What Measures Have Been Taken to Avoid Air France 447 From Occuring Again

Eddie sez:

This crash would not accept happened with a more experienced set of pilots, no doubt about it. But that isn't to say we need to blame the pilots here. They were, in many ways, ordinary pilots. And therein lies the problem.

"To put it briefly, automation has made it more and more unlikely that ordinary airline pilots will ever have to face up a raw crisis in flying—but besides more than and more unlikely that they will be able to cope with such a crisis if one arises."

— William Langewiesche

But I don't concur that this situation is without a solution.

The days of pilots who are well schooled at dealing with all manner of things going wrong are coming to an end. That generation of pilots has long ago started retiring and pretty soon they volition all be footnotes in history. You cannot train this kind of thing in a simulator, where the absent risk of real injury are expiry cannot be simulated. But we can, I recollect, train pilots to realize when things are not equally they should be, and how to render a situation uncertain into a situation recognizable.

I recollect we should all have a "bag of tricks" to detect when things are non equally they should exist and a way to make things sane again. I will hint at them here, just I outline this bag of tricks in greater detail here: That Looks About Right (TLAR).

A lot has been made of Airbus issues with keeping control from the pilot ("Normal Police") except in highly rare circumstances ("Alternate Law"), and this kind of matter would never happen in a Boeing. In fact, something similar has happened in a Boeing. See: Aero Republic of peru 603. It is certainly more likely in an Airbus, but those of us who haven't gone to the Nighttime Side need to have the aforementioned pocketbook of tricks. If you aren't familiar with Airbus Control Laws, this case study may not make any sense. For a primer, see Airbus Control Laws.

Everything hither is from the references shown beneath, with a few comments in an alternate color.

Photo: PFD in Normal Police force, BEA Report, figure 6.
Click photo for a larger prototype

Last revision:

20180615

Cover Story:

20180701

Accident Written report

• Date: 1 June 2009
• Time: 0014
• Type: Airbus A330-203
• Operator: Air French republic
• Registration: F-GZCP
• Fatalities: 12 of 12 crew, 228 of 228 passengers
• Aircraft fate: Destroyed
• Stage: En route
• Airport (departure): Rio de Janeiro-Galeao International Drome, Brazil (SBGL)
• Airdrome (arrival): Paris-Charles de Gaulle Airport (LFPG)

Narrative

This was a 3 airplane pilot crew with a helm and 2 copilots. The airplane pilot flying was an "ab initio" Air France hire, he started his airline career three years after earning his first pilot'southward license, and six years afterward, found himself flying this Airbus over the Atlantic, unprepared for dealing with what should have been a elementary problem.

The captain was also inexperienced, merely would probably have dealt with the problem improve had he been in the seat. The rules for these long duration flights permit this kind of thing — the captain leaves the seats for hours at a time, leaving two lesser experienced copilots in control.

Finally, the design of the airplane plays a big function in this blow. Had the flight director provided more intuitive guidance when faced with an absence of pitot data coupled with improper airplane pilot inputs, either airplane pilot in the seat or the captain from the aisle could have more quickly figured out what the problem was. Had the two control sticks been somehow linked and so that one airplane pilot understood the other airplane pilot had reverse inputs, the pilots could take figured out why the plane's operation was contrary to their inputs. And the use of "normal" and "alternate" command laws themselves may take played a factor. The pilots were taught that the airplane cannot stall under normal law. They spend all of their flight fourth dimension in normal law. When they notice themselves in alternating constabulary, it is understandable that their minds would still exist in the "we can't stall" mentality.

