reply to post by SPreston
Suddenly the plane changes
a) the altitude (second line, first number including arrow for climbing or descending):
one moment, it is at 31200 ft., descending
the next moment, it is at 35000 ft., climbing
b) the speed (second line, second number):
one moment, it is 476 mph
the next moment, it is 458 mph
c) the estimated arrival time (fourth line):
one moment, it is 1:21 p.m.
the next moment, it is 1:16 p.m.
For non-pilots I see how this could be confusing. Ever heard of momentary glitches?? AND, the "source" is flightexplorer...
Flightexplorer is owned by Sabre...a computer system that provides the reservations and dispatching ond other operations for American Airlines.
For the data in Flightexplorer, it comes from the FAA first, then is routed to the piece you see as a layman consumer. The American Airlines
dispatchers have a better feed, directly into their building. THEY
would have seen any alleged "swap"!!
Again, this is pure speculation, from a source you found on the internet.
And, if....big IF...there was a 'swap', to you really think they'd be that amateurish about it??? They'd never make a big altitude mistake like
that...heck, they'd turn off the Mode C temporarily...so the altitude data would just drop out for a few seconds, happens all the time.
As to the Groundspeed and ETA??? Hint: Groundspeed changes, ETA changes. Headings change, ETA can change. The computers are recalculating....winds
vary....that's why it's called an Estimated
Time of Arrival! Plus, the ETA that was depicted on Flightexplorer was for the
ETAs for the next waypoint, or VOR, or other fix only minutes ahead are far more accurate. ETAs for the final destination will
fluctuate, depending on the computer doing the calculating.
For instance: We know an ETA from the computer flight plan time, added to the 'Off' time. In flight, the ETA shown on the FMC will vary, because
the computer is looking at current
winds, and groundspeed. Of course, by inputting the forecasted
wind data along the entire route of
flight, for each leg, the ETA in the FMC will be more accurate, and won't fluctuate as much.