Contaminated Air
Flight Safety and Aircraft AccidentSource: Aviation Contaminated Air Reference Manual
So Where Are We Today? © 10th April 2008 by Susan Michaelis There is no common logic within emergency checklists in connection with a contaminated air event, an issue that hardly gives crews a clear picture of what is expected. Some education of these issues has been carried out by unions but not by the airlines or the regulators, which significantly reduces the value of such education. This is clearly shown in Appendix 2 where UK known incidents in 2005 show the variety of crew response when faced with a contaminated air event.
The lack of education combined with an industry also saying that contaminated air is harmless needs to be addressed. Passengers continue to be treated like canaries in a cage and told nothing, because if they suffer ongoing effects it will be most likely once they have left the aircraft anyway. Despite the clear statement in the BAe SB 21-150 that:
‘In the past oil leaks and cabin / flight deck smells and fumes may have come to be regarded as a nuisance rather than a potential flight safety issue. However, whilst investigations are being carried out to determine the nature of any agents that may be released into the cabin environment and to define any necessary corrective actions, oil leaks and cabin flight deck smells must be regarded as a potential threat to flight safety not just a nuisance.’
This is exactly what is still happening.
Most accident investigation branches who have investigated these issues have acknowledged that crews are still not taking contaminated air events seriously. The Canadian Transport Bureau Interim report on Swissair 111 accident in 2000 [3] states,
‘… recognition that within the aviation industry there has been belief that odours are often a non event, diminishing concern about minor odours.’
The UK AAIB have stated:
‘Other incidents have indicated that crews are not always fully alert to the possibility of air contamination on aircraft and have not always taken the most appropriate action’ and ‘In general, crews had regarded these events as a nuisance rather than a hazard, although their reactions and reported symptoms had been somewhat varied.’ [114]
The extremely worrying part about all of this, irrespective of the medical effects, is that if there is an accident it will be no accident as everyone knew about it. A comment made very well in the AOPIS documentary – Contaminated Air: An Ongoing Health and Safety Problem.
In fact it is no longer possible to state that there has never been an aircraft fatal accident in which contaminated air played a role or a contributory role. In 2005 a Boeing 737 operated by Helios Airways from Larnaca to Athens was lost with no survivors. [115] The direct causes given were: ‘non-recognition that the cabin pressurization mode selector was in the MAN (manual) position during the performance of the Pre-flight procedure, the Before Start checklist and the After Takeoff checklist; non-identification of the warnings and the reasons for the activation of the warnings (Cabin Altitude Warning Horn, Passenger Oxygen Masks Deployment indication, Master Caution) and incapacitation of the flight crew due to hypoxia, resulting in the continuation of the flight via the flight management computer and the autopilot, depletion of the fuel and engine flameout, and the impact of the aircraft with the ground.’ However, importantly and for the first time, the accident report states on page 70 and 103:
Aircraft technical log entry, 18/6/05:
‘Discrepancy; Unusual smell in cabin on ground with APU bleed supplying Packs.’
‘Maintenance action: Both LH-RH Packs suspected for oil contaminant. Turbofans suspected. APU as bleed source for two and half hours. Not possible to recall problem. Seems to be intermittent. Please Report Further.’
Functional tests of the flight deck oxygen masks using could not be performed due to excessive damage and presence of substances (grease, oil, soil).
It is clear that the cause of the accident was as listed above by the Greek investigating body. However, the fact that oil contamination was suspected a month prior to the accident and dismissed with, ‘Please report further’, and the now well known problem of oil contamination and under reporting, oil contamination cannot be ruled out as having played a contributory role. The failings of the maintenance system to identify faults & the problems of ongoing low level residual contamination cannot be ignored. However regrettably it appears they have been ignored. The head of the Greek investigating authority (AAIASB) was contacted soon after the accident and briefed by the author and Captain Tristan Loraine in Athens that oil contamination may have been a factor in the accident, dismissed this possibility outright and said ‘it’s an unproven science.’ While he was given more than a dozen names of experts to discuss the issue with, air accident reports from other contaminated air events and papers clearly showing exactly what subtle incapacitation could do, it was clear the information was not welcome. It appears that none of the dozen names was ever contacted. Surely any investigation should eliminate all possibilities before suggestions are discounted as an ‘unproven science’.
In Summary
Contaminated air or suspected contaminated is compromising flight safety not infrequently;
Contaminated air is causing adverse effects in crews in flight and impairing performance;
An industry wide education is urgently needed to ensure crews use oxygen in all cases of suspected or actual contaminated air;
Checklists need to be brought into a common theme of taking contaminated air seriously;
Contaminated air detection system is urgently needed;
Cabin crew need an oxygen system similar to pilots to ensure they can properly evacuate an aircraft in 90 seconds;
Regulations to protect crews and passengers from contaminated air do exist but are being ignored;
Passengers need to be advised they have been exposed to contaminated air;
A database of events needs to be internationally collated.
Flight Safety Aspects of Contaminated Air
Reporting Contaminated Air Events with Samples of Known Events
FODCOM (Flight Operations Department Communication) number 17/2000
FODCOM (Flight Operations Department Communication) number 14/2001 and 21/2002
Aviation Regulators Misinterpret Main Ventilation Airworthiness / Safety Standard
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References
3. Canadian Transport Bureau Interim report on Swissair 111 Accident. December 2000.
114. AAIB: March 2004 Aircraft Accident Report No: 1/2004 (EW/C2000/11/4) G-JEAK of 5 November 2000.
115. AAIASB. Air Accident Investigation & Aviation Safety Board (AAIASB) - Greece. Helios Airways Flight - HCY522 Boeing 737-31S at Grammatiko, Hellas On 14 August 2005.
