ASN Wikibase Occurrence # 213551
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| Date: | Wednesday 18 July 2018 |
| Time: | 23:34 LT |
| Type: |  Airbus A330-323 |
| Owner/operator: | Malaysia Airlines |
| Registration: | 9M-MTK |
| MSN: | 1388 |
| Year of manufacture: | 2013 |
| Engine model: | Pratt & Whitney PW4168A |
| Fatalities: | Fatalities: 0 / Occupants: 229 |
| Aircraft damage: | Minor |
| Category: | Serious incident |
| Location: | Brisbane International Airport, QLD (BNE/YBBN) -
 Australia
|
| Phase: | Take off |
| Nature: | Passenger - Scheduled |
| Departure airport: | Brisbane International Airport, QLD (BNE/YBBN) |
| Kuala Lumpur International Airport (KUL/WMKK) | |
| Investigating agency: | ATSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
Malaysia Airlines flight MH134, an Airbus A330-300, took off from Brisbane Airport, Australia with no airspeed information.
The aircraft had landed at Brisbane Airport at 20:11 local time, after a flight from Kuala Lumpur, Malaysia.
In accordance with a local informal procedure and recommended practice, a support engineer placed covers on the aircraft’s three pitot probes (airspeed sensors) to prevent them from becoming blocked by wasp nests (a particular hazard at Brisbane Airport). The operator’s certifying engineer, who was primarily responsible for the aircraft’s airworthiness, did not initially know about the covers due to a miscommunication with the support engineer who had fitted them.
As the aircraft was being prepared for the return leg back to Kuala Lumpur, the flight crew, engineers, and dispatch coordinator were required to conduct various pre-departure checks, meant to identify aircraft damage or other unsafe conditions such as the fitment of pitot probe covers. However, these checks were omitted entirely or only partially completed, for a variety of reasons including inadequate communication and reduced diligence.
The certifying engineer saw the covers early in the turnaround but later forgot about them, and there was ambiguity around the division of responsibilities with regard to the final walk-around portion of the transit check. The support engineer who had fitted the pitot covers left to work on another aircraft and was unable to return before the occurrence aircraft was dispatched.
As a result the three pitot covers were not removed.
With the aircraft ready for departure, pushback commenced at 23:18. At 23:24, the flight crew commenced taxi for a take-off on runway 01. The wind was calm and there was no cloud.
The first officer was the pilot flying (PF) and the captain was the pilot monitoring (PM).
At 23:31 the flight began the takeoff roll on runway 01. When the aircraft accelerated through a groundspeed of 50 kts red speed (SPD) flags appeared on both primary flight displays (PFD).
The pilots made several remarks regarding the airspeed as the aircraft accelerated past 100 kts.
The first officer reported that they commenced rotation by judging the aircraft’s position on the runway, which happened to be at exactly VR. Passing about 120 ft the undercarriage was retracted.
After take-off, the PFDs probably both displayed mostly a speed flag and sometimes an erroneously very low airspeed. The integrated standby instrument system (ISIS) displayed speed at or near the bottom of the speed scale (30 kt) throughout the take-off and less than 60 kt for the remainder of the flight.
The flight crew carried out actions for unreliable airspeed indications and made a PAN call to air traffic control (ATC) at 23:33, advising they had unreliable airspeed indications.
The flight crew continued to climb above 10,000 ft and manoeuvred the aircraft to the north-east of Brisbane Airport where they carried out several checklists, troubleshooting and preparation for an approach and landing on runway 01 .
In accordance with published procedures, the flight crew turned off the three air data reference systems (ADRs) at 23:43. This activated the aircraft’s backup speed scale (BUSS), which provided a colour-coded speed scale derived from angle of attack and other information, and altitude derived from GPS data. The flight crew also obtained groundspeed information from ATC, and used the aircraft’s radar altimeter.
Normal landing gear extension could not be accomplished with all three ADRs off. The flight crew performed a landing gear gravity extension before conducting an overweight landing on runway 01 at 00:33.
After landing the flight crew stopped the aircraft on the runway as nose wheel steering was unavailable following a landing gear gravity extension. The main landing gear doors, which remain open following a gravity extension, had minor damage where they contacted the runway surface. The aircraft was towed to the gate where the passengers and crew disembarked. There were no reported injuries during the flight.
Contributing factors
- In the absence of clear instruction or guidance, the Aircraft Maintenance Services Australia support engineer fitted pitot probe covers to the aircraft shortly after its arrival, as was done for some other airlines to mitigate the threat of wasp infestation. Later, the engineer left to perform tasks on another aircraft and did not return to the aircraft prior to its departure as intended.
- Due to miscommunication or error, a technical log entry was not made following the fitment of pitot probe covers. As a result, when the technical log was reviewed prior to flight, the presence of pitot probe covers was not detected.
- The Malaysia Airlines engineer saw the pitot probe covers fitted to the probes during the transit check, about 2 hours before departure, and intended to ask the support engineer to remove them. However, associated with the limitations of prospective memory, the operator’s engineer subsequently did not remember to do so.
