opherben -- We are getting to the stage where electronic instrumentation and control will be more reliable than humans. We are not there yet...too many things that can go wrong. Mechanicals, electricals, electronics, passengers(!) and GPS which is only available to us at Uncle Sam's pleasure. It will happen in time even if none of us reading this are alive to see it happen. So might we not expect this to be introduced by evolution while de-skilling pilots?

Regarding other traffic on the Atlantic that night, I wonder how much useful weather info was being passed on 123.45, by the earlier flights, in order to help fellow crews, on the same route as AF447. Many years of Atlantic crossings taught me that AF and LH seem to be the two airlines hesitant at giving, or receiving such info,or at least, they never replied!!!
We need to look after each other in this industry with all the pitfalls!...Monitoring Data and 121.5 does use up spare radios however!

AutoTrim?
 

Hi there,

german news outlet "Der Spiegel" has an interesting story about a german aerospace engineer (Professor, that is...) who experienced some strange (disturbing) behaviour in the simulator. Read yourself (english version):

Air France*Catastrophe: Victims' Families Propose Grounding All*A330s - SPIEGEL ONLINE - News - International

According to flight global, automatic stab trim should have been inhibited when alpha > 30 degrees - Stalled AF447 did not switch to abnormal attitude law but it was not.

So is this saying that the flight control system continued to do what was asked of it - trim for attitude / 1g and therefore trimmed in the stall - when it should have dropped out?


Edit: Isn't 30 degrees AOA..rather high?

As per the SPIEGEL article the relatives are basically demanding from a french judge to ground all A 330 and 340 worldwide until software issues regarding the trim of the elevator are resolved and to prevent further accidents.

As a SLF I find that somewhat mind boggling. I never had issues flying with the Airbusses but I am getting a bit more skeptical... I would like to know if any of the major carriers (BA, AF, LH, KLM, USAir, UA Delta) are analyzing the issue at hand...?

AoA at less than 60knots
 

Guys maybe a stupid question:

How does the computer know that airspeed is less than 60knots so as to sound off the stall alarm if the airspeed is unreliable?

What if the plane is stalled at 80knots airspeed and the airspeed is unreliable 'showing' 50 knots. Will the stall alarm sound off?

AoA sensor is a small flap exposed in the airstream, how does the output of it in the cockpit (stall sound) is conected to an airspeed instrument that can be unreliable?

Can anybody expalin why AoA is not available under 60knots? If for some reason speed (reliable or not) is less than 60knots then there is no AoA input for the computers?

I'm obviously not a pilot, but I haven't understood the AoA unavailability under 60knots.

Hi,

Cause Airbus decided it will not be available cause their planes never go (in air) at this slow speed ............

I loved your post, "The Shadow". I agree with you.
As I have wrote a number of pages back, there are a number of questions waiting to be answered:

Why did BEA apparently decided to disclose, only a part of the information?

Barnyard Logic
 

Go outside, farmer, and look at the weather vane on your barn. Note, it aligns into the wind because its tail has more area than its point, which is only needed for static nose/tail balance. Note that it also has a lightning rod above it.

Angle of Attack is vertical measure of relative wind. The AOA sensor is just a high priced vertical weathervane, as seen previously on this thread. It's high priced because it has to be reliable in all imaginable weather and flight conditions, including direct lightning strikes or sweeps. It has some inertia and frictional damping to prevent flutter in all possible conditions.

Therefore, just as your barn's weathervane can be erroneious below about 10 knots wind, the AOA sensor cannot be trusted below about 60 knots.

You got a better AOA sensor? If not, why are you criticizing lack of Stall Warning below 60 knots?

If you don't understand this, maybe your time would be better spent shoveling out the barn.

"a precise speed is critical. Just 15 kilometers per hour (9.3 mph) faster or slower and the plane can stall...." Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International Question -- at the top of a big storm cell, in that kind of turbulence, isn't the air around the aircraft changing direction faster than plus or minus 15 kph rapidly? what is the aircraft/pilot/computer detecting?

