AF447 wreckage found
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IMO it's just plain stupid that a multi-million machine with humans inside have to rely on a "stupid" analog tiny tube, even worst without redundancy or a reliable alternative.
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If you're about to invent something better than a pitot-tube you'll be a rich man. Even the space shuttle measures its speed with pitots while in the atmosphere...
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Hi,
It's not new ....
Aircraft have been flying around for decades with pitot tubes which haven't iced up - how come there's been a problem with these ones?
Décembre 1995 : TFU 34.13.00.005 (annexe 1). Airbus fait le constat de l’insuffisance de la
certification des sondes Pitot. Les cristaux de glace obstruent les sondes ce qui provoque une
dégradation sévère du calcul des paramètres de vol.
certification des sondes Pitot. Les cristaux de glace obstruent les sondes ce qui provoque une
dégradation sévère du calcul des paramètres de vol.
December 1995: TFU 34.13.00.005 (Annex 1). Airbus made the finding of inadequate
Certification pitot probes. Ice crystals obstruct the probes which causes
severe degradation of calculating flight parameters.
Certification pitot probes. Ice crystals obstruct the probes which causes
severe degradation of calculating flight parameters.
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pitch + power
I am a little perplexed.
What has happened to the basic law of flight:
Attitude.
Power.
Trim.
Point the aircraft at zero pitch attitude,
apply cruise power
unload any stick force (trim)
and no matter what a cb throws at you it cannot sustain an over speed nor an under speed.
What has happened to the basic law of flight:
Attitude.
Power.
Trim.
Point the aircraft at zero pitch attitude,
apply cruise power
unload any stick force (trim)
and no matter what a cb throws at you it cannot sustain an over speed nor an under speed.
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@ RobBamber
Didn't the PF acknowlege reaching level 100?
Quote from http://www.bea.aero/fr/enquetes/vol....ai2011.en.pdf:
At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred".
That's roughly 25000' from the level 2 min before (350):
"At around 2 h 11 min 40, the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped.(...) The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees."
It seems to me that, given no visual cues nor instrument readings, a pilot flying by the seat of his pants may interprete a pitch up attitude coupled with such a horizontal deceleration as level flight.
Quote from http://www.bea.aero/fr/enquetes/vol....ai2011.en.pdf:
At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred".
That's roughly 25000' from the level 2 min before (350):
"At around 2 h 11 min 40, the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped.(...) The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees."
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Here's an observation which may or may not be relevant. The plane decelerated from horizontal Mach 0.82 to 107 knots over a period of 3 min 30s. By my estimate that is an average horizontal deceleration of around 0.1g.
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The Guardian has cut ‘n pasted directly from an earlier post in this thread.... Air France crash inquiry details pilots' battle for survival | World news | The Guardian Attributed to "Anonymous A330 Pilot”
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Judging from the reports of what happened in the cockpit, one is left with the impression that without automation both pilots were seemingly bemused at events and helpless. This is not surprising, since with many airlines basic instrument flying ability has been relegated to low priority in favour of competency at autopilot operation. Even Jet Upset training is not a serious subject in simulator training. Five minutes at the most and once a year is the norm.
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Unless I missed it, nobody seems to have mentioned that the original worst-case theory--that the airplane flew into the mother and father of all ITCZ thunderstorms because it was radar-blanked by a line of cells between it and AF447--no longer seems to hold water.
Certainly 447 flew into weather that created an unusual kind of supercooled, high-altitude icing that suddenly affected the Pitots, but the CVR transcript doesn't mention anything that might be interpreted as turbulence upset--only the apparent impossibility of dealing with multiple fault warnings and anomalous displays.
Certainly 447 flew into weather that created an unusual kind of supercooled, high-altitude icing that suddenly affected the Pitots, but the CVR transcript doesn't mention anything that might be interpreted as turbulence upset--only the apparent impossibility of dealing with multiple fault warnings and anomalous displays.
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Too Many Laws
Seems like too much pilot training is spent on understanding five control laws: Normal, Alt 1, Alt 2, Direct, Abnormal. Are there more?