- The captain did not expect, or detect, the presence of the pitot probe covers during their pre-flight exterior inspection (walk-around). The captain did not include a number of the required check items, including the right side pitot probe, and looked at the left side pitot probe area briefly.
- The Malaysia Airlines engineer did not perform a final walk-around inspection of the aircraft, including a check for pitot probe covers, as required by the transit check that the engineer had certified as complete. The engineer assumed that the walk-around would be completed by the support engineer and/or ground handlers.
- The Menzies Aviation person assigned as dispatch coordinator for the aircraft handed over that duty to another person immediately before pushback, and neither person conducted the required dispatch walk-around. This was the last procedural opportunity to identify the presence of pitot probe covers before the flight.
- The aircraft was released for flight with covers fitted to all three pitot probes, preventing the air data systems from measuring airspeed.
- There was limited and ineffective communication between the captain and first officer in response to the speed flag on each of the primary flight displays (which appeared at about 50 kt groundspeed during the take-off). This significantly reduced their coordination and capacity to interpret the situation with the limited time available.
- While independently trying to diagnose a rare and unfamiliar problem during take-off, the flight crew experienced high cognitive workload, time pressure, and stress. This reduced their capacity to effectively interpret the situation and make a decision early enough to safely reject the take-off.
- The Airbus guidance provided in the flight crew techniques manual and other manuals for assisting A330 flight crews to decide whether to continue or reject a take-off did not discuss unreliable airspeed indication scenarios. (Safety issue)
- In the Airbus A330, there was no auditory alert associated with nil or unreliable airspeed from two or more sources during take-off (a high workload, critical phase of flight). Comparatively, other critical failures provide both visual and auditory indications. (Safety issue)
- Although suitable for use in most situations, the streamers attached to the pitot probe covers supplied and used for A330 operations by Aircraft Maintenance Services Australia provided limited conspicuity due to their overall length, position above eye height, and limited movement in wind. This reduced the likelihood of incidental detection of the covers, which is important during turnarounds. (Safety issue)
- Some Aircraft Maintenance Services Australia (AMSA) engineers extended the use of pitot probe covers (to mitigate the threat of wasp infestation) to operators that did not explicitly require it, including Malaysia Airlines. This increased the likelihood of error associated with the use of pitot probe covers because AMSA engineers were not controlling the engineering activities and were not permitted to make technical log entries. (Safety issue)
- Aircraft Maintenance Services Australia did not have a reliable method to account for tooling and equipment (such as pitot probe covers) prior to aircraft dispatch when providing non-certifying engineering support. (Safety issue)
- Menzies Aviation staff did not consistently carry out the required arrival and pre-departure aircraft checks of Malaysia Airlines aircraft, and Menzies Aviation audit processes were not effective at evaluating compliance with these requirements. (Safety issue)
- Malaysia Airlines flight crew and engineers did not fully complete the required aircraft inspections. (Safety issue)
- Malaysia Airlines did not clearly specify the division of engineering responsibilities between Malaysia Airlines and Aircraft Maintenance Services Australia engineers at Brisbane, leading to ambiguity with regard to who should conduct the final walk-around portion of the transit check. This risk was increased by the operator commencing and continuing flights to Brisbane with interim ground handling and engineering arrangements that varied from usual industry practice. (Safety issue)
- Malaysia Airlines did not develop and disseminate guidance and procedures about the use of pitot probe covers to flight crews and engineers, and there was limited awareness among those groups of the need for pitot probe covers at Brisbane Airport. (Safety issue)
- The Malaysia Airlines risk assessment for the recommencement of operations into Brisbane had numerous errors and omissions that potentially reduced its effectiveness.
- Although Malaysia Airlines identified the potential risk of pitot probe obstruction by wasps at Brisbane, and decided to address the risk with the use of pitot probe covers, it did not effectively communicate risks and required actions between departments and follow them through to completion.
- Malaysia Airlines’ processes for the management of change did not follow recommended industry practices, and its risk and change management processes were not detailed and clear enough to assure:
* the appropriate level of involvement of subject matter expertise and safety groups
* that risk controls were implemented and monitored. (Safety issue)
Accident investigation:
 |
|
Sources:
https://www.atsb.gov.au/publications/investigation_reports/2018/aair/ao-2018-053/
https://www.flightradar24.com/data/aircraft/9m-mtk#1d2c6054
https://www.pprune.org/rumours-news/611306-mas-a330-bne-leaves-pitot-covers-2.html
Previous incident at Brisbane:
https://news.aviation-safety.net/2016/05/06/wasp-nest-blocks-a330-pitot-tube-emergency-landing-at-brisbane/
Images:
Aircraft about to be pushed back with pitot covers in place (two of three visible)
Media:
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 21-Jul-2018 09:42 | harro | Added |
| 21-Jul-2018 10:08 | harro | Updated [Operator, Source, Narrative] |
| 21-Jul-2018 10:41 | harro | Updated [Embed code, Narrative] |
| 21-Jul-2018 10:46 | harro | Updated [Embed code, Narrative] |
| 30-Aug-2018 07:23 | harro | Updated [Embed code, Damage, Narrative, Photo] |
| 16-Mar-2022 14:24 | harro | Updated [Narrative] |
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