Hi,

In Bussiness Week ....

Air France Crew May Have Faced Baffling Data in 2009 Crash - Businessweek

Yaw String, the crew went to SELCAL mode at 0135. After that time, they did not reply to several queries from ATLANTICO. They thus would have missed any communications between ATLANTICO and the LH ahead of them regarding its deviation on encountering the MCC.

Was it prudent behavior going to SELCAL mode flying into a SIGMET area, and after receiving the following from dispatch?

The yet-to-be-released portion of the CVR may have the answer.

The PF had performed five rotations in the South America sector since arriving in the A330/A340 division in 2008, including one to Rio de Janeiro.

The PNF had performed 39 rotations on the South America sector since arriving in the A330/A340 division in 2002.

The Captain had carried out sixteen rotations in the South America sector since he arrived in the A330/A340 division in 2007.

The data released to date do not indicate how many rotations occurred during the different seasonal variations of ITCZ activity in the South Atlantic..

SaturnV:
SELCAL mode is not a question of being prudent or not. Its a question of VHF comm range. When we go into SELCAL we normally keep the last VHF comm freq selected until loosing full contact with the previous ATC and then select 123.45 on VHF 1. (VHF 2 on 121.50).

Not sure I understand that comment Saturn - Are you suggesting they should have maintained a continuous listening watch on HF...?

I do agree with Yaw String - we all need to help each other via VHF on the Oceanic Sectors......

Thanks Saturn V for the data.

Some alarmingly uninformed questions about fuel by other posters. To clarify transport aircraft always carry contingency fuel for deviations. My assertion is that the flight before and the flight after had prior to departure filed a modified flight plan to deviate around the storm. In doing so they took on extra fuel in addition to the contingency fuel. Any talk about the head office refusing a Capt extra fuel is absurd.
It is remarkable that AF447 showed no signs of significant deviation up to the point of the incident. IMHO this implies they were unaware of the storm system at least until they were in it. Did they get the wrong pre flight weather or simply omit it?
I don't believe any transport pilot would choose to take a center line path through a large storm given advance notice and the ease of a deviation. Would not having known of the storm also tie in with the bewildering fact that the Capt took rest immediately before entering the storm. I would want to look at a transcript of the pre-flight briefing to see if the storm was mentioned. Relatively minor mistakes early on (e.g. pre-flight) can snowball events down the road.

Gordon Vette was banging on about that.....few if any accidents/incidents occur due to one factor. They are invariably due to a number of factors, most of which would not, of themselves, cause anything remarkable to happen.

For Graybeard and about AoA Probes and indications
 

Graybeard, in re "better" AoA indicators. I'll suggest to you that the US Navy has been using one "better" (actually, I doubt it's any better) from before I started flying which functions reilably at airspeeds below 60 knots. (There is one on the T-34C Trainer that works as you describe ... a weather vane in the horizontal plane. See also AoA probes on various Navy jets).

I don't think it's the probe that's the issue, but a software decision on signal processing. You could do what you need to (no stall chirp on the ground) with a WoW switch (already have one on the bird, yes?) without artificially clipping the AoA signal when in flight.

Your comments, sir?

About Pilot Training and Simulators
 

Note: absent FDR data, how did he recreate that crash??? :confused:

What is unknown to me is how well the sim replicates stall for that aircraft. A number of sage Airbus pilots, who have also taught in sims, have pointed out (in the Tech Log Discussions) thta lacking the data points from extended flight test, programming data points into the sim for stalled or other "outside the envelope" flight conditions is a bit of a guessing game. It can lead to negative training due to anomalies NOT present in the aircraft being experienced in training in the sim.

While Hüttig doubtless understands this, please consider the report on his findings to be provisional. See also that the champion for this position is an attorney involved in an action ... tread with care here.

A few other points.

