Volo Air Asia QZ8501 (SUB-SIN): recuperate le scatole nere


Sembra che ci siano importanti novita' sulle cause del tragico incidente.



AirAsia crash: Faulty part 'major factor'


A faulty component was a "major factor" when an AirAsia plane crashed into the Java Sea last December, killing 162 people, Indonesian officials say.

The first major report into the crash found that actions by the crew in response to the malfunction also contributed to the disaster.
The Airbus A320-200, going from Surabaya to Singapore, was 40 minutes into the flight when contact was lost.
The report is the result of a year-long investigation.
Investigators had initially indicated that bad weather was a major factor in the crash.
But the new report has found that the soldering on a tiny electronic part in the system that controlled the rudder was cracked, causing it to send four warning signals to the pilots.
The crew tried to fix the problem by resetting the computer, but this disabled the autopilot. They then lost control of the plane.
The plane then entered "a prolonged stall condition that was beyond the capability of the flight crew to recover," said Indonesia's national transport safety committee.
Maintenance crews were aware of the problem as it had occurred 23 times in 2014, and resetting the system was one of several methods used previously to address it, the report said.
Malaysia-based AirAsia's Chief Executive Tony Fernandes thanked investigators on Twitter and added that "there is much to be learned here for AirAsia, the manufacturer and the aviation industry".
"We will not leave any stone unturned to make sure the industry learns from this tragic incident."
Families of the 162 people on board AirAsia flight QZ8501 have been waiting anxiously for the results of this investigation.
Indonesian investigators did not release their preliminary findings earlier this year, saying they were under no legal obligation to do so.
Covering the crash at the time, the working theory was that pilot error must have been a major contributor, or that bad weather was a factor.
But this report shows that it was actually the response of the crew to a chronically faulty component on the plane that caused the plane to crash and that bad weather had nothing to do with it.
AirAsia will now have many questions to answer about why the aircraft was not better maintained and why its pilots were not better prepared to handle these problems.
The plane's wreckage was found days after the crash at the bottom of the Java Sea near Borneo.
Most of the passengers were Indonesian, and others on board included a Frenchman, a Singaporean, a Malaysian, a Briton, and three South Koreans.
Only 106 bodies have been retrieved so far.
The crash capped a year of major air disasters including the disappearance of MH370 and the shooting of MH17- both flights operated by Malaysia Airlines.

http://www.bbc.co.uk/news/world-asia-34972263

Anche in maniera piu' dettagliata da avherald:
http://avherald.com/h?article=47f6abc7/0028&opt=0
 
Anche in maniera piu' dettagliata da avherald:
http://avherald.com/h?article=47f6abc7/0028&opt=0

Molto, ma molto triste. Sicuramente ci saranno lezioni da imparare, a diversi livelli.
Due cose che mi inquietano particolarmente:
- L'inconveniente che ha dato origine al tutto era avvenuto già 23 volte quell'anno, con frequenze sempre maggiori - è davvero possibile per un operatore non prendere nessuna contromisura a fronte di queste segnalazioni così ricorrenti?
- Credo che la logica dei sidestick Airbus (se nessuno dei due prende la priorità, i comandi vengono sommati algebricamente) in situazioni di difficoltà / di emergenza mostri qualche limite.
 
Alla fine la dinamica sembra ahime' molto simile ad Adam Air 574, precipitato sempre in Indonesia 8 anni fa.
Guasto ad un sistema di bordo, preesistente e mai risolto (in quel caso l'ISR).
Nel tentativo di risolvere il problema, agendo non secondo le procedure, l'autopilota si disattiva o comunque cambia la modalità di funzionamento.
L'aereo va fuori assetto e i piloti non se ne accorgono in tempo, Probabilmente distratti dal problema originale.
Alla fine non sono in grado di recuperare l'assetto e l'aereo precipita.

Manutenzione carente, addestramento insufficiente, crew management. Ancora in Indonesia...
 
Manutenzione carente, addestramento insufficiente, crew management. Ancora in Indonesia...

Non mi piacciono le generalizzazioni, ma un malfunzionamento pluri-segnalato che combinato al distacco dell'autopilota determina la caduta di un aereo è abbastanza inquietante.
 
Mai generalizzare, ma spesso le colpe sono nel "sistema" ed infatti l'intera flotta indonesiana ha avuto per anni il divieto operativo in EU ed ora sono ammessi con limitazioni, (air Asia Indonesia era ammessa) dopo riforme. Questo incidente penso porterà ad ulteriori approfondimenti, che ne pensate?
 
Non mi piacciono le generalizzazioni, ma un malfunzionamento pluri-segnalato che combinato al distacco dell'autopilota determina la caduta di un aereo è abbastanza inquietante.

E' importante segnalare come il malfunzionamento non ha generato nè il distacco dell'autopilota, nè l'upset
Questo è stato causato dall'errata applicazione di una procedura di reset
 
E' importante segnalare come il malfunzionamento non ha generato nè il distacco dell'autopilota, nè l'upset
Questo è stato causato dall'errata applicazione di una procedura di reset

Di male in peggio.

A leggerla da ignorante, mi sembra una tragedia causata da pasticcioni.
 
La sequenza è stata più o meno (dai findings):

6. When the aircraft was cruising, there were three master caution activationsassociated with Rudder Travel Limiter Units (RTLU) and the amber ECAMmessages “AUTO FLT RUD TRV LIM SYS” between 2301 and 2313:41 andthe pilots performed the ECAM actions and the system returned to functionnormally.
Nota: ECAM ACTIONS= FAC 1 off then on (con il pushbutton)

7. At 2315:36 UTC, the fourth master caution and triggered ECAM message“AUTO FLT RUD TRV LIM SYS”, the recorder did not record any ECAMactions.

