Air France 447 - On topic only!

[AJ]

If all 3 speed indications are gone a reversion to back up speed ensues which allows you to fly angle of attack instead of speed.

Hi Dazz, are you referring to the BUSS? Was that fitted to the accident aircraft?

[Darren Howie]

To answer MCM's statements in a little more detail and how misguided they are.

Firstly engine failures..
In any aircraft particularly a jet you know you have had a failure before any indications or movement of thrust levers or thrust indications.
To say a Boeing pilot is more aware is ridiculous at best. He is saying we are sitting there waiting for a bell to go off to tell us an engine has failed.
Sorry but you can feel it fail in takeoff or cruise. The only time you may have less indications is on descent.
SO in short no pilot AIrbus or otherwise is waiting for any "message" other than that sensation from the eseat of your pants that something has gone wrong. And thats the same feeling ALL pilots use.
How many Boeing pilots fly the aircraft in the cruise without autothrust.

I dont know any..Boeing guys normally disco the autothrust for an approach to avoid the pitch up and down Boeing's give with power changes which make hand flying so much more difficult than an Airbus.
As for the cruise sorry but its way to much work for anyone.
To say a 767 driver sits up there for 8 hours with the autothrust off is just plain wrong.
Also to say that a Boeing guy is more aware is actually doubly wrong.
Anyone with any Airbus time will tell you without the visual cues of thrust levers moving etc you actually have to be MORE concious of what is going on not less with your engines.
Hence i can tell you i flew back from Darwin last night with an approx N1 of 81% most of the way home.
As i said before and what is pretty clear is that this wasnt an aircraft related accident but based on training, crew procedures etc.


That is why the knowledge in any aircraft of power settings which will immediately keep you safe when combined with a pitch setting is so important.

[Darren Howie]

Hi AJ
The aircraft was a 2006 build and the BUSS hit the line in late 05.
All new aircraft have it fitted as standard.
Whether they where trained to use it or not dont know.
However its the most simple system to use i've seen.
Green band on the speed scale use thrust to keep it in the green.
You have the option when running the unrel speed procedure to not use it if you dont want to and revert to pitch/thrust tables.
When we had EBA thru EBD retro fitted we just started using it as it was so straight forward to training etc it was so easy to use in comparison with trying to set power's and pitches for configuring etc.
Great system..its being retro fitted to all our 320's as we have had several speed outages..including one far worse than the scenario in AF447.

[Theoddkiwi]

Its hard to understand what they seemed to be trying to achieve with the high climb rate.

They seemed to have acknowledge the unreliable speed indications but, then they he seems to have tried to fly using those speeds.

They have climbed to 38000ft with no change in thrust setting and at quite a high rate and ultimately the mother of all stalls.

There seems to have been a window of opportunity at about 37500 when AOA had reduced to 4 degrees.

What gets me is why when the aircraft is telling them they were stalling they did not push the nose down.

I am afraid Air France and its pilot training are going to be put under a lot of pressure here in terms of finger pointing and blame game.
And it would seem the poor Captain arrived 1min and 40 seconds too late and the jet was probably unrecoverable by then
I am also afraid that the passengers were probably aware that things were not good with roll oscillations up to 40 degrees.

Another aspect is the mention of the Captain waking the second copilot, if he had been asleep. He had been awake for 15mins and perhaps may not have been fully alert. I know it takes me a good twenty minutes to get my head working if i have fallen into a deep sleep.

[Theoddkiwi]

How many Boeing pilots fly the aircraft in the cruise without autothrust.

I dont know any..Boeing guys normally disco the autothrust for an approach to avoid the pitch up and down Boeing's give with power changes which make hand flying so much more difficult than an Airbus.

Well as a LAME on Boeings i have MEL'ed the Auto-Throttle a number of times and the pilots quite happily take the aircraft, even on the longer sectors.
Additionally in the times i have flown jump seat i have been pleasantly surprised how much our pilots fly by hand with both column and throttle. Perhaps my airline sees the value in its pilots keeping their basic aircraft handling up to speed. I get the impression our pilots actually quite like handflying and do it regularly.

[Darren Howie]

Theo i think operating under an MEL with the autothrust U/S and what we are talking about(day to day ops)are two different things.
Having flown a 320 from Cairns to Melbourne nil autothrust i can assure you it is far from acceptable with continuous concentration required for the entire flight.
We ended up in turbulence and settled on cruising at .76 well below normal cruise speed so that if any temp change etc occurred we wouldnt overspeed.
There is a reason why its a C item..and your right pilots do like hand flying!!