Photograph: PFD in Alternate 2 Law, BEA Report, figure 7.
Click photo for a larger image

[BEA Report, ¶1.1]

• On Sun 31 May 2009, the Airbus A330-203 registered F-GZCP operated by Air France was programmed to perform scheduled flight AF 447 between Rio de Janeiro Galeão and Paris Charles de Gaulle. Twelve crew members (3 flight coiffure, nine cabin coiffure) and 216 passengers were on board. The departure was planned for 22 h 00.
• At around 22 h ten, the crew was cleared to kickoff up engines and exit the stand. Takeoff took place at 22 h 29. The Captain was Pilot Not Flying (PNF); ane of the copilots was Pilot Flying (PF).
• At the start of the Cockpit Vocalisation Recorder (CVR) recording, shortly after midnight, the airplane was in cruise at flight level 350. Autopilot 2 and auto-thrust were engaged. Auto fuel transfer in the "trim tank" was carried out during the climb. The flight was calm.
• At one h 35, the aeroplane arrived at INTOL betoken and the crew left the Recife frequency to change to HF communication with the Atlántico Oceanic control heart. A SELCAL test was successfully carried out, only attempts to found an ADS-C connection with DAKAR Oceanic failed.
• Soon later, the co-pilot modified the scale on his Navigation Display (ND) from 320 NM to 160 NM and noted ". . . a thing directly alee". The Captain confirmed and the crew again discussed the fact that the high temperature meant that they could non climb to flight level 370.
• At 1 h 45, the aeroplane entered a slightly turbulent zone, just before SALPU point. Note: At near 0 h 30 the crew had received information from the OCC about the presence of a convective zone linked to the inter-tropical convergence zone (ITCZ) between SALPU and TASIL.
• The coiffure dimmed the lighting in the cockpit and switched on the lights "to meet". The co-pilot noted that they were "inbound the cloud layer" and that it would take been good to be able to climb. A few minutes later, the turbulence increased slightly in strength.
• Shortly after 1 h 52, the turbulence stopped. The co-pilot again drew the Captain'south attention to the REC MAX value, which had then reached flying level (FL) 375. A brusk fourth dimension later, the Captain woke the second co-pilot and said "[…] he'southward going to take my place".
• At around 2 h 00, after leaving his seat, the Helm attended the briefing between the 2 co-pilots, during which the PF (seated on the right) said specifically that "well the trivial bit of turbulence that you but saw nosotros should find the same ahead nosotros're in the cloud layer unfortunately we can't climb much for the moment considering the temperature is falling more slowly than forecast" and that "the logon with DAKAR failed". And then the Captain left the cockpit.
• The aeroplane approached the ORARO signal. Information technology was flying at flying level 350 and at Mach 0.82. The pitch attitude was nearly ii.5 degrees. The weight and residue of the aeroplane were around 205 tonnes and 29%.
• The two copilots once again discussed the temperature and the REC MAX. The turbulence increased slightly. At ii h 06, the PF called the cabin crew, telling them that "in ii minutes we ought to be in an area where it volition start moving about a chip more than than now you'll accept to watch out there" and he added "I'll telephone call you when we're out of it".
• At effectually ii h 08, the PNF proposed "go to the left a bit [. . . ]". The HDG mode was activated and the selected heading decreased past about 12 degrees in relation to the route. The PNF changed the gain aligning on his weather condition radar to maximum, after noticing that it was in calibrated mode. The crew decided to reduce the speed to about Mach 0.8 and engine de-icing was turned on.
• At ii h x min 05, the autopilot then the motorcar-thrust disconnected and the PF said "I accept the controls". The aeroplane began to roll to the right and the PF made a nose-up and left input. The stall warning triggered briefly twice in a row. The recorded parameters showed a abrupt fall from almost 275 kt to 60 kt in the speed displayed on the left chief flight display (PFD), then a few moments later on in the speed displayed on the integrated standby musical instrument system (ISIS). The flight control law reconfigured from normal to alternate. The Flying Directors (FD) were not disconnected by the crew, but the crossbars disappeared.
• Note: Just the speeds displayed on the left side and on the ISIS are recorded on the FDR; the speed displayed on the right side is not recorded.
• At two h ten min 16, the PNF said "we've lost the speeds" then "alternate law protections". The PF made rapid and loftier amplitude roll control inputs, more than or less from terminate to stop. He also made a nose-up input that increased the aeroplane's pitch attitude up to 11° in ten seconds.
• Between 2 h 10 min xviii and 2 h ten min 25, the PNF read out the ECAM messages in a disorganized fashion. He mentioned the loss of autothrust and the reconfiguration to alternate law. The thrust lock function was de-activated. The PNF chosen out and turned on the wing anti-icing.
• The PNF said that the aeroplane was climbing and asked the PF several times to descend. The latter then made several nose-down inputs that resulted in a reduction in the pitch mental attitude and the vertical speed. The aeroplane was then at virtually 37,000 ft and continued to climb.
• At about 2 h 10 min 36, the speed displayed on the left side became valid again and was then 223 kt; the ISIS speed was still erroneous. The plane had lost almost 50 kt since the autopilot disconnection and the get-go of the climb. The speed displayed on the left side was wrong for 29 seconds.
• At 2 h 10 min 47, the thrust controls were pulled back slightly to 2/three of the IDLE/CLB notch (85% of N1). Two seconds later, the pitch attitude came dorsum to a little above half-dozen°, the roll was controlled and the angle of attack was slightly less than v°.

