Monday, June 30, 2003
NTSB Cites Maintenance Worker Fatigue in Air Midwest Crash
Maintenance technician fatigue may have played a major role in the fatal crash of an Air Midwest Beech 1900D at Charlotte, N.C., Jan. 8. Work degradation from fatigue is well documented. When people get tired, they lose initiative, self-discipline and attention to detail.
The time sheets examined by National Transportation Safety Board (NTSB) maintenance investigators shows critical maintenance steps were skipped the night the elevator control cables were tightened on the aircraft. The time sheets reveal that maintenance workers were logging long hours at the Raytheon Aerospace [Nasdaq: BEAV] maintenance facility in Huntington, W.Va.
Technician Brian Zias, who was most involved in adjusting the cable tension, worked 14 hours the night the accident airplane was in the hangar. Quality assurance inspector George States, who was training Zias and approved his work on that task, worked 15.5 hours. Foreman Rick Tucker worked a 15-hour shift.
Struck by the hours being worked at this facility, maintenance expert Bart Crotty observed that management work control efforts should have the following underpinning principles:
1. Minimize the build up of fatigue over periods of work.
2. Maximize the dissipation of fatigue over periods of rest.
3. Minimize sleep problems and circadian disruptions.
Crotty said no more than 60 hours should be worked, including overtime, during a seven-day week period. Zias was well on the way to exceeding Crotty's suggested total in four days.
Crotty said, "A span of successive night shifts involving 12 or more hours of work should be limited to six shifts of up to eight hours long, four shifts of 8.1 to 10 hours, and two shifts of 10.1 hours or longer."
"These limits should not be exceeded by overtime," he admonished. For the source of these guidelines, he pointed to a recent paper by the UK's Civil Aviation Authority, "Work Hours of Aircraft Maintenance Workers," that provides the latest word on the subject. The paper suggests a 13-hour limit on the total period of work. On the night the Midwest Airlines aircraft was in for maintenance, all three of the individuals most directly involved worked more than 13 hours.
--This article was written by David Evans of Air Safety Week
>> Contact:Bart Crotty, e-mail: email@example.com; tel.: 703-569-4431 <<
|Working Tired: Air Midwest Crash Time sheets over a 3-day period|
|Individual||Hours worked night of Jan. 4, 2003||Hours worked night of Jan. 5, 2003||Night of Jan 6, 2003 (night accident airplane was serviced)||72-hour total|
|Brian Zias, Technician||17.5 hrs.||8 hrs.||14 hrs.||40.5 hrs.|
|George States, QA inspector||19.0 hrs.||9.5 hrs.||15.5 hrs.||44 hrs.|
|Rick Tucker, Foreman||Off Duty||8 hrs.||15 hrs.||23 hrs.|
What the people involved had to say in post-accident interviews with investigators (Note: people are not good judges of their state of fatigue):
Q: What is your normal sleep schedule?
A: Normally, I get off at 6:30 in the morning, so go home and shower up, out (asleep) by 8:00 and up around 4:00 or 5:00.
Q: How was your sleep in the days before Jan. 6?
A: Okay, as far as I know.
Q: Do you recall what time you woke up on the 6th?
Q: When do you normally -
A: Normally, I get off my shift and I go to sleep ... but sometimes I have errands to run or whatever, I will extend my - instead of going to bed like you would at 11:00, I'll go to bed at 1:00 or whatever.
Q: How do you handle fatigue management on a personal basis?
A: If I feel tired, I go home.
Q: That's your normal sleep/wake cycle. Do you normally go to bed -
A: I normally get up an hour or two before I've got to come to work. When I go to sleep, it all depends on what was going on that night on that shift. Sometimes it's as soon as I get back to the room and sometimes I'm up for a little while.