hplabs!ham@hpsmtc1.hp.com (Bob Hamilton) I was in the Air Force 1965 - 1972, and involved with the FB-111 weapon system for the last four of those years (simulator maintenance). The FB-111 could be navigated (in pitch) during low altitude flight by a terrain-following radar (TFR). The TFR had three clearance settings: 200 feet, 500 feet, and 1,000 feet, as I recall, and three "ride" settings: hard, medium, soft. 1,000-soft was the smoothest, 200-hard was the roughest. Normally, the autopilot was slaved to the TFR duing low altitude flight, and the plane "flew itself" (quite well, too). It was possible to change this to "manual" mode, in which the TFR issued "commands" which the pilot followed manually. At 200'-hard setting, this required considerable skill. During the time I was involved, 2 or 3 F-111's flew into the ground. In each case in which the results of the post-crash investigation were published, the TFR was found to have been in the MANUAL mode. My associates and I felt that this was a very foolish way to fly the F-111 at low altitude. --Bob Hamilton Software Methods Lab Hewlett Packard Company Cupertino, California (408) 447-5113 ham@hpda