The AOA is not displayed in this cockpit.

• The plane's pitch mental attitude increased progressively beyond 10 degrees and the plane started to climb.
• From 2 h x min 50, the PNF chosen the Captain several times.
• At two h 10 min 51, the stall alert triggered over again, in a continuous manner. The thrust levers were positioned in the TO/GA detent and the PF fabricated nose-upwardly inputs. The recorded bending of attack, of around 6 degrees at the triggering of the stall alarm, continued to increment. The trimmable horizontal stabilizer (THS) began a olfactory organ-up movement and moved from 3 to 13 degrees pitch-up in about ane minute and remained in the latter position until the terminate of the flight. Around fifteen seconds later, the ADR3 existence selected on the right side PFD, the speed on the PF side became valid again at the same time as that displayed on the ISIS. Information technology was then at 185kt and the iii displayed airspeeds were consistent. The PF continued to make nose-up inputs. The aeroplane's altitude reached its maximum of about 38,000 ft; its pitch attitude and bending of attack were 16 degrees.
• At 2 h 11 min 37, the PNF said "controls to the left", took over priority without whatever callout and connected to handle the plane. The PF nearly immediately took back priority without any callout and continued piloting.

The control sticks on each side do not provide whatsoever tactile feedback from the reverse side. In this case, the PNF pushing nose down would be unnoticed by the PF, and the PF pulling olfactory organ up would be unnoticed by the PNF.

• At effectually 2 h 11 min 42, the Captain re-entered the cockpit. During the post-obit seconds, all of the recorded speeds became invalid and the stall alert stopped, after having sounded continuously for 54 seconds. The altitude was then nearly 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was most -10,000 ft/min. The plane'due south pitch attitude did not exceed xv degrees and the engines' N1's were shut to 100%. The aeroplane was bailiwick to scroll oscillations to the correct that sometimes reached forty degrees. The PF fabricated an input on the side-stick to the left stop and nose-upwards, which lasted about thirty seconds.
• At 2 h 12 min 02, the PF said, "I have no more than displays", and the PNF "nosotros accept no valid indications". At that moment, the thrust levers were in the IDLE detent and the engines' N1's were at 55%. Around fifteen seconds later, the PF made pitch-downward inputs. In the post-obit moments, the angle of assault decreased, the speeds became valid again and the stall warning triggered once more.
• At 2 h 13 min 32, the PF said, "[we're going to go far] at level ane hundred". About fifteen seconds later, simultaneous inputs by both pilots on the side-sticks were recorded and the PF said, "go ahead you have the controls".
• The angle of attack, when it was valid, always remained above 35 degrees.
• From 2 h 14 min 17, the Footing Proximity Warning System (GPWS) "sink rate" so "pull up" warnings sounded.
• The recordings stopped at two h 14 min 28. The last recorded values were a vertical speed of -10,912 ft/min, a basis speed of 107 kt, pitch mental attitude of 16.2 degrees nose-upward, roll angle of 5.three degrees left and a magnetic heading of 270 degrees.
• No emergency message was transmitted by the crew. The wreckage was institute at a depth of 3,900 metres on 2 April 2011 at most half dozen.v NM on the radial 019 from the terminal position transmitted by the aeroplane.

