Vueling A320 near Marseille on Nov 17th 2017, both flight crew seriously &quot;inconvenienced&quot;
Last Update: November 3, 2020 / 19:02:25 GMT/Zulu time
The French BEA reported the occurrence was rated a serious incident and is being investigated. The crew felt strongly "inconvenienced" after climbing through FL100 out of Geneva, donned their oxygen masks, subsequently declared emergency and diverted to Marseille. Passengers and cabin crew were not inconvenienced.
On Nov 3rd 2020 the BEA released their final report in French and their final report in English (Editorial note: the following is based on the French report).
The BEA concludes in their report:
At the end of taxiing (for departure) and holding short behind a departing Cessna Citation the pilots of the A320 complained about an unpleasant smell and about irritations. During the climb the crew experienced partial incapacitation. Recognizing their partial incapacitation the flight crew requested supervision by the lead flight attendant and donned their oxygen masks, which permitted them to successfully divert and land without further incident.
Despite a broad spectrum of actions undertaken the investigation was not able to identify the origin of symptoms and discomfort experienced by the crew. The hypothesis of excessive inhalation of carbon monoxide, possibly from the exhaust gasses of the Cessna Citation ahead of the A320, is consistent with the information collected and may explain the symptoms (vertiges and nausea). Compounds of nitrogen oxides and sulphur oxides in the exhaust fumes may also have contributed to acrid odours and irritating feelings while flying. However, another substance can not be ruled out, which was able to dissipate quickly or was not specifically searched for in the items removed from the aircraft because they had not been identified relevant so far, including the most recent studies.
The detection of toxic substances used the most innovative and currently most efficient technologies. The BEA hypothesizes that the use of these technologies on samples of saliva, blood and urine taken at the shortest possible time after the symptoms, in particular as soon as possible after landing likely increases the chances of detecting a larger range of potentially toxic substances.
A safety investigation into flight crew incapacitation by inhalation of toxic products can provide information by seeking in particular the link between the presence of chemical compounds and symptoms experienced by the crew. This action is complementary to other areas of study and research that may be carried out by other organisations.
The events on which a safety investigation is to be initiated must be targeted in order to optimize the use of substantial investigative resources. Criteria for engagement should incorporate salience of symptoms and accessibility of assumed factual data.
The BEA reported the A320 was cleared to taxi to the holding point of runway 05 for departure and was taxiing behind a Cessna Citation. Both aircraft needed to stop at the holding point runway 05 and hold for some time. About 10 minutes after the A320 was cleared for their taxi route the Cessna Citation received takeoff clearance and commenced takeoff. A minute later the A320 was cleared for takeoff, winds were calm. Shortly after departure, while the gear was being retracted, a discussion between the A320 pilots arose about the intensity of the fumes encountered behind the Cessna Citation, the captain commented the odour almost caused him nausea, the first officer confirmed the smells were very intense.
Climbing through FL100 the captain inquires with ATC about the aircraft ahead of them during taxi and indicated he would file a report as result of cockpit odours. The first officer advised the captain, he felt "sick, intoxicated". ATC responds stating the aircraft was a Cessna Citation Excel and was following another departure trajectory. The captain advised the first officer that he now too felt unwell and proposed to add a little bit more air. Climbing through FL150 the A320 was handed off to enroute control and was cleared to climb to FL290. The crew requested the flight attendants to come to the cockpit, the crew inquired with the lead flight attendant who advised they did not feel anything and everything was going well in the cabin. The first officer stated he felt very disturbed by the aircraft ahead of them, the captain asked the flight attendant to leave the cockpit door open and an eye on the flight crew. 4 minutes later the captain comments he felt nausea, the first officer proposed a little more air and initiates the captain to don his oxygen mask. The first officer subsequently leaves the cockpit presumably for a toilet break according to CVR recordings. About 2:30 minutes later upon his return to the cockpit the captain inquires with the first officer how he feels, the first officer indicated he was feeling a bit better, he really was nauseaus too. The crew began to discuss a diversion in case of a worsening situation and selected Marseille as their diversion field. Another 5 minutes later the first officer also donned his oxygen mask, the captain declared PAN PAN and requested to divert to Marseille, the crew received landing information indicating to expect landing on runway 31. The captain requested runway 13 as the winds were calm and weather CAVOK. ATC granted the request 3 minutes later. The aircraft was vectored for the ILS approach to Marseille's runway 13L. While intercepting the localizer both crew advised they were feeling better, however, decided to keep their oxygen masks on until after landing, intercept of localizer and glideslope was flown on autopilot, at 195 feet AGL the autopilot was disconnected with the aircraft maintaining Vapp (135 KIAS). The aircraft lands without further incident. The flight crew is picked up at the apron and was taken to a hospital. Blood samples were taken and both crew were monitored for about two hours before being discharged. Both crew continued to suffer from nausea and dizziness alternating with lull for several more days.
The BEA analysed that the captain was pilot flying initially. The APU had been started about 10 minutes prior to departure. The A320 was taxiing behing a Netjets Cessna Citation and stopped behind the Cessna, about two lengths of aircraft behind the Cessna. The crew felt a quite pungent strong smell of exhaust gasses, the smell becoming more amplified and becoming very unpleasant, intense and acidic in nature. The crew stated from that moment on they felt tingling in their noses and throats and opened their airconditioning valves. The smell disappeared as soon as the Cessna Citation lined up and the crew agreed the smell originated from the business jet, no smoke was observed on board of the A320.