Makes me wonder if more than two are needed or desirable: Normal and Direct. I don't understand why the AP/AT had to drop out of Normal for flaky airspeed. At least not in cruise. It could hold pitch and power for awhile without dropping out, giving the pilots time to analyze the situation without having to hand fly, too.
Makes me wonder if more than two are needed or desirable: Normal and Direct. I don't understand why the AP/AT had to drop out of Normal for flaky airspeed. At least not in cruise. It could hold pitch and power for awhile without dropping out, giving the pilots time to analyze the situation without having to hand fly, too.
In the sim if all the pitots are iced at the same rate the aircraft will stay in Normal Law as there is no disagree. In a climb the aircraft will eventually overspeed and an nose up input made leading to an uncontrollable climb leading to a stall and very low airspeed. Not a very pleasant scenario.
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stall warning
Why would the stall warning be programmed to stop if the AOA indication is deemed unreliable below 60kts? Doesn't it seem intuitive that if a 200t jet transport has an IAS of < 60kts (and WOW says the plane is in the air), then it MUST be stalled, regardless of the AOA reading?
Then again, we have our iced pitot scenario, with IAS of less than 60kts.
Then again, we have our iced pitot scenario, with IAS of less than 60kts.
Last edited by Flight Safety; 30th May 2011 at 16:26.
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Der Spiegel on AF447
New article on Der Spiegel in english, including a quote from captain Dubois after entering the cockpit, that was not in the BEA-report, but comes from sources close to the investigation team.
Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International
Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International
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"The aircraft pitched up steeply and decelerated from cruise speed to a virtual standstill in the first 30 seconds or so, then went from about 80 mph up to over 100 mph down. None of that would have been interpreted as normal horizontal flight."
There is some confusion among posters here, and in the press, about the flight path. The pitch attitude is reported to be around 15-16 degrees nose up, and the angle of attack to be 35-40 degrees. This translates to a flight path angle of -20 to -25 degrees. If the vertical speed is around 10,000 fpm (~100 knots), then the slant speed has to be the vertical speed divided by the sine of the descent angle, or somewhere around 250 knots. This is the true airspeed. The airplane was not fluttering down vertically like a leaf, and its foward speed was not 60 knots or 107 knots or whatever. As the flight track graphic in the interim report (vertical dimension exaggerated) shows, it was in a stalled glide with a comparatively moderate angle of descent and a good deal of forward speed.
There is some confusion among posters here, and in the press, about the flight path. The pitch attitude is reported to be around 15-16 degrees nose up, and the angle of attack to be 35-40 degrees. This translates to a flight path angle of -20 to -25 degrees. If the vertical speed is around 10,000 fpm (~100 knots), then the slant speed has to be the vertical speed divided by the sine of the descent angle, or somewhere around 250 knots. This is the true airspeed. The airplane was not fluttering down vertically like a leaf, and its foward speed was not 60 knots or 107 knots or whatever. As the flight track graphic in the interim report (vertical dimension exaggerated) shows, it was in a stalled glide with a comparatively moderate angle of descent and a good deal of forward speed.
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But nothing is as fast for a basic instrument scan as an altimeter pointing at 12 o'clock and the VSI at 9 o'clock. Instant awareness of your altitude and sink rate.
IMO the tape display, while nice with the low and high speed buffet tapes on the airspeed, cannot compare to the rapid awareness you have with round dials and moving needles.
IMO the tape display, while nice with the low and high speed buffet tapes on the airspeed, cannot compare to the rapid awareness you have with round dials and moving needles.
I agree with your basic remarks.... Not for nothing do glass engine instruments still show replicas of the original 'clocks'.
But the altimeter is a bad example, with the old "hours-minutes-seconds" clock scale (you know what I mean) not being all that fast and easy to read, and being implicated in several incidents (I don't remember accidents off-hand). Which is why the numerical 'drum' scale was added, even before we went to 'glass'.
Unfortunately, with the conversion to 'glass', just about all the moving pointers disappeared.
Humans are analog oriented.... For all the non-pilots on here.... just try to imagine playing a video game where all the game information is in the form of numbers on the screen.....
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Doesn't it seem intuitive that if a 200t jet transport has an IAS of < 60kts (and WOW says the plane is in the air), then it MUST be stalled, regardless of the AOA reading?