Analysis

The copilot in the correct seat (the pilot flying) seemed to accept been preoccupied with the idea they needed to climb to avoid the conditions causing their turbulence. When pitot icing acquired all three sources of pitot information to exist momentarily lost, the autopilot clicked off and he found himself hand-flying a big aircraft at high altitude, for peradventure the first time. Well-nigh shipping do non handle well at high altitude, and a heavy aircraft is fifty-fifty less responsive. Control inputs need to be minor, shine, and deliberate. This airplane pilot's inputs were large, abrupt, and erratic. Had he done nothing at all, the airspeed data would accept returned and the autopilot could accept been reengaged. It appears all he needed to do was maintain attitude for 1 minute. But it only took a minute to depart controlled flight.

Pilots

• Captain

[Extracted from BEA Report, ¶1.5] The captain was 58 years old with well-nigh xi,000 hours total time, over vi,000 hours equally helm, and 1,747 in type, all as captain. He started with Air French republic as a flight attendant, earned several ratings as a not-airline pilot, mostly in light shipping. He was hired past Air Inter airline in a Caravelle and so A300. He became Picture qualified for the get-go time in 1997, two days before Air France and Air Inter merged. A twelvemonth later he became a captain with Air France on the Boeing 737-200. Three years afterward exist became A320 rated. 3 years after that he added an A330 rating, a year after that he failed a line training flight test. (This is his offset failure noted in the accident written report.) . He added at A340 rating in 2007.

[Langewiesche] The coiffure arrived in Rio three days earlier the accident and stayed at the Sofitel hotel on Copacabana Embankment. At Air France, the layover there was considered to exist peculiarly desirable. [The] captain, Marc Dubois, 58, was traveling with an off-duty flying attendant and opera singer. In the French manner, the blow study made no mention of Dubois's private life, merely that omission and so required a finding that fatigue played no role, when the captain's inattention conspicuously did. Dubois had come the difficult manner, flying many kinds of airplanes earlier hiring on with Air Inter, a domestic airline subsequently absorbed by Air French republic; he was a veteran pilot, with most eleven,000 flying hours, more half of them as helm. But, information technology became known, he had gotten merely one hour of sleep the previous night. Rather than resting, he had spent the solar day touring Rio with his companion.

• Copilot in the left seat

[Extracted from BEA Written report, ¶one.5] The copilot in the left seat was 37 years one-time with effectually vii,000 hours total fourth dimension, almost 5,000 of that in blazon. He appears to have been an "ab initio" trainee hired directly by Air France simply six years after earning his base of operations license. He went directly into the A320 with Air France and later added at A340 and and so the A330 type ratings.

• Copilot in the correct seat

[Extracted from BEA Report, ¶1.v] The copilot in the correct seat was 32 years sometime with nearly iii,000 hours full time, 800 in type. Three years after earning his private airplane pilot's license, Air France hired him and a yr later he was flying the A320. 3 years after he added the A340 so the A330 ratings.

[Langewiesche] Occupying the correct seat was the inferior co-pilot, Pierre-Cédric Bonin, 32, who had brought along his married woman for the trip, leaving their two young sons at home. [ . . . ] Bonin, whose plow it was to be the Pilot Flying—making the takeoff and landing, and managing the automation in cruising flight. Bonin was a type known equally a Visitor Infant: he had been trained nearly from scratch by Air French republic and placed directly into Airbuses at a fourth dimension when he had only a few hundred flight hours nether his belt. By now he had accumulated two,936 hours, just they were of low quality, and his experience was minimal, considering almost all of his flight fourth dimension was in fly-by-wire Airbuses running on autopilot.

[BEA Report, ¶1.17.one.v.4] A Flight Safety report was made in 2006 by an airline internal committee post-obit incidents and accidents, in particular the Air France accident at Toronto in August 2005. The commission studied events at the airline that had occurred between 1985 and 2006. Notable elements from the written report identified:

• During the menses in question, two-thirds of the events occurred on long-haul flights;
• The "situational awareness", "controlling" and "crew synergy" causal factors were inseparable and constituted by far the most meaning contributing factor;
• Piloting abilities of long-booty and/or ab initio pilots are sometimes weak;
• A loss of mutual sense and general aeronautical cognition were highly noticeable;
• Weaknesses in terms of representation and awareness of the situation during organization failures (reality, seriousness, induced effects).