The BEA continued analysis that after departure the captain requested the chief flight attendant to the cockpit, queried about the status in the cabin, the purser reported the cabin was fine, none of the flight attendants felt anything unusual. The captain instructed the purser to remain in the cockpit and have an eye on them. While climbing to FL290 the first officer began to feel dizzy and had an urgent need for a toilet break and left the cockpit to urinate at the toilet. While alone in the cockpit with the flight attendant the captain felt his condition to worsen and donned his oxygen mask. The captain declared PAN PAN and requested the diversion to Marseille and gave instruction to the chief flight attendant in case his condition would worsen further. The first officer returned to the cockpit feeling unwell and also donned his oxygen mask. The first officer's condition improved with the oxygen mask on, hence the captain transferred controls to the first officer, who now assumed the role of pilot flying and the captain the role as pilot monitoring. The aircraft continued for a safe landing, after vacating the runway there was no follow me vehicle guiding them to the apron. The crew taxied to the apron with emergency services in trail. Nausea continued although both crew opened their side windows.
Both crew were taken to a hospital, blood samples were taken and the crew monitored for about two hours. Then the results of the blood samples indicated no carbon monoxide in their samples and the crew was discharged. No further toxicologic analysis was performed and the blood samples were not preserved.
Maintenance followed TSM Task 05-50-00-810-831-A in order to identify any cause of the odours but did not find any anomalies.
Flights in the following days and months did not experience any technical incidents or suspicious odours on the aircraft. In subsequent maintenance activities additional activities were carried out to locate sources of possible odours, but no anomalies were found.
The Cessna Citation was examined and the crew interviewed. The aircraft had undergone major maintenance between Aug 16th and Sep 29th 2017, during which the right hand engine had been removed for overhaul at Pratt and Whitney and following maintenance was approved for re-mount on the aircraft. Following that maintenance the aircraft flew 53 hours until the occurrence. Two days after the occurrence the metal particle detector in the right engine triggered, the oil filter was replaced and sent for analysis, no anomaly with the engine oil was found.
The Cessna had no MEL items open at the time of the occurrence, an oil leak test revealed no leaks. The Cessna flight crew did not notice anything unusual on their departure from Geneva.
Radar examination revealed the A320 was holding behind the Cessna for nearly 4 minutes. The winds were calm at the time, the axis of both aircraft suggested the conditions were conducive to the formation of a concentration of exhaust gasses at the front of the Airbus. The gasses could be ingested by the Airbus' engines and enter the cabin via the air conditioning systems (packs) mixing 60% of bleed air (ambient air) with 40% recircled air from the cabin. It is probable, as pack #1 supplies the cockpit, the ingestion of fumes occurred mainly by the left engine.
The combustion of kerosene produces, amongst other byproducts, carbon dioxide, water, nitrogen, oxygen, sulphur dioxides (SO2). Under certain conditions also nitrogen oxides (NOx), carbon monoxide, unburned hydro carbons and volatile organic compounds can occur. NOx have particularly pungent odours, SO2 a "spicy" smell. The crew reported pungent and acidic odours. However, the chemical compounds perceived by the crew may not be necessarily the ones responsible for the symptoms. In particular, carbon monoxide does not have any smell but may lead to incapacitation of the crew.
The negative result of the blood tests in the hospital can be explained by the time elapsed (more than an hour until the flight crew reached the hospital) and by the administration of oxygen by the oxygen masks, which may eliminate or reduce the levels of carbon monoxide in the blood.
No de-icing had taken place even though glycol used in de-icing fluids might contaminate the cabin air via the APU. The theory was dismissed due to lack of de-icing.
Cabin air can also become contaminated by fluid degradation products, e.g. hydraulic fluids, engine oils and other particles, these are subject of international studies.
In the engines seals are used to confine lubricants to rotating parts. It is commonly accepted that in the event of wear or deterioration of joints oil leaks can occur and small amounts of oil can mix with the air warmed by compression. Parts of this pyrolyzed oil can then pass through the cabin pressurization system and contaminate the cockpit. The extent of oil leakage varies with the condition of the joints, maintenance of the engine, engine thrust changes and engine design. Engine oil contains, amongst other things, TCP (Tri Cresyl Phosphates) at the highest level of about 3%. In case of pyrolysis small portions of the TCP may transform into ToCP (Tri Ortho Cresyl Phospate), an ortho isomeric of TCP and neurotoxic organo-phosphate. Studies of air quality in the cabin indicate, that ToCP can cause a variety of symptoms such as encountered by the crew. During such contaminations the odour of "wet socks" is often reported on board, which may be accompanied by smoke or mist in the cabin air. The smell sometimes may not be noticed though and becomes identifyable only by the symptoms.
The BEA has an interest in the possibility of contamination with TCP/ToCP in the context of this investigation and into cases of partial incapacitation as well as further studies in the subject.
In order to receive some data the BEA decided to collect hair samples from both flight and cabin crew. The samples were taken on Dec 22nd 2017 (optimum time 15 days to one month after the event). Pollutants such as TCP were identified in the samples however no peaks or changes in levels before, during and after the event, the levels were in line with environmental pollution. Contamination with TCP/ToCP was thus ruled out. However, this does not rule out the possibility of another substance which would be similiar but quickly dissipate.
The BEA analysed further that formalized reporting based on grids, criteria and questionaires may be insufficient to identify the phenomen in case of exploratory studies. The BEA therefore also collected the narratives by the crew in the language and wording of their choices, also expressing their feelings and experiences away from any formatted documents. This allows the emergency of information that "classic reports" may be omitting. Cross References of such information can reveal a coherence or coherence revealing discrepancies.
This article is published under license from Avherald.com. © of text by Avherald.com.
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