Thank you! I will have to take a closer look to these links.
So is it true then, that FDR data provided by the NTSB stated that GPS was operational?
And that the Pilots didn't calibrate the INS before start, as required for a non GPS Plane?
Is it true, that the data shows, that the flight took of from a gate different from the one officially stated?
NTSB did not say the GPS was operation, it was not installed. 77 had no GPS.
The Navigation system was initialized before takeoff, it has errors up to 2000 feet, and in the "old days" of ins only crossing of the ocean, two to six miles errors were accumulated. 77 used DME/VOR to correct the position over time.
The official gate is confirmed because ground controller said 77 taxied from a certain gate, and the navigation position has errors, so the crew does not care where the INS says they are on the ground, they can see with eyes to navigate the taxi to the runway, they don't use navigation to taxi, they have eyes.
77 did not take off from a gate, they taxied from a gate to the runway using their eyes; the official gate is where they taxied from in the real world.
An INS is not perfect, it can start with a 1/4 mile error from INS only, and INS only can drift up to 2 to 6 miles on a long mission.
Yes, the FDR navigation fixes show 77 from a different gate, and off the runway at takeoff, I think 1000 to 2000 feet to the south of the takeoff runway. It is reality of the navigation system in 77.
Pilots for truth make the claims about the navigation, thinking it is exact. They said 77 was at a different gate, and other nonsense, and ignore the evidence. Pilots for truth ignore system errors in the navigation system. An INS does not start at the exact place you tell it is at, it has to align, and during alignment errors in the system keep it from being exact.
Notes on navigation accuracy:
Lindberg used dead reckoning and made it to Paris using a compass.
Using celestial navigation with a sextant, as long as we were less than 25 miles off course when approaching land, we were okay, and fixes could be a accurate as a mile.
VOR and DME, errors of a half mile, or 3 percent of the distance from station were inside the system errors.
INS, 1/4 or less start error, 2 to 6 miles crossing the ocean.
If you are concerned about accuracy, the airways in the past were 8 miles wide... using GPS has caused accidents, because GPS is so accurate both planes going opposite directions at the wrong altitudes hit. Now there are procedures to alter flight paths left and right to avoid this kind of super accuracy accident, where being right is not a good thing when other things are wrong.
In this thread, plots of some of the 24 hours of FDR navigation points are plotted, note the errors in actual position.
http://www.internationalskeptics.com/forums/showthread.php?t=202034
Here is 77 pushing back from Dixie 26 - the spot 77 was in, for real on 911.
Confirmed by 77's pilot, and ground control who is watching from Tower, all verbal testimony, proving 77 taxied from D-26. The navigation system drifts, has errors, these are facts, reality.