Speed Measurement

Photo: Speed Measurement System, (BEA, Figure 4)
Click photo for a larger image

[BEA Report, ¶1.half-dozen.half dozen] Information on the airspeed measuring system

• The speed is deduced from the measurement of two pressures:
• Total pressure (Pt), by means of an instrument called a Pitot probe;
• Static pressure level (Ps), by means of a static pressure sensor.
• The Airbus A330 has three Pitot probes and six static pressure sensors.
• These probes are fitted with drains allowing the removal of h2o, and with an electrical heating system designed to prevent them from icing upwardly.
• The pneumatic measurements are converted into electrical signals by eight ADM'south and delivered to the calculators in that form.
• The CAS and Mach number are the main items of speed data used by the pilots and the systems to command the aeroplane. These parameters are elaborated past iii computers, called ADIRU, each consisting of:
• An ADR module which calculates the aerodynamic parameters, specifically the CAS and the Mach;
• An IR module that provides the parameters delivered by the inertial units, such every bit ground speed and attitudes.
• There are therefore three speed data elaboration systems that function independently of each other. The probes known as "Helm" supply ADR ane, the "Kickoff Officer" probes supply ADR 2 and the "Standby" probes supply ADR three.
• The standby instruments elaborate their speed and distance information directly from the pneumatic inputs ("standby" probes), without this being processed by an ADM or ADR. The ISIS is a unique standby musical instrument integrating speed, distance and attitude information. It uses the same static and total pressure level sensors every bit ADR3.
• The autopilot, flight director and autothrust functions are ensured by two Flight Management Guidance and Envelope Computers (FMGEC), continued in particular to a Flight Control Unit of measurement (FCU). Each of these 2 computers can perform these three functions.
• In order to operate, and make up one's mind the FD'southward cues, the FMGEC need to use the data from at least two ADR'south and two IR's, which they must consider to be valid. The monitoring performed by the FMGEC on the ADR and IR parameters looks for deviations with respect to two other values. For instance, if 1 of the parameters from an ADR deviates excessively from the values indicated for the same parameter by the ii other ADR'south, so the first shall be considered every bit invalid and will non be used. If at least two ADR's or 2 IR's are invalid, the FMGEC can no longer make up one's mind the FD'southward cues and the crossbars disappear. However, the FD's are not disengaged; the corresponding lights on the FCU remain lit.

Ice Crystals

Photograph: Pitot probe diagram, BEA Written report, figure 8.
Click photo for a larger paradigm

[BEA Report, ¶1.6.ix.6]

• When highly specific climatic weather are met, in particular with the presence of ice crystals in excessive quantities, the weather for utilise of the probes can exceed the conditions for qualification and robustness. In this type of situation, a partial obstruction of the total pressure probes in icing conditions and at high altitude (above xxx,000 feet) tin can occur. This results in a temporary and reversible deterioration of full pressure measurement.
• In the presence of ice crystals, there is no visible accretion of ice or frost on the outside, nor on the nose of the probe, since the crystals bounce off of these surfaces. However, the ice crystals can be ingested by the probe air intake. Co-ordinate to the flight atmospheric condition (altitude, temperature, Mach) if the concentration of crystals is greater than the capacity for de-icing of the heating element and evacuation by the purge holes, the crystals accumulate in large numbers in the probe tube.
• As a result, a physical barrier is created inside the probe that volition disturb the measurement of full pressure, this then existence able to approach that of the measured static pressure.
• Every bit presently as the concentration of ice crystals is lower than the de-icing capacity of the probe, the physical barrier created by the accumulation of crystals disappears and measurement of the total pressure becomes right again.
• Experience and follow-upwards of these phenomena in very severe atmospheric condition show that this loss of office is of express elapsing, in general around one or 2 minutes.