[AVION1]

Somehow reminds me of the West Caribbean Airways Flight 708 crash in south america, it was an MD-80, they stalled the aircraft at 38,000 ft and crashed nose up ! the pilots were pulling the nose, instead of lowering it and gain control of the airplane.

[Evan]

Hi AJ
The aircraft was a 2006 build and the BUSS hit the line in late 05.
All new aircraft have it fitted as standard.
Whether they where trained to use it or not dont know.
However its the most simple system to use i've seen.
Green band on the speed scale use thrust to keep it in the green.
You have the option when running the unrel speed procedure to not use it if you dont want to and revert to pitch/thrust tables.
When we had EBA thru EBD retro fitted we just started using it as it was so straight forward to training etc it was so easy to use in comparison with trying to set power's and pitches for configuring etc.
Great system..its being retro fitted to all our 320's as we have had several speed outages..including one far worse than the scenario in AF447.

Hello Darren, good to have an Airbus pilot back with us.

I've been bringing up BUSS since the old thread, wondering why it wasn't in use on this a/c. This is what I learned (all is from reliable sources):

- F-GZCP entered service in 4/2005, prior to when you say BUSS hit the line. (source: BEA)
- BUSS is standard on the A380, and OPTIONAL on the A330/340 (source: AIrbus)
- Air France considered installing BUSS on its jets, but decided against it. Here is the article (from Air France corporate website):

Updated 19 May 2010
The "Backup Speed Scale" or BUSS is a tool which pilots use when speed indications cannot be used.
To use the BUSS, the crew must first disconnect the three ADRs (air data reference - anemometric stations). Once these have been disconnected, the crew can no longer use them during the flight.
With the BUSS system, speed is no longer calculated by the Pitot probes, but by the aircraft's incidence probes. The speed indication, which is less precise, is presented in the form of green, ambre and red stripes. In a high turbulence situation at high altitude, the speed indication given is very unstable and difficult to use.
On its A330s and A340s, Air France considered installing the BUSS system offered by Airbus and carried out tests on its flight simulators. These tests did not lead Air France to adopt this system.
This is because it has the incovenience of depriving the crew of anemometric data during the flight once the BUSS system is activated, whereas experience has shown that the loss of speed indication is generally for a short time only. Moreover, the system is difficult to use at high altitude.
This has been confirmed by Airbus which recommends in a FOT (Flight Operations Telex) dated 9 September 2009 not to use this system at an altitude higher than 250, i.e. 7,600 metres (25,000 feet).

[Spectator]

I've been bringing up BUSS since the old thread, wondering why it wasn't in use on this a/c. This is what I learned (all is from reliable sources):

Thanks Evan. I was pretty confident that AF447 did not have the BUSS. But didn't have the time to back myself up. Your research is extremely diligent.

[Fear_of_Flying]

Its hard to understand what they seemed to be trying to achieve with the high climb rate.

They seemed to have acknowledge the unreliable speed indications but, then they he seems to have tried to fly using those speeds.

They have climbed to 38000ft with no change in thrust setting and at quite a high rate and ultimately the mother of all stalls.

There seems to have been a window of opportunity at about 37500 when AOA had reduced to 4 degrees.

What gets me is why when the aircraft is telling them they were stalling they did not push the nose down.

I am afraid Air France and its pilot training are going to be put under a lot of pressure here in terms of finger pointing and blame game.

I hope, before they leave, one of our Airbus experts will explain WHY the pilot might have continued to climb as he did. That is the $10,000 (actually several million dollar) question. Unlike Colgan, which seems to have been a moment of panic and incorrect reaction, this seems to have been more of a "hmm, I wonder what I should be doing now?" response.

The airspeed sensors were out for less than a minute the note says.

In the intro to the note, the BEA explains that it is releasing the info to counter the reports. Well, where did those reports come from? And it does turn out that the reports were not far off base. If I had to sum up this info about a week ago without revealing my hand too much, I might have said something like "Airbus not to blame", or "Data points to Pilot Error."

[guamainiac]

The term "edging the jet higher" has me wondering.

Is it possible that he had elected, with the failures that he was encountering, found himself entering and area of lift?

Was the PF edging the plane upwards ... "it wasn't cold enough to ascend to that level" ... or was he electing not to fight the upward motion of a thermal?

Is there anything that indicated he was pulling back a bit or is it possible this was a "natural ascent" due to the turbulence?

[Fear_of_Flying]

The term "edging the jet higher" has me wondering.

Is it possible that he had elected, with the failures that he was encountering, found himself entering and area of lift?

Was the PF edging the plane upwards ... "it wasn't cold enough to ascend to that level" ... or was he electing not to fight the upward motion of a thermal?

