It's a wonder the plane didn't crash with you using that newfangled GPS inflight. And violating AA's rules.

Cool. I'm gonna sneak mine aboard my flight this week.

Every so often, I've landed at LAX (from JFK or ORD) well ahead of schedule - half an hour to an hour early. When this happens, the pilots will usually explain that headwinds were much less than anticipated. Pilots have told me that headwinds of 50-100 knots are common when flying westbound.

Everytime I fly eastbound to LHR and see a groundspeed of 700+, it's obvious that we are flying with a very strong tailwind, since the typical cruising airspeed of the 777 is about 555. Several times, other Flyertalkers have reported displayed groundspeeds in excess of 700. Of course, don't have any idea how accurate the airshow display's numbers are. Still very impressive.