When I was at Stafford Uni, one of the lecturers told a story of an ex-student of his that designed the nav-systems for a fighter jet. They failed to take into account the horizon flip at the equator - as a result the planes flipped over and flew inverted every time they crossed the equator

I find that hard to believe. Sounds like the kind of story you hear after a few pints. I'd think fighter jets would depend on gravimeters to determine uprightness ...

I think this is one of those scare your students stories that all Comp Sci professors tell. I heard the same thing in one of my classes.

I remember when I was a student back in the 80s we had a guest lecturer from one of the aircraft manufacturers who related a couple of tales.

The first was that when some planes (can't remember which ones now) were pointing due north, they would fail to start up. They were apparently designed to check their electronic compasses and a little measurement noise was acceptable. When north, the noise could make the compass output flick between close to 0 and close to 360, which the computers decided was a lot of noise and shut the thing down.

The second tale was that the computers in one experimental plane would fail when high-G turns were performed. They traced the problem to certain components in the system being socketed. During the turns the forces were enough to pull those chips from their sockets.

I found a blurb in a RISKs digest:

F-16 Problems (from Usenet net.aviation)

Bill Janssen <janssen@mcc.com>

Wed, 27 Aug 86 14:31:45 CDT

A friend of mine who works for General Dynamics here in Ft. Worth wrote some of the code for the F-16, and he is always telling me about some neato-whiz-bang bug/feature they keep finding in the F-16:

o Since the F-16 is a fly-by-wire aircraft, the computer keeps the pilot from doing dumb things to himself. So if the pilot jerks hard over on the joystick, the computer will instruct the flight surfaces to make a nice and easy 4 or 5 G flip. But the plane can withstand a much higher flip than that.

So when they were 'flying' the F-16 in simulation over the equator, the computer got confused and instantly flipped the plane over, killing the pilot [in simulation]. And since it can fly forever upside down, it would do so until it ran out of fuel.