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A320, vicinity Abu Dhabi UAE, 2012
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|On 16 November 2012, Captain of an A320 positioning for approach to Abu Dhabi at night became incapacitated due to a stroke. The First Officer took over control and declared a MAYDAY to ATC. The subsequent approach and landing were uneventful but since the First Officer was not authorised to taxi the aircraft, it was towed to the gate for passenger disembarkation. The investigation found that the Captain had an undiagnosed medical condition which predisposed him towards the formation of blood clots in arteries and veins.|
| Actual or Potential
|Flight Conditions||Not Recorded|
|Type of Flight||Public Transport (Passenger)|
|Intended Destination||Abu Dhabi International Airport|
|Take off Commenced||Yes|
|ENR / APR|
|Location - Airport|
|Airport vicinity||Abu Dhabi International Airport|
|Tag(s)|| PIC less than 500 hours in Command on Type,|
Copilot less than 500 hours on Type
|Tag(s)|| Flight Crew Incapacitation,|
Pilot Medical Fitness
|Damage or injury||No|
|Causal Factor Group(s)|
On 16 November 2012, the Captain of an Airbus A320 (A6-EII) being operated by Etihad Airways on a scheduled international passenger flight from Kuwait to Abu Dhabi as ETD308 was being positioned for an ILS approach to runway 31L at destination when the First Officer observed that the Captain had suddenly become incapacitated. ATC was advised and a MAYDAY declared after which the subsequent approach and landing were uneventful. The aircraft had to be towed to the gate for passenger disembarkation because the First Officer was not authorised to taxi the aircraft.
It was a noted that the 44 year-old Captain had accumulated 12,297 flying hours including 4,930 in command of which 332 were in command on the A320. The 57 year-old First Officer had accumulated 13,069 flying hours of which 84 were on the A320. Both pilots had P2 only ratings on the A330 and A340.
It was established that the Captain had been acting as PF. While 7nm south of the destination airport and in receipt of radar headings from APP towards an ILS approach to runway 31L with the AP engaged, the Captain's speech tone changed and within 30 seconds he had become incoherent. A minute later, the First Officer observed that he was slumped in his seat, leaning to his left and "appeared to be making involuntary movements" whilst "gasping for breath and making unusual noises". Since the Captain was "unresponsive", the First Officer disengaged the AP and took over control of the aircraft. Initial difficulty was caused by the Captain's involuntary pressure on the right rudder pedal which "put the aircraft into a 10 degree sideslip" and resulted in lateral acceleration of up to 0.26g. However, after the bank angle had reached 21º, straight and level flight was recovered. ATC was advised of the situation, a MAYDAY was declared and the cabin manager was called to the flight deck to be appraised of the situation and assist in securing the Captain clear of the controls with his seat in the fully aft position. A second member of the cabin crew assisted in administering oxygen from a therapeutic set brought from the passenger cabin and made a cabin PA in Arabic and English to see if there was a doctor on board but there was no response. Both cabin crew stayed in the flight deck for landing in order to monitor the Captain's condition and continued restraint and to continue to administer therapeutic oxygen.
The First Officer then engaged both APs and ATC continued to provide vectors to the ILS in accordance with requests made by the First Officer. Once on the ILS LOC, the APP controller transferred the aircraft to TWR who were advised that once landed, the aircraft would be stopped on the active runway to await assistance as prevailing operator procedures did not permit the aircraft to be taxied from the right hand seat. The APs were disconnected at 850 feet agl and twelve minutes after the First Officer had taken over control, an uneventful landing was accomplished on runway 31L. The aircraft was brought to a halt on the runway to await towing, TWR transferred the aircraft to GND and the aircraft engines were shut down. A few minutes later while awaiting the arrival of the emergency services, it became apparent that the Captain "had partially regained consciousness and appeared to be responsive and communicative". About 30 minutes after the aircraft had landed "paramedics arrived at the aircraft and entered the flight deck in order to evaluate the captain’s condition" after which it was decided that he could remain on board while the aircraft was towed to the gate. On arrival there, the Captain was the first person to disembark and was taken to the hospital for further checks and observation.
Most of the investigation was concerned with establishing the cause of the Captain's incapacitation in the absence of any prior symptoms during the incident flight or any detection of risk through the routine processes used to establish pilots' medical fitness.
It was noted that the Captain had been "in an unconsciousness state for about twenty minutes". After regaining consciousness, the Captain had "asked questions that indicated that he could not remember what had happened to him". He thought that he had been asleep and wondered why he had not been woken up. At this time, the aircraft had already landed and the Captain offered to taxi the aircraft, but the First Officer "preferred" to await the requested tow. Following recovery from unconsciousness, the Captain "exhibited no abnormal indications, except headache and pain in the lower back, similar to muscular pain".