9. At 2316:27 UTC, the fifth Master Caution illuminated which was triggered byFAC 1 FAULT followed by FDR signature of alteration of parameters ofcomponents controlled by FAC 1 such as RTLU 1, Windshear Detection 1 andRudder Travel Limiter Actuator 1. Twelve seconds later, the FAC 1 parameterback to ON and all fluctuating parameters stopped.

10. At 2316:44 UTC, the sixth Master Caution triggered by AUTO FLT FAC 1 + 2FAULT and followed by FDR signature of alteration of parameters ofcomponents controlled by FAC 2. The Auto Pilot (A/P) and the Auto-thrust(A/THR) disengaged, and the Flight control law reverted from Normal Law toAlternate Law. The rudder deflected 2° to the left.118

11. The fault on FACs was associated with an interruption of electrical power whichwas likely due to the FAC CB being reset. (Nots: CB = Circuit breakers)

12. At 2316:54 UTC the FAC 2 parameter was back to ON and all fluctuatingparameters stopped. The autopilot and auto thrust remained disengaged. Flightcontrol law remained in Alternate Law.

13. The FAC pushbutton on overhead panel was not reset to OFF then ON, as aresult the FAC functions remained unavailable and all equipment controlled byFAC did not operating.

14. The rudder deflected 2° resulting in a roll rate of 6 degrees/second to the left, andwithout pilot input for 9 seconds, resulting the aircraft rolling to the left uncommandedup to 54°.

17. After the right side-stick activated, the aircraft roll angle reduced to 9° left. Thisrapid right rolling movement might cause an excessive roll sensation to the right.The SIC may have experienced spatial disorientation and over-corrected byshifting the side stick to the left which caused the aircraft rolled back to the leftup to 50°

18. The initial SIC action on side stick input of up to 15.1° backward resulting inpitch attitude of 9° within 3 seconds (2316:55 UTC) and was beyond the normalangle to regain the pre-set altitude of 32,000 ft while the guidance from theFlight Director was still available.

19. The FDR recorded at 2317:15 UTC the aircraft pitch reached 24° up. The PICcommanded „pull down...pull down‟ however the FDR recorded the right sidestick backward input increased resulting in the AOA increased up to a maximumof 48° up. The Standard Call Out applicable during final approach and goaroundmentioned in SOP should be “PITCH, PITCH” if the pitch angle reaches10°. There were no standard call outs for flight phases outside the final approachand go-around.
(Nota: PULL DOWN = ?????????)

22. From 2317:29 UTC the PIC side stick input started to became active with nosedown pitch commands and then mostly at neutral while the SIC side stick inputwas mostly at maximum pitch up until the end of the recording.

30. Observation on the Airbus A320 QRH, in the chapter „Computer Reset‟ it isstated that: In flight, as a general rule, the crew must restrict computer resets tothose listed in the table. Before taking any action on other computers, the flightcrew must consider and fully understand the consequences. This statement waspotentially ambiguous to the readers and might be open for multipleinterpretations.

31. 35. The stall condition is classified as an emergency which required the PIC to takeover control. The CVR did not record any command by the PIC that they weretaking over control of the aircraft using the standard call out. The standard callout to take over control described in the operator SOP, is “I HAVE CONTROL”and responded by the other pilot transferring the control by call out “YOUHAVE CONTROL” or by activating the priority button for 40 seconds.

38. Since 2317:29 UTC, both left and right side stick input were continuously activeuntil the end of the recording. The input were different where the right sidestickwas pulled for most of this segment, the nose down (forward) pitching commandsof the left sidestick became ineffective because of

Maintenance
41. The maintenance records showed that there were 23 Rudder Travel Limiterproblems starting from January 2014 to 27 December 2014.
42. The Reliability Report November 2014 recorded 4 pilot reports regarding theRTLU problem.
43. On 19 December 2014, the repetitive RTLU problem was inserted to MR2. Aftercompleting the scheduled flight, the maintenance personnel performed AutoFlight System (AFS) and the MR2 was considered closed.
44. On 21 December to 27 December 2014, the MR1 recorded 2 pilot reports on 25December 2014 and on 27 December 2014 related to RTLU while the FDRrecorded at least 9 problems.
45. The operator maintenance management utilized AMOS to manage maintenanceactivities. The data was uploaded by the maintenance personnel in all linemaintenance stations. The information is collected from MR1, CabinMaintenance and Scheduled Inspection.
46. Maintenance data analysis related to RTLU problem was inadequate because itwas only based on the MR1 which are available in the AMOS, while otherinformation such as from the PFR was not utilized.
47. The existing maintenance data analysis led to unresolved repetitive faultsoccurring with shorter intervals.
48. Evaluation of the maintenance data showed that the maintenance actionfollowing the RTLU problems were mostly by resetting computer by eitherresetting the FAC push button and followed by AFS test or resetting theassociated CBs.

52. The company policy did not clearly state to record the PFR. This resulted in theline maintenance stations not being aware of occurrence of similar problems.The line maintenance stations might repeat similar actions. None of the issuesreported was identified as meeting the repetitive defect definition which wouldhave triggered maintenance actions under the CMM requirements.
53. The available maintenance data record and analysis unable to identify repetitivedefects and analyse their consequences.