Pattern is full made an important observation a few pages back about displayed speed. For an interval there (about a minute?), what is on the FDR may not be the airmass flow that the wings, rudder, the THS saw. So, what is on record for BEA to analyze has to account for "data" points that are known to be erroneous for some of the time before and after the upset.
As above, if it was indicated, and the indicators were dodgy (iced probes) at that point, 60 kts may not have been what the airfoil was experiencing.
Seems to me that way as well, see my previous response to Graybeard.
It is subordinate to stalling in the first place, but yes, it seems to have been unhelpful at a critical time, for the pilots on the flight deck.
Agreed, silence it with a WoW switch, as you won't fly an AB330 under 60 knots too often. :)
Agreed. With ISIS NOT having VSI, the back up may be missing a vital cue. (Or, I read my ten-year-old display diagrams incorrectly).

Thought for Flight Saftey: confusion looks to have begun early in the event, when the PF had the A/P off and ended up in a climb. That looks to me like a symptom of primary instrument scan breakdown. If, and I repeat IF, his attitude indicator (pitch and roll / artificial horizon) was working, it appears that PF made a transition while not using attitude indicator as primary scan. Since we don't know what PF was seeing, that is a provisional hypothesis, quite possibly wrong.
I take your point, add to my provisional hypothesis, training/proficiency programs, and the Admiral's idea about working pilots out to test their limits. I wonder at the confidence the public have in airline companies doing what is right.

Given the generally successful departure and arrival rates, maybe the public is willing to accept the very, very small risk of this "imnperfect storm" of events creating a flying catastrophe.
What is the point of that? AoA is a flight parameter, if not a primary instrument scan item in all flight regimes. How hard is it to make it readable as a cross check, or in the corner of one of the displays?

Just change the page and location the computer is sending it to.

If you have a warning "revert to manual trim" can you not also find some real estate for "AoA = XX.X? "

This does not seem hard, but actually it is. Figuring out where in a display package this goes is a non-trivial process, since there is X area for display and a lot of different information that pilots use or need.
Yes. If your pitch rate is too fast, you can change your AoA too fast and either create a stall, or an accelerated stall, while pulling out of a dive.

The latter killed a colleague of mine a couple of decades ago.

More questions: Doomed Flight AF 447: Questions Raised about Airbus Automated Control System - SPIEGEL ONLINE - News - International

EDIT: Bad info.

ECAMS:

As I understand the FC diagrams, Alt Law has auto trim for elevators and THS, you go to manual trim in Direct law for the THS. If I am reading that wrong, please advise.

From the diagram, it appears to me that elevator trim may not be operating in Direct law, but I may be wrong on that.

Here are the words ... (from an out of date summary of A 330 systems)

Alternate Law

• No change for

1. The lateral control is similar to normal law (no positive spiral stability is introduced).
2. Characterized by a direct stick-to-roll surface relationship which is configuration dependent

•

- pitch attitude : lost
- high speed : replaced by static stability
- high angle of attack : replaced by static stability
(Vc prot. Law) + aural stall warning when

- low energy : lost

Direct Law

• No change for

•

Conventional aural stall and overspeed warnings are provided as for Alternate Law.
• Main operational aspect :

- manual trimming

@Lonewolf: you are right. In ALTN LAW there is auto THS.

Low Speed Stability will attempt to pitch the nose down to maintain just above Vls, but the pilot *CAN* override this (maybe that is why the PF was pulling up - he was stopping the nose from dropping in the belief they were flying and the systems thought they weren't due to the low airspeed reading?).

ECAM: this is the first time I have understood that feature of the system, Low Speed Stability.

Quote:

---

Low Speed Stability will attempt to pitch the nose down to maintain just above Vls, but the pilot *CAN* override this (maybe that is why the PF was pulling up - he was stopping the nose from dropping in the belief they were flying and the systems thought they weren't due to the low airspeed reading?).

---

I'll post a link to your post in the Tech Log discussion, since I have yet to see this man-machine interface issue raised in the deluge of posts on that sub forum. It may have been mentioned, but not in the concise way you just did.

PF is in ALT Law, so hand flying, which means flying a bit by "feel" (is this right, AB drivers?)