Is there anything that indicated he was pulling back a bit or is it possible this was a "natural ascent" due to the turbulence?

"nose-up inputs"

[Evan]

Reading the latest report seems to bring up more questions than answers.

A few things stood out:

The level of turbulence increased slightly and the crew decided to reduce the speed to about Mach 0.8.

As, suspected, they were slowing for turbulence penetration just prior to the A/THR disconnect, so thrust lock would have frozen a power setting below the one (CL) indicated by the thrust levers.

The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS).

As best I can recall, an erroneously low reading would indicate a pitot obstruction rather than a drainage issue (can anyone confirm this). If so, would that favor ice crystal ingestion over ice accretion?

At 2 h 10 min 16, the PNF said "so, we’ve lost the speeds" then "alternate law […]".

The PNF had no trouble in identifying the UAS condition, so we can put that one to rest.

At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs.

This appears to be the first thrust lever input. From this point on, we know power setting matches thrust lever angle.

The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.

Is this the automatic pitch trim in action? A smoking gun?

Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less than one minute.

The reason the BUSS system is not ideal at cruise altitude. Still, the a/c would remain in Alternate Law and thus stall protections are not restored with airspeed data.

Note: When the measured speeds are below 60 kt, the measured angle of attack values are considered invalid and are not taken into account by the systems. When they are below 30 kt, the speed values themselves are considered invalid.

Thus the stall warnings cease. Is this a smoking gun? Did Airbus engineers not foresee a situation where UAS might be the cause of such low airspeed, where AoA data is still valid and very critical in maintaining stall warnings?

---

The pilots were obviously not well trained for this. They failed to perform the two basic memory items. I think they might also have ignored the stall warnings because they knew the airspeed was erroneously low and considered this the cause of false stall warnings. However, the QRH specifies that pilots are to RESPECT STALL WARNINGS and to ignore any ECAM message warning them of RISK OF UNDUE STALL WARNING.

I'm also wondering if the altimeters and VSI could have been affected. The FPV was lost during the sequence. The FDR has them at 40° AoA and -10,000 ft/min V/S, but only 15° pitch with 100% N1 thrust. How is that possible? Did they reduce thrust at FL380 to remain in the envelope and let it fall, and then firewall it as they were falling out? This is not explained in the briefing. Or is it possible that the pitch indications were erroneous, both on the PFD and on the FDR? And why did they subsequently bring thrust back to IDLE in a developed stall, when airspeed was obviously needed? Did the PF do this or the Capt?

The best I can make of this is that thrust lock, a bit of load factor and pitch input caused an initial stall warning and an excessive rate of climb. They momentarily recovered by reducing pitch but the thrust setting remained too low and the pitch trim raised the AoA once again. With the second stall warning they initially applied TOGA thrust and pitch in excess of 10° This resulted in an excessive rate of climb until they reached their maximum FL380. Then it would seem that to reduce the V/S, they reduced thrust too aggressively while not reducing pitch and stalled, and then returned thrust to TOGA after the stall had developed, too late to prevent it, and then reduced again to IDLE fearing overspeed at at high rate of descent (apparently unaware of their pitch or AoA). That's the best I can make of it.

I am not surprised to hear that the pilots did not do the memory items correctly. That seems to be what killed them. Obviously, there was an industrywide training deficiency on this issue, and perhaps a deficient set of procedures issued by Airbus. The threat was obviously underrated, since ice-related pitot failure is not supposed to be happening at FL350, based on conventional wisdom at the time, and doesn't seem to occur outside the ITCZ. But it had been happening and both Airbus and the operators were aware that a threat existed. Neither seem to have reacted properly with training and procedures.

But I can't accept that such an experienced crew would not be well versed on general stall avoidance and recovery procedure either. They must have been deprived of vital positional awareness beyond airspeed data to get into the mess described in the report.

Or perhaps we still have a lot more to learn about human factors. I hope we will see the FDR plots and get a CVR translation soon. There are too many new questions in my head.

[EconomyClass]

The more info, the more confusion. If autothrust came off, but speed increased, doesn't that logically mean the pilot had to cause the climb?

Other question I can't find the answer to is: Once the plane starts to fall, all efforts now become useless? The controls available for the pilots have no effect on what the plane does? It said over 3 minutes falling. Was that three minutes of using the controls that no longer were working?

[guamainiac]

FoF, yes, thanks what I meant was gingerly edging the nose to match the lift.

I'll stand corrected but if you lower the nose in lift (entering the core of a thermal), you can gain speed. I'm probably wrong but that may have happened if the eye was on the altimeter.

It also mentioned that it was too warm to maintain flight at the altitude they were approaching and that sounds like a thermally induced "coffin corner".