AOA

Photo: Evolutions of recorded angles of attack and of the stall warning trigger threshold, BEA Report, figure 62.
Click photo for a larger image

[BEA Study, ¶i.xvi.3.2]

• From ii h 10 min 05 onwards, the flight control law was alternate and the stall warning triggered and stopped several times until the end of the flight. Only the values for ane Mach calculation were recorded, although the alarm triggering threshold depends on all three.
• The activations of the warning picked up by the CVR were identified every bit occurring at between two h 10 min 10.4 and 11.iii and between two h 10 min 13 and 13.iv. The brusk elapsing of activation did not brand it possible to find it from the "Stall warning" parameter, but the FWC 1's "Master warning" parameters were triggered on one bespeak at this time. Notwithstanding, this alert should accept continued until well-nigh two h 10 min 15.v, and then take been triggered once again between two h 10 min 17 and 19. The disabling of this alarm was probably due to the fact that, between thirteen.4 and xv.5 and so betwixt 17 and 19, and possibly at other times, the three Mach values were abnormally low (iii Pitot probes iced up). The warning triggering threshold then suddenly increased to values of near 10°, much greater than the recorded angles of attack, which led to the warning stopping.
• Analysis of the parameters showed that the stall alert stopped concomitant with the invalidity of the 3 angles of attack, and was triggered once again when at least one of them became valid again. In view of the farthermost values of angle of attack experienced by the aircraft, the change to the threshold equally a function of Mach was secondary.

Aircraft Behavior

[BEA Report, ¶1.16.iv.1]

• A simulation of the shipping behaviour was conducted based on the theoretical model and on the PF's inputs (sidestick and thrust). The validity of the model is express to the known flight envelope based on flight tests. Consequently, information technology was possible to acquit the simulation on the menses from 2 h 10 min 00 s to 2 h 10 min 54 s.
• The simulation demonstrated the following:
• From about 15 seconds before disconnection, the autopilot countered aerological disturbances whose intensity would be defined as "low-cal" on the ICAO calibration (variations in vertical acceleration of less than 0.five 1000);
• When the autopilot disengaged, a concomitant lateral gust acquired the shipping to depart from its flight path with a roll to the correct;
• The subsequent curl movements resulted from the inputs by the PF;
• The aircraft's movements in the longitudinal axis were primarily due to the inputs by the PF, with the exception of small variations due to the aerology (variations in normal dispatch of about 0.2 grand);
• The turbulence eased as from about ii h 10 min 30 s;
• With no PF inputs, the aircraft would accept gradually rolled further to the left but the variations in pitch attitude and altitude would have been pocket-size.

Airplane pilot Inputs

[BEA Report, ¶two.ane.2.three]

• When the autopilot asunder, the roll bending increased in two seconds from 0 to +8.4 degrees without any inputs on the sidesticks. The PF was immediately absorbed past dealing with scroll, whose oscillations tin can be explained by:
• A big initial input on the sidestick nether the upshot of surprise;
• The continuation of the oscillations, in the time it took to adapt his piloting at high altitude, while subject to an unusual flight police force in ringlet (direct constabulary).
• In addition, the deviation in roll may accept been caused by the chance of turbulence that had preoccupied the PF in the minutes leading up the autopilot disconnection.
• Post-obit the autopilot disconnection, the PF very quickly applied nose-up sidestick inputs. The PF's inputs may be classified as precipitous and excessive. The excessive amplitude of these inputs fabricated them unsuitable and incompatible with the recommended aeroplane handling practices for loftier altitude flight. This olfactory organ-up input may initially have been a response to the perception of the aeroplane'due south movements (in particular the reduction in pitch bending of two° associated with the variation in load cistron) just before the AP disconnection in turbulence. This response may have been associated with a desire to regain prowl level: the PF may have detected on his PFD the loss of altitude of about 300 ft and loss of vertical speed of the society of 600 ft/min in descent. The excessive nature of the PF's inputs can exist explained by the startle effect and the emotional shock at the autopilot disconnection, amplified by the lack of practical preparation for crews in flight at high distance, together with unusual flight control laws.
• Although the PF's initial excessive olfactory organ-upwards reaction may thus be fairly easily understood, the same is non true for the persistence of this input, which generated a significant vertical flying path deviation. The rubber investigation has made it possible to exclude, with reasonable certainly, the explanation that the repeated nose-up inputs were caused past the PF's unsuitable flying position (exam of the adjustment of his seat showed that it was adjusted in a way that was adapted to his morphology). Examination of the FDR parameters indicated that during the flying controls check undertaken while taxiing in Rio-de-Janeiro, the roll inputs did not induce a pitch component.
• Whether the PF's nose-up inputs were deliberate or not, there was no verbal expression of this to the PNF. At no time did the PF signal his intentions or objectives with respect to the command and stabilisation of the flight path. Although the PF's diverse roll inputs indicate his intention to keep the wings horizontal, it is not possible to determine what the PF'due south target was in the longitudinal axis.

