reply to post by deckard83
Actually, deckard, two similar but slightly different reasons.
BergenAir had one (out of three) blocked pitots, although never recovered it is suspected that a species of wasp had built a nest. However, the other
two worked perfectly, and gave valid data to the First Officer and StandBy Airspeed Indicators. Unfortunately, the Captain chose to fly that leg, and
it was his pitot that was blocked, hence the left
ADC was receiving erroneous information, and triggered many false and conflicting warnings.
If they had just disconnected all automation, and examined and compared instruments, they would have determined the problem.
You're right, it was a maintenance issue, since the airplane had sat for three weeks without protection, such as pitot-tube covers. AND, the
contract Maintenance personnel did not do a thorough check.
Aeroperu, on the other hand, had the static ports covered with tape, as the airplane had just been washed, and they forgot to remove the tape.
Contributing factor was night time, with no well-defined natural horizon. However, proper pitch and power settings could have been used, whilst
ignoring the erroneous airspeed indications. They almost made it, another airplane was going to fly formation with them back to landing, but they
edit: Interesting to point out that unreliable airspeed is not an 'automatic crash' scenario! It is a matter of training and experience levels
that make the difference.
[edit on 6/26/0909 by weedwhacker]