I have flown conventional aircraft in out of trim conditions, so I think I know what "feel" might be in his hand, and induce a pitch up that it takes a bit of scan to realize is happening. This might explain that initial "zoom" at 7000 fpm and initial "correction" to about 700 fpm climb ... thanks for switching the light on for me. :)

Hi,

This ... ?

Aquadalte,

The recent BEA note indicates that the PF briefed the PNF who had arrived at the cockpit that at some time before 1 h 59 min 32 s that logon with DAKAR had failed. (At least 21 minutes before estimated changeover from ATLANTICO to OCEANIC DAKAR which was at 2 h 20 at the TASIL waypoint.) LH507 (believed to be the flight with AMDAR) monitored 121.5 the entire flight and never heard any communication from AF447.

The PF also briefed the PNF at 2 h 00 that the ‘little bit of turbulence’ just experienced would be similar to what would be experienced ahead.

Tim Vasquez concludes, “Based on the soundings above, my conclusion is that the maximum cumulonimbus tops were 56,000 ft with an equilibrium level of 47,000 ft, representing the tops of most parts of the MCS except near the edges.”

So CVR transcripts of any conversation on what they were seeing on their radar displays will be interesting.

I'll leave it to others to comment on jumping ahead on a frequency change 21+ minutes before one arrives at the boundaries of the FIR.

xcitation

I seem to remember that the flight plan for AF447 did not list Paris as it`s final destination but something closer along the way (toulouse?) and Paris as an alternate. The logic, so it was said, would be that filing Paris would have left them with less than the allowed contingency fuel and that through this trick, they could safely go with the amount of fuel on board and decide closer to French shores to use the contingency fuel to go to Paris.
Can anyone confirm that that was the case? And if so, what would that say about their ability to deviate around the cell and still make it to Paris. A refuelling stop in Toulouse would certainly be an embarrassment.

Speaking of Tim Vasquez: If you browse over to his web site you'll note that he has made some data modifications, today as a matter of fact, which uses some of the data supplied by BEA on 27 May.
As usual it makes for some very interesting reading.

However, and again using data provided by BEA, he corrlelates that data with weather data available at the time.

This is the new, updated, weather chart and the flight path of AF447:

http://www.weathergraphics.com/tim/a...s-0145-ann.png

Guys.... a little knowledge is a dangerous thing:

Saturn

Why are you claiming they're "jumping ahead on a frequency"? They are talking about their datalink or CPDLC / ADS, not radios. That comment in the handover means that haven't yet got CPDLC logon with Dakar ATC (possibly because it's too early for Dakar to "accept" them). As far as HF frequencies are concerned they may well have still been on SELCAL watch on the Atlantico frequencies...the fact that Atlantico couldn't raise them could just mean they were in an area of poor HF reception.


ap08

It's called a reclearance operation....been done for years in Longhaul.....I plead guilty to doing this, as I guess do many of the grey haired Longhaulers here. It's no big deal as long as you don't reclear onwards beyond your enroute alternate without the fuel to do so.

I'm not able to find details of his simulation a year ago online - I wonder if it includes the zoom-climb to FL380 ?

Did find in here picture of the Professor suggesting a position for the captain?

AirFrance.pps

so if they filed for Toulouse, intending to go on to CDG, I assume that a deviation might have put them into a situation where they would end up having to refuel before getting to Paris?
could this have begun as a severe case of get-homeitis?

Wiggy, although it did not affect the flight, Brazilian ATC had omitted DAKAR from the AF447 flight plan. (Whether it affected the search is probably an open question at this point.)

It could equally have been a pragmatic approach to getting out of GIG in the first place. I haven't seen the performance figures for the flight but they may not have been able to lift the planned payload and "full" GIG-CDG fuel out of GIG...they might have been able to carry fuel for GIG-CDG plus a little bit of extra, but not enough to give them the legal amount of contingency, or buffer fuel, needed at the start of the flight. One option would be to come back on a windier cooler day, another dump freight or passengers...:ooh: , another one would be to fill up as much as possible, file a plan for say GIG-TLS - which given the shorter track could then mean you have full legal contigency fuel for that sector, so all legal, above board, a recognised procedure and safe.