Identification of the Situation

[BEA Report, ¶ii.1.2.4]

• Once the first actions in response to the perceived anomaly is executed (returning to transmission piloting following AP disconnection) and the flight path stabilisation ensured, the philosophy of both the manufacturer and the operator is for the crew to look for additional data necessary to understand the problem and take action.
• Identifying the loss of speed data could have prompted the crew to utilize the "IAS douteuse" emergency manoeuvre, if they had considered that the safe carry of the flight was "dangerously affected", this condition being generally associated with avoiding a standoff with the high ground or terrain. Training for this emergency manoeuvre in a flight stage at low distance may reinforce this estimation by crews. In addition, the study of events involving loss of speed indications in cruise tends to evidence that the emergency manoeuvre is never applied, and so much so that the failure to perform this manoeuvre is not specific to the crew of AF 447.
• Neither was the non-ECAM emergency procedure "Vol avec IAS douteuse/ADR Check Proc" called out. A call for this procedure must exist sufficiently practised for it to get an automated response to awareness of an airspeed indication bibelot, regardless of any demand to construct a more elaborate agreement of the problem.
• In the instance of the accident, the crew did not associate the loss of displayed speeds and the associated process.
• The disabling of the THRUST LOCK function by the PF indicates that he was searching for information. The PF may therefore have been overloaded by the combination of his immediate and natural attempts to understand the situation that was added to the already demanding task of treatment the aeroplane.

