View Single Post
Old 22nd August 2006, 12:39 PM   #2646
Join Date: Jun 2006
Posts: 2,918
Originally Posted by MikeW View Post
Glad to hear it. What do you think it clarifies, apart from that bit you've quoted? Any analysis & thoughts will be useful.
A few things stood out. One, they used basic autopilot modes coupled with VOR navigation. They did not re-program the FMC(which is a snap), instead they engaged HDG select and Vertical Speed/Altitude select. Those are the most basic autopilot modes and they are modelled in MSFS(which the hijackers were in possesion of).

However, even though the EFIS was in the MAP mode at
the time, it was in the 80 nautical mile range setting, and so would not have shown DCA on the display; consequently, it is unlikely that the hijackers used the map display on the EHSI to deduce the correct heading for Washington. It follows that the hijackers had some other means of obtaining this heading.
In the case of AA77, they actually didn't use the EHSI as a GPS of sorts, as I thought they might. Map mode can display airports(like DCA) and navaids up to 320 miles out. Instead, they changed the EHSI mode to VOR and tuned up their navaid and homed it as if they were flying a Cessna. Initially, they were out of range of the VOR. The initial intercept was was probably predetermined from practice runs in MSFS. Once the navaid was in range, they adjusted the course to line up and dialed the HDG knob to match.

Another thing that stood out was the slopiness and poor planning of the descents. UA 93 started down waaaay too early(probably why some had success using their cells). AA77 was in good shape 38 miles away at 7000'(normally in a descent an airliner at that range would still be 10-12,000' or more), but somehow still overshot and had to do that altitude bleeding turnaround. Another thing I noticed in the case of AA77 is that Hani kept getting autopilot disconnects, he ended up trying both the L and R autopilots. I think was essentially fumbling around - and it kept disconnecting because his inputs were out of bounds and it finally stayed on after he started using IAS/FLCH modes...

All in all, they seemed well rehearsed, if a little sloppy.
apathoid is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Back to Top