Once you approach TLS you look again at fuel on board and decide wether you have enough in tanks to overfly TLS and continue to CDG with legal reserves or wether you don't, in which case have to do a tech stop.

It's not a technique used as much these days as it was 20-30 years ago but it still has it's uses if you're short of performance, and it's perfectly legal, the critical thing is you don't press on beyond the en-route alternate without fuel to so so....sadly the crew of AF447 never got to make that decision.

SoaringTS...you beat me to it, Rgds.

A weather deviation decided in time (not in a panic) costs peanuts in fuel. Cut that idea.

wiggy

I understand the idea and yes, it does make sense when you're streching it a bit. my question was: how long a deviation could they have made before TLS would have been their guaranteed next stop?

We've seen many cases where pride made people make bad decisions.

Looks like a lot of posters do not have a clue about CPDLC operations, hence the comments about jumping ahead on a frequency, no CPDLC log on yadda, yadda, yadda.

Agree with wiggy, a little knowledge is indeed a dangerous thing. With the data released in dribbles, I cannot help but think that we are all being led into posting things which will help interested parties to cover their arses.

We might be doing the dead crew members a great disservice in our rush to pontificate and show off " armchair " style our great flying skills and systems knowledge.:hmm:

Training Training Training...
 

There is no mystery.

1/ a pilot nose up
2/ he stalled his plane and didn't alert the captain nor did he communicate
3/ he didn't recognize his fault although his instruments gave him all the necessary information (the lack of speed data is a consequence of the stall not the cause)

That's all.
Pilots are here to pilot the planes that are given to them (OK : their opinion is welcome).

I play golf : every 3 month I need 3 hours of practicing my 3 iron to be able to do something with it.

To pilot is a sport : it needs training and training and training.

That's why there are captain and cadet. Champions and losers.

Bluesideup
 

Just as a caveat, I have read most but not all the approximately 1300 posts on this thread. I have yet to read anything concerning the “Thrust Lock Mode” of the autothrust system. If it’s been previously addressed bear with me. For continuities sake, I’m starting at square one of how the system is supposed to work. As for my background, I flew the A-330 for a year and a half as a Captain prior to my retirement (60th birthday) about 1 year ago.

The problem with the autothrust system being inop is the way they interface with the thrust levers. When autothrust is in use the thrust levers are selected to one of 4 detent positions (TOGA, FLX/MCT, CL and IDLE) and don't move even though the engines may be delivering different amounts of thrust to maintain the selected mach/airspeed number. During cruise, they are in the CL or climb detent and have a power range from idle to max climb thrust. CL is the detent the thrust levers stay in 99% of the time. It is used for climb, cruise, descent and approach. To manually control the thrust levers you need to take them out of the CL detent, match the EPR setting with the thrust levers (there is symbology on the engine instruments which show you the position of the thrust levers and the actual EPR setting so that you can match them up before you disconnect the autothrust system). This provides a smooth transition between manual and autothrust use (no power surge). When the autothrust system failed on AF447, the thrust levers were in the CL detent. There is a difference if the system is turned off manually or due to a system failure. If the autothrust system is turned off manually using the pushbutton's on the thrust levers, the system will go to the max power setting of the CL detent unless the thrust levers are manually set as previously described. If there is a system failure the autothrust system goes into the "Thrust Lock Mode" and freezes the engine power at whatever thrust was being developed at the time of the failure. Thrust lock indications are a MASTER CAUT light, an amber flashing ENG THRUST LOCKED and AUTOFLT A/THR OFF,THR LEVERS.......MOVE ECAM messages, a single chime, and a STATUS page message. The chime is repeated every 5 seconds until pilot corrective action is taken. As you can imagine, when you have multiple failures, there's a lot of blinking lights, chimes, bells, whistles and other distractions not to mention a rather long list of ECAM and STATUS messages on the screens. The important thing to remember here is unless you reference the engine instruments, you don't know at what power setting the engines were actually producing at the time of the failure. The autothrust system on the Bus is OK, but remember the thrust levers never move so you lose one of the subtle cues normally found in the cockpit of most other aircraft. The autothrust system is normally very aggressive in trying to meet the speed demands placed on it. By this I mean you can get very large reductions or additions to thrust in order for the system to meet target speeds/mach settings. They are even more sensitive when turbulence is encountered and I've seen large variations in thrust setting in an attempt by the system to maintain target speeds. If you’ve ever ridden in the back of the A-330 in turbulence you will definitely notice the power changes. You also have to remember that power changes at max operating altitudes are very sluggish and it takes time to regain the target speed especially if the speed is bouncing around rapidly. In the AF447 situation, the PF (pilot Flying) slowed the aircraft from .82 to .80 mach. During this time he also encountered increasing turbulence and within a minute or so lost his instrumentation, autopilot, and autothrust. Until BEA releases the Flight Data Recorder readings and we know at what thrust setting the thrust lock mode froze the power, we won't know to what extent the autothrust system was responsible for possibly contributing to this accident. I hope this gives you a better understanding of how the system is supposed to work.

