Two A330 airspeed and altitude incidents under NTSB scrutiny

Its going to be difficult to put together what happened to the AF flight without the data recorders. I wonder what the relative cost / benifit ratio would be to have the aircraft send data in microbursts every few seconds as aback up?

The US National Transportation Safety Board today said it is investigating two recent incidents involving possible malfunctioning of airspeed and altitude indications in the cockpits of Airbus A330 aircraft.

Four days after the 1 June crash of an Air France Airbus A330 off the coast of Brazil, French investigators confirmed automatic messages transmitted by the aircraft show the jet was experiencing conflicting airspeed information from onboard sensors.

The first incident under NTSB scrutiny occurred on 21 May, and involved a TAM A330 operating from Miami to Sao Paulo, Brazil. The A330 experienced a loss of primary speed altitude in cruise. Initial reports indicate the crew observed an abrupt drop in indicated outside air temperature followed by the loss of the air data reference system. Both the autopilot and autothrust disconnected, and speed and altitude information were lost.

NTSB says the TAM flight crew used backup instruments, and primary data was restored in five minutes. The flight landed in Sao Paulo with no further incidents.
www.flightglobal.com...

Right... I'm thinking "out loud" as such here, so don't be surprised if I'm neglecting something fundamental and writing rubbish as a result...



GPS is based on triangulation of satellite signals... therefore a 3 dimensional fix in space can be achieved.... correct?


Which means both speed and altitude (relative to local average sea level based on geographical map) could be derived for any aircraft.


Is a guidance system based on this concept already used on aircraft? (I'm not an instrumentation person, and know little about it!) If not, it would be a good backup to pitot probes.

Surely Tomahawks use GPS guidance already for placement, how do they follow terrain (altitude above sea level)? Their own radar? Mapping based on GPS?

[edit on 13/7/09 by kilcoo316]

GPS'll only tell you your ground speed, which with head- or tail-winds will be significantly different to actual air speed.

This could prove critical, especially towards the top of the flight envelope.

reply to post by FredT

The "conspiracy" theory, as some may be aware, is that these planes are getting shot down. Some say, by electromagnetic pulse-type weapons.

The theory goes that they get shot down either because one of the power groups decides it needs to flex its muscles, or is trying to send a warning to one of the other power groups, or is retaliating for one of its planes being shot down. This is a pretty far-out theory, as far as I can tell. If they could get those flight recorder gadgets to work better and be easier to recover, they might be able to learn more, but of course if what they learned was too embarrassing, they wouldn't release the data anyway.

I think the only solution that would get closer to the truth would be to have a technology that would continuously monitor a plane the whole time it was aloft and send the data as a public broadcast that any old joe could pick up and decode. Then there would be no way for a government to lie about what was recorded on the flight recorders, and no excuses like "oops, it sank" or whatever, which seems awfully lame to me in this day and age.

Originally posted by Poon
GPS'll only tell you your ground speed, which with head- or tail-winds will be significantly different to actual air speed.

This could prove critical, especially towards the top of the flight envelope.

Absolutely correct.


Next question; does air weather radar give indications of system front airspeeds? (i.e. wind)

I don't think it can give a reliable indication of system front speeds - to the best of my (limited) knowledge it relies on the water content of the weather for a return.
I can see where you're going with this though.

You can get airspeed by finding the AoA required to maintain 1g at your specific weight. Only problem is the pilots have to look up the charts. They should develop a backup function to do it automatically as the aircraft always knows how heavy it is. This system would be extremely basic compared to anything else in the plane.

[edit on 15/7/2009 by C0bzz]