framer:
That is an interesting point. At some stages his ideas were considered "crazy" , ( ie getting the terrain data from Russia). If it was all happening now I imagine he would have been stone-walled at several different stages along the way. Progress?
Government fiat moved first GPWS and subsequently EGPWS. Don was always ahead of the "power curve" but the airlines wanted no part of GPWS. (pretty much the same inertia then as today.)
Then TWA 514 plowed into a speck of a hill west of Dulles on December 1, 1974. Within a short period of time then-FAA Administrator Butterfield (of Nixon fame) mandated GPWS. (Most airlines went for GPS, however.)
But, GPWS didn't save AAL 965 from plowing into the mountains north of Cali, Colombia. Some thought if could have, had the crew retracted the speed brakes. But, they didn't so they just missed clearing a ridge line. By the time of this crash (12-20-1995) GPS was operational and Don already had a working model of his EGPWS.
Having worked with Don on TWA 514 I was invited to see the beta model of the EGPWS in his unit's King Air. I was impressed. So were the regulatory movers and shakers.
Unbelievable at the time, the FAA didn't mandate GPS be used as the positioning engine for EGPWS because some airlines complained (whined) that their airplanes were IRU/DME/DME RNAV and they didn't want to shell out an additional $1,500 per old RNAV airplane. So the FAA let them use IRU/DME/DME as the positioning engine.