Autoland Crash
From viewer Anders
Thorsland:
"Please
note that the video is NOT an autoland accident ... please correct ...
The flight took off from LFSB (Basle Mulhouse Freiburg airport) about 10 nm
due
south of Habsheim airport where the crash took place.
The airplane in question was part of an airshow at Habsheim and was one of
the
star attractions. The flight was briefed before departure to be flown in
"direct
law" by the pilots. This means with no alpha floor protection.
The pilots demonstrated a lack of understanding of the flight computer
architecture and laws. They thought they could not stall or have an accident
with this airplane - a la the Titanic I guess ...
Contributing factor was the fact that the crew had virtually no experience
on
"big fan engines" and the rather long spool-up times. They came from Air
Inter
and the rather unsuccessful "737 buster" made by Aerospatiale .... can't
think of
the name right now I am afraid.
You can clearly hear on the video that the engines spool up and probably had
full thrust as it sinks into the trees and catches fire."
New 4/8/06
From a United Air LInes employee: "Well, just when you
thought you heard the "real story", the REALLY REAL STORY finally comes from
a United Airlines Flight Simulator Instructor based in Denver, Colorado."
"There are bits and pieces that are correct in the first two
explanations. It's true the pilot was not satisfactorily trained in this new
kind of fly-by-wire flight control system of the time that also included the
THROTTLES! It's also true if you pull an Airbus side stick controller
back far enough without sufficient speed the flight computer takes over and
reduces the angle of attack regardless what position you continue to hold
the stick. You cannot "override" this system, contrary to public
belief."
"Same goes for the early Airbus throttles. If you are in "landing" mode,
it doesn't matter how far you advance the throttles, the flight computer is
commanding the engine power output when in a set mode."
"The pilot had commanded the aircraft to do a slow fly-by in the
"landing" configuration at a bugged airspeed. The problem came when the
pilot attempted to climb-out at the end of his fly-by. The flight computer
ignored his stick inputs because he didn't have sufficient speed or
configuration to pull-up."
"Conversely, the flight computer also ignored his throttle inputs because
the aircraft was flying at the pre-set airspeed and attitude that it was set
to fly for the fly-by (Landing) Proper procedure called for the pilot to
depress the GO-AROUND (GA) switch on the throttles if he didn't want to
land. That in turn would "disconnect" the auto-land feature (which was
believed to have been in use) and the throttles would have advanced
automatically or reacted normally to manual throttle movement that would
allow take-off power. But when set in the "landing" mode, the flight
computer commanded all power authority to the engines and it didn't matter
what physical position the throttles are moved to."
"At the time of impact with the trees, the pilot had the throttles all
the way forward but he didn't know enough about the flight control system to
know he needed to depress the GA button to go to manual throttle control. In
a Boeing for example, the aircraft he was previously rated in, when you push
the GA button, it commands the flight director V-Bars to the proper position
on the attitude indicator and automatically advances the throttles if you
had the auto-throttles on, or you could move the throttles yourself and you
get whatever power you want. If you forgot to depress the GA button, you
could still advance the throttles and the engines will still give you the
power you're commanding, you just won't have the proper V-Bar indications on
the attitude indicator."
"The Airbus is quite different. The throttle isn't connected to a cable
so the computer senses movement on the throttle and the computer determines
if it's appropriate to give the pilot what he / she is asking for before it
moves the actuators and gives you power. Push the right buttons and it will
most the time. That's what we teach here at United regarding the
consequences of pilot's not knowing the systems they operate."
"Now you know the real story." |