Crew Reactions

[BEA Report, ¶2.1.3.three] Reactions of the crew to the stall alert

• Iv seconds before the triggering of the STALL 2 warning, the flying director crossbars reappeared on the PFDs. The vertical mode engaged was V/S fashion with a target value of +ane,400 ft/min. The modes displayed on the FMA were never chosen out by the crew. The horizontal bar then indicated a slight olfactory organ-up social club compared with the aeroplane symbol. The PF'due south nose-up input caused the increase in the bending of attack and triggered the stall warning. At the instant when the STALL two warning was triggered, at 2 h x min 51, the aeroplane's pitch mental attitude was 7 degrees, and increasing. A few seconds later, buffet started.
• The crew never referred either to the stall alarm or the buffet that they had probable felt. This prompts the question of whether the two co-pilots were aware that the aeroplane was in a stall state of affairs. In fact the situation, with a high workload and multiple visual prompts, corresponds to a threshold in terms of being able to take into business relationship an unusual aural warning. In an aural surround that was already saturated by the C-chord warning, the possibility that the coiffure did not place the stall warning cannot be ruled out.
• Even if the PF's acceptance (or rejection) of a stall diagnosis was never verbalised, even though some of his actions could be considered to be consistent with those recommended in an approach to stall situation: setting the thrust levers to the TOGA detent, or his business with keeping the wings horizontal. On the other hand, in the absenteeism of airspeed data known to be reliable, it is possible that the PF thought that the aeroplane was in an overspeed situation,notably due to his interpretations of several clues:
• The aerodynamic noise,
• The buffeting, that he might have interpreted equally being due to high speed,
• The speed trend arrow on the PFD, which at that time indicated acceleration.
• Some of the PF'due south actions may be interpreted as indicative of a perception of a hazard or of a diagnosis of overspeed. Firstly, the PF reduced the thrust during the seconds preceding the activation of the STALL 2 warning and the onset of buffet. Secondly, 51 s after the triggering of this alert, the PF said "I have the impression nosotros have speed" and then moved the thrust levers to the IDLE detent. He reformulated his impression a few seconds after, combined with an try to extend the speedbrakes.
• The awarding of maximum thrust was probably the result of the perception of the stall warning. However, the PF may take assimilated the triggering of the warning as a consequence of the reduction in thrust, which he had applied four seconds earlier; he should then have practical full thrust to render to the earlier situation.
• A few seconds subsequently, the PF said "I'm in TOGA, right?". Either he was unsure whether or not he had fix the thrust controls to the TOGA detent, as he intended, or he did not understand why this action was ineffective in clearing the stall alarm. This second instance might therefore betoken that the PF had built an erroneous mental representation of the plane'southward flight model, and that he had hoped that he could resolve the situation by applying TOGA thrust at high distance and a pitch attitude of twelve degrees, a strategy similar to that recommended at low altitudes. The fruitless result of his actions possibly heightened his mistrust of the warning.
• Finally, although the PNF had called out the reconfiguration to alternate law when reading the ECAM, and even though the indicators of the loss of protection should have been displayed on the PFD (SPD LIM and an amber cross in roll and yaw), it is possible that the PF was not fully aware of this reconfiguration and of what information technology implied. He may therefore take embraced the common belief that the aeroplane could non stall, and in this context a stall alarm was inconsistent.
• The pitch mental attitude oscillations, in the seconds following the activation of the stall alert, reveal that the handling of the airplane was clearly very difficult and probably demanded the PF's full attention. During this phase, the airplane symbol on the PFD was close to, but on average slightly above, the flight manager horizontal bar.
• Moreover, the flying manager displays could have prompted him to control a positive pitch bending, of about 12.five°. This value appears in the stall warning procedure for the take-off stage. It is possible that, even though he did non call it out, the PF had recalled this memorised value and and so had clung to this reference without remembering that it was intended for a different flying stage. The conjunction of this remembered value and the flight director displays may accept constituted one of the few (and maybe even the only) points of consistency in his general incomprehension of the situation.

Note: The "Vol avec IAS douteuse" procedure recommends disabling the FD, to prevent it from presenting cues that could potentially exist irrelevant.

• When the Captain returned to the cockpit, the airplane was in a rapid descent, though at an distance shut to the cruise level information technology was at when he had left. Under these conditions, and non having experienced the consummate sequence of events, information technology was very difficult for the Captain to make a diagnosis. He would have needed to question the co-pilots about the sequence of events, an approach that was blocked by the urgency of the situation and the stress conveyed by the PNF's tone of voice.
• Subsequently, his interventions showed that he had also not identified the stall: the multiple starts and stops of the stall warning certainly contributed to brand his assay of the situation more confused. He then seemed to accept based himself on the pitch mental attitude and thrust parameters to analyse the flying path.

Cause

This BEA written report has all the facts, merely fails to use them to conspicuously delineate causes. In this situation, the best window into what actually happened and how to prevent recurrence is to look at the recommendations. In this example, these two from Section 4 of the report:

"Consequently, the BEA recommends: that EASA review the content of check and preparation programmes and brand mandatory, in particular, the setting upwards of specific and regular exercises defended to manual aircraft handling of approach to stall and stall recovery, including at loftier distance."

"Consequently, the BEA recommends: that EASA and the FAA evaluate the relevance of requiring the presence of an angle of attack indicator straight accessible to pilots on board aeroplanes."

[BEA Report, ¶3.2]

• The obstacle of the Pitot probes past ice crystals during cruise was a miracle that was known simply misunderstood past the aviation community at the time of the accident.
• The occurrence of the failure in the context of flying in cruise completely surprised the pilots of flying AF 447. The apparent difficulties with airplane handling at high altitude in turbulence led to excessive handling inputs in roll and a abrupt nose-up input by the PF.
• The crew, progressively becoming de-structured, likely never understood that it was faced with a "simple" loss of three sources of airspeed information.
• The airplane went into a sustained stall, signalled past the stall alarm and strong cafe. Despite these persistent symptoms, the coiffure never understood that they were stalling and consequently never practical a recovery manoeuvre.

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