Author Topic: Etihad Mayday Lost Airspeed Audio Edited  (Read 13872 times)

Offline philip

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Etihad Mayday Lost Airspeed Audio Edited
« on: November 23, 2013, 03:34:56 AM »
I took 3 of the ATC's and put them together



Offline phil-s

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Re: Etihad Mayday Lost Airspeed Audio Edited
« Reply #1 on: November 24, 2013, 05:58:17 PM »
Recall another thread with people registering surprise that Air France kept saying "panpan" after each call sign (more like "pnpn")? Well, here's Eithad doing it also. I think it may even be standard in non US/Canada airspace.

Offline Joseph Alexander

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Re: Etihad Mayday Lost Airspeed Audio Edited
« Reply #2 on: November 30, 2013, 06:05:42 AM »
Since all three stages of emergency notification are derived from the French, it is quite possible the Air France pronunciation is much closer to the original than their English accented versions.

Offline aimana007

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Re: Etihad Mayday Lost Airspeed Audio Edited
« Reply #3 on: November 30, 2013, 01:25:33 PM »
This may be a dumb question, but with all the pitot tubes I see hanging on the nose of every commercial Boeing & Airbus jetliner I have had the pleasure of boarding.. how does such a (triple, IIRC) redundant system fail so completely?

Also, how do you hit your reference (V) speeds with no airspeed indication? GPS ground track speed is available on the flight director display (I think), but, to calculate airpseed you'd have have winds aloft speed/direction, and bust out the old E6-B to try and calculate something even remotely resembling an accurate airspeed.

http://flightaware.com/live/flight/ETD473/history/20131121/0155Z/YBBN/WSSS
EDIT: Above referenced Flightaware entry for this flight is inaccurate, news reports show a divert/return to Brisbane:

http://blogs.crikey.com.au/planetalking/2013/11/21/etihad-calls-mayday-in-brisbane-emergency-a330-landing/

In re: Pitot failure. Icing? Nah.. pitot heat should eliminate that rapidly. Maintenance issue? Eti is genreally regarded as a "premier" airline, and has a good service/safety record from what I can see. Blockage? Really, ALL the pitot tubes blocked in one go?? statistically improbable. I'd really like to see the incident report when it's released..

A330 tube locations & functions:
« Last Edit: November 30, 2013, 01:44:40 PM by aimana007 »

757-rules

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Re: Etihad Mayday Lost Airspeed Audio Edited
« Reply #4 on: November 30, 2013, 07:44:48 PM »
From another website I read the captains pitot tube was damaged (in foreign language that can also mean inop) and it would be a bit confusing doing the crosscheck on instruments. To eliminate the confusion they might have had a discreet channel with ATC available, or they used the groundspeed shown on the navigation display (which would be computed from GPS).

All is speculation though....

Offline InterpreDemon

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Re: Etihad Mayday Lost Airspeed Audio Edited
« Reply #5 on: November 30, 2013, 08:33:18 PM »
Although they could have used ground speed combined with reported winds, it is most likely they simply used known power, configuration and attitude to keep airspeed within a safe envelope, as any good pilot not overly dependent upon instrumentation can do, especially in visual conditions close to the ground.
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Offline joeyb747

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Re: Etihad Mayday Lost Airspeed Audio Edited
« Reply #6 on: December 03, 2013, 04:41:52 PM »
This may be a dumb question, but with all the pitot tubes I see hanging on the nose of every commercial Boeing & Airbus jetliner I have had the pleasure of boarding.. how does such a (triple, IIRC) redundant system fail so completely?

The only dumb question is the one you don't ask!  :wink:

I can think of several instances where total Pitot/Static System Failure has occurred for various reasons. To name a few:

-Bergenair 301, a Boeing 757-225 that crashed in February 1996 off the coast of the Dominican Republic due to a single pitot tube blocked by a mud dauber wasp nest.

-Aeroperu 603, a Boeing 757-23A that crashed in October 1996 after departing Lima, the cause was determined to be tape left on the static port after the aircraft was washed.

-Air France 477, an Airbus A330-203 that crashed into the Atlantic in June 2009 off the coast of Brazil. The cause of this crash has many factors, but the sequence of events started with inconsistencies in airspeed readings, likely due to the aircraft's pitot tubes being blocked by ice crystals after the heat system malfunctioned.

So, to answer your question, sometimes it's nature, sometimes it's human error, sometimes it's mechanical failure. A "lost" instrument reading my not be "lost" all together. If the Captain's side is reading different then the F.O.'s, they may not know what is the true reading, if either of them.

According to The Cambridge Aerospace Dictionary, the definition is as follows:

"PITOT/STATIC SYSTEM: INSTRUMENTATION SYSTEM FED BY COMBINATION OF PITOT PRESSURE AND LOCAL STATIC PRESSURE, DIFFERENCE GIVING DYNAMIC HEAD AND THUS ASIR (air speed indicator reading)."

In other words, the system relies on the difference between the two to come up with the data the instrument is to display, and when one part of the equation is missing, it can and will display incorrect information to the point of being deadly.

Hope this helps...
« Last Edit: December 03, 2013, 05:03:09 PM by joeyb747 »
Aircraft Mechanic