LOT B763 near Toronto on Jun 19th 2009, severe turbulence and unreliable airspeed

LOT B763 near Toronto on Jun 19th 2009, severe turbulence and unreliable airspeed

www.avherald.com

The airplane encountered "severe turbulence at high speed" and started to deviate significantly from assigned altitude. The crew reported later, that their airspeed had become unreliable and requested to divert to Toronto

(visit the link for the full news article)


Related News Links:
www.pprune.org

This seems a similar scenario to AF447 although different aircraft.
Read the link below for opinion on lack of media coverage, interesting perspective (A vs B).

"This particular incident seems to have largely avoided media coverage.

One would have thought that considering recent events, a widebody aircraft forced to descent while experiencing severe turbulence and unreliable airspeed would be of particular interest.

I'm sure that if this had been from manufacturer 'A' rather than manufacturer 'B' there would be media hysteria"

www.avherald.com
(visit the link for the full news article)

Manufacturer A being Airbus?
and B being Boeing?

i do agree though, that these incidents even if resulted in little more than an "early stop", are extremely important as far as aviation safety is concerned

i personally would really like to know what caused the airliner to lose airspeed..thats pretty bizarre

engine problems from turbulence ? it may be possible

reply to post by muzzleflash

i personally would really like to know what caused the airliner to lose airspeed..thats pretty bizarre

If I may chime in, when you encounter unexpected turbulence like that (especially if it's CAT, or 'Clear Air Turbulence', your immediate response is to a) slow down to what we call max turbulence penetration speed and b) change altitude to hopefully get out of the area of turbulence and c) turn on the Engine ignition switches. As to changing altitude, it's far faster to descend than to climb.

In cases like the LOT incident, airspeed WILL fluctuate wildly, so we use a combination of power settings and pitch attitude. The engines will be normal, mostly, although if the intake airflow is disrupted excessively you might experience a flame out, hence the selection of Ignition to 'Continuous' as a just in case.

After a violent encounter like that it is proper and prudent to divert to an alternate destination, if available...and Toronto was.

Is there a reason why the engine ignition switches aren't always set to "on"?

Originally posted by Mogget
Is there a reason why the engine ignition switches aren't always set to "on"?

Yes, it will wear out the ignitors in no time, that's why it's limited to takeoff and landings (and non normal situations where a flameout can occur).

There has been fatal crashes before with blocked pitot tubes with boeing aircraft, confusing the pilots.

Birgenair Flight 301 Boeing 757-225
Aeroperú Flight 603 Boeing 757-23A

It wasn't a fault with aircraft it was mainternance issues.

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 crashed first.

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]