JJFFC:
Is it your position that the airspeed indicators did NOT react to ice on the pitot tubes?
I play golf as well, and still use my 3 iron. The 1 and 2 iron have been retired.

Yes, one needs practice to stay proficient.

Pitot tubes reacted to stall rather than to ice after AP disconnected
 

It is my opinion that after the plane had stalled, the pitot tubes didn't reacted to ice but to the stall and to the fact that the plane was really below 60 and inclined.

Maybe the AC disconnected because the Pitot tubes iced, but the BEA has never written this in this report : nobody knows why the AC disconnected.

Maybe the PF wanted to climb because of the weather (somebody already mentioned that in this topic).

The plot unthickens.....
If there is any shred of truth in the above posts - i.e. filing for LFBO but intending LFPG (all above board and as per regs, one assumes) - then a marginal fuel mentality scenario for lack of adequate CB avoidance cannot be dismissed. I checked the BEA report again for RTOW vs MTOW.... ah, suddenly it starts to make sense. I still maintain pts 1 to 11 on p49 for what happened subsequently. Whatever law it was in, the scenariio holds. Commercial pressure vs airmanship leading up to it? We shall one day see....

If you look at the findings of crash AF358 a lack of training, missing procedures and improper judgement seem to be the case. Of course this was a different situation than AF447 but it might indicate a not perfect safety culture and lack of or improper training within the airline.

]Conclusions (Wikipedia) AF358
The TSB concluded in their final report that the pilots had missed cues that would have prompted them to review their decision to land.[33] In their report[14] the TSB cited that
Air France had no procedures related to distance required from thunderstorms during approaches and landings
After the autopilot had been disengaged, the pilot flying increased engine thrust in reaction to a decrease in airspeed and a perception that the aircraft was sinking (spatial disorientation). The power increase contributed to an increase in aircraft energy and the aircraft deviated above the flight path.
At 300*feet above ground level, the wind changed from a headwind to a tailwind.
While approaching the threshold, the aircraft entered an intense downpour and the forward visibility became severely reduced.
When the aircraft was near the threshold, the crew members committed to the landing and believed their go-around option no longer existed.
The pilot not flying did not make the standard callouts concerning the spoilers and thrust reversers during the landing roll. This contributed to the delay in the pilot flying selecting the thrust reversers.
There were no landing distances indicated on the operational flight plan for a contaminated runway condition at the Toronto / Lester B. Pearson International Airport.
The crew did not calculate the landing distance required for runway 24L despite aviation routine weather reports (METARs) calling for thunderstorms. The crew were not aware of the margin of error.
The topography at the end of the runway beyond the area and the end of Runway 24L contributed to aircraft damage and injuries to crew and passengers.