I am always watching the news for interesting stories about fatigue and sleep. I came across a headline that read “British Airways flight was forced to make emergency landing at Heathrow with engine on fire after tired engineers completed work on the WRONG PLANE”.
This one stuck with me because of the schedule one of the aircraft maintenance engineers (AME) worked leading up to the accident and the fatigue related slip.
According to the news article, one of the AME’s had worked 70 hours in the seven days leading up to the incident. Although 70 hours is a lot to work in week, it really only means 10 hours per day. You could work from 08:00 to 18:00 and still get your eight hours of sleep every night. This would not guarantee that you would find yourself fatigued on the job.
Amateur Video Showing the Open Cowling
But the AME did not work this consistent pattern. Instead, the last two shifts were 12 hour overtime night shifts. Now this is a different situation all together. This would mean that the AME worked a little over nine hours during the day or evening for five days and then pulled two graveyard shifts of 12 hours. This schedule would almost guarantee fatigue on the job and likely to the level that would cause lapses in attention. This is probably how the AME slipped up and returned to work on a different aircraft. This left the engine cowlings on the original aircraft unlatched. The loose cowlings blew off during take off and ruptured a fuel line causing the engine to burst into flames.
So just how fatigued was the AME? I ran a best case schedule through FAID to check. Here’s what the results looked like for the AME’s last night shift, the one where the slip took place.
This graph shows that for the last five hours of the shift, the AME would have been just as fatigued as someone who had been awake for 21 hours straight and that the AME’s performance would have been very similar to someone with a blood alcohol concentration of over 0.05%. That’s in the legal “warning range” for Ontario. The point were police can take you off the road and temporarily suspend your license.
The results also show that at about 07:00, the AME’s fatigue would have been so bad that performance would have been similar to someone with a BAC of 0.08%. You would be arrested for driving in that condition.
What is one thing we learn from this? The first thing that pops in my head is that, although the total hours of work are important and that overtime should be limited, you have to also consider the time of the work periods to best manage fatigue.
 For the full news story see: http://www.dailymail.co.uk/news/article-3160354/British-Airways-flight-forced-make-emergency-landing-Heathrow-engine-fire-tired-engineers-completed-work-WRONG-PLANE.html
 FAID is a bio-mathematical model of human fatigue resulting from work and rest patterns. It is based on the pioneering work of Dr. Adam Fletcher: Fletcher, A. (1999). Measurement and management of work-related fatigue: Development and preliminary validations of a predictive model. Ph.D. Thesis, 1999, The University of South Australia.