Monday, October 28, 2013

FAA History Lesson -- October 26, 1999



From the Update to FAA Historical Chronology 1997-2012 (A .pdf file)

"A Learjet, without a pilot in control, flew for almost four hours from Orlando, Florida, to a swampy grassland in South Dakota. The Learjet was shadowed by USAF and Air National Guard jet fighters, whose pilots reported that the aircraft's windows were frosted over, suggesting that it had lost pressurization. USAF pilots also reported that the Learjet meandered from as low as 22,000 feet to as high as 51,000 feet, but never strayed from a northwest heading. Pentagon officials said the military began its pursuit of the aircraft at 10:08 a.m., when two Air Force F-16 fighters from Tyndall Air Force Base in Florida on a routine training mission were asked by FAA to intercept it. The F-16s did not reach the Learjet, but an USAF F-15 fighter from Eglin Air Force Base in Florida got within sight of the aircraft and stayed with it from 11:09 a.m. to 11:44 a.m., when the military fighter was diverted to St. Louis for fuel. Fifteen minutes later, four Air National Guard F-16s and a KC-135 tanker from Tulsa were ordered to try to catch up with the Learjet, but got only within 100 miles. Two other Air National Guard F-16s from Fargo, North Dakota, intercepted the Learjet at 12:54 p.m., reporting that the aircraft's windows were fogged with ice and that no flight control movement could be seen. At 1:14 p.m., the F-16s reported that the Learjet was beginning to spiral toward the ground. Professional golfer Payne Stewart was killed in the crash. "

I hope you'll take a few moments and let your mind wander through this scenario. Ask a few questions. "How long does a verified Mode C remain verified?" "How much vertical spacing do you give to a Lear and 2 fighters that wander around from FL220 to FL510 and then to the ground?" I'm a big fan of The Book but some things aren't in The Book.

Don Brown
October 28, 2013

1 comment:

LRod said...

I'm less concerned with the Mode-C aspects than I am with the fact that of all the military installations along or adjacent to the flight track (and easily projected once the Lear failed to make the turn at TLH) interceptors were apparently only able to maintain contact for around an hour in two separate segments. I'm not sanguine with the air defense implications of that performance.

Also, in that time of altitude fluctuation, what did the data blocks reflect? Did Mode-C function properly?

The answer to your last question is simple, in my mind. You don't use vertical at all. Basically block all altitudes.

I've made a "last assigned altitude was FL350" handoff to approach control when a Rework A4 flamed out on a test hop and lost electrical (I found out later). He got it relit (and was able to talk again) at around 15,000'. I owned FL240 and above, approach owned FL230 and below. Basically, we just kept everyone away from his primary target.

LRod
ZJX, ORD, ZAU retired