Medical investigations concluded that the Captain had Antiphospholipid Antibody Syndrome (APS) which had led to a stroke which had caused him to lose consciousness. It was noted that this syndrome is an autoimmune disorder in which cell damage causes small unwanted blood clots to form in the body's arteries and veins. It was noted that persons at risk of this disorder may be clinically predisposed to its onset without showing or being aware of any symptoms and that diagnosis of APS requires a history of health problems which can be related to the presence of the specific cell damage origin and can occur at any age. Statistics of US origin were found which indicated that "one third of strokes occurring in people under the age of 50 are due to APS".
The Captain's medical history was examined and it was found that two years prior to the investigated incident he had been diagnosed with hypertension and appropriate medication had been prescribed. During his licence renewal application four months prior to the incapacitation, he had declared his medical history of hypertension and that he had been prescribed medication to control the condition. However, this disclosure occurred 20 months after diagnosis and it was noted that when made, the disclosure had not triggered any further medical examinations. It was found that during the year following the incapacitation, the Captain had not suffered any further episodes, loss of consciousness or seizure and continuous monitoring of his propensity to suffer blood clotting had indicated that his condition was stable.
The investigation noted the publication of two studies which had examined the causes of pilot incapacitation, one based on UK data and the other on US data. The UK CAA Study included incapacitation events affecting professional pilots both on and off duty and concluded that in the sample year (2004) “the annual incapacitation rate was 0.25%". It also found that cardiovascular and cerebrovascular conditions were the cause of 50% of recorded incapacitations.
The Recommendations in ICAO Annex 1 relevant to the medical risk of pilot incapacitation were considered by the investigation and opportunities for increasing regulatory awareness of the incapacitation risk were noted.
The Conclusions of the investigation included the following:
- The First Officer managed the flight deck efficiently after the Captain's incapacitation and whilst intending to carry out the landing as soon as possible, "he did not put himself under stress to perform a hasty approach". His actions "were in accordance with the Operator’s Operations Manual, Part A, for pilot incapacitation and reflected good airmanship".
- The Cabin Crew members who had assisted the First Officer had responded as per the Operator’s 'Operations Manual, Part A' and the 'Safety and Emergency Manual'.
- Crew resource management (CRM) "was practiced well in taking appropriate actions at proper times without putting the flight into a situation of increased risk".
- Medical data collection is a challenge when studying medical issues. The confidential nature of medical information may impede the collection of accurate data in a reasonable time. Medical condition data, especially for impairments rather than incapacitations, are rarely evaluated and categorised by a person who has adequate knowledge of medical implications.
- Although the incident aircraft was equipped with both left and right hand nose wheel steering tillers, it had remained on the runway for over half an hour only because the pilot seated in the right hand seat was not authorised by the Operator to taxi the Aircraft.
The Cause of the Captain’s incapacitation was the embolic event (stroke) that resulted in loss of consciousness.
Three Contributory Factors were also identified as follows:
- The Captain suffered from antiphospholipid syndrome disease which led to the embolic/stroke event.
- No additional information on the captain’s medical history, except his hypertension, was made available to the medical examiner, such that no further medical treatment was prescribed to mitigate the possibility of an embolic event.
- The regulatory requirements current at the time of the incident did not enable the medical check to discover a specific syndrome or disease, and subsequently to reduce the possibility of a pilot incapacitation event by taking the necessary medication or therapy.
Safety Action taken by the GCAA during and as a result of the Investigation to enhance the requirements for medical assessment of pilots applying for the renewal of Class 1 Medical Certificates included, in addition to the existing requirements for resting ECGs, that "extended cardiovascular assessment" must be undertaken when clinically indicated and that "estimation of serum lipids, including cholesterol" must be part of the first certificate-renewal examination after reaching the age of 40.
Six Safety Recommendations were made as follows:
- that Ethihad Airways should review the policy, assisted by appropriate risk assessment that prohibits taxiing an aircraft from the right hand seat, especially in emergency or abnormal situations. (SR 59/2015)
- that Ethihad Airways should ensure that its safety culture encourages voluntary disclosure of medical issues by the license holders. (SR 60/2015)
- that the General Civil Aviation Authority should consider enhancing medical data collection for medical events and pilot incapacitation, in order to identify any required risk mitigations. (SR 61/2015)
- that the General Civil Aviation Authority should conduct continuous testing of the medical assessment requirements, considering any newly arising medical risk. (SR 62/2015)
- that the General Civil Aviation Authority should include a cautionary statement in the license application form, which highlights the importance of disclosing an applicant’s medical history to the medical examiner. (SR 63/2015)
- that the General Civil Aviation Authority should promote an appropriate just culture across the aviation industry to widen the sources of medical data collection, including voluntary disclosures by applicant for the position of pilot. (SR 64/2015)
The Final Report was published on 20 September 2015.
- Pilot Incapacitation
- Medical Emergencies - Guidance for Flight Crew
- Crew Incapacitation: Guidance for Controllers
- The Annual Incapacitation Rate of Commercial Pilots, S. Evans & S. Radcliffe, Aviation, Space, and Environmental Medicine, Volume 83, Number 1, January 2012.