Fatigue can leave workers in a fog – which isn’t a good atmosphere for clear, safe decision-making. The crash of a 747 cargo jet at Halifax International Airport in mid-October 2004 is being blamed in part on flight crew fatigue.

Seven MK Airlines Ltd. crew members died when the big jet failed to gain sufficient altitude on takeoff, struck a berm at the end of the runway and crashed into an adjacent forest.

A Transportation Safety Board of Canada (TSB) investigation found that the speed and thrust settings selected by the crew in preparation for a flight to Spain were incorrect for the weight of the aircraft. The TSB says the crew did not receive adequate training on a computer program used to calculate takeoff velocity and necessary power for flight.

As a result the airplane was traveling about 30 knots (35 miles an hour or 56 kilometers an hour) slower than the 160 knots that would have been required for a safe takeoff with the load it was carrying.

Crew fatigue and a dark takeoff environment contributed to the crash, according to the board. It is calling for implementation of an on-board takeoff performance monitoring system "to ensure that crews of large aircraft will be alerted in time when there is not enough power to take off safely."

Such a device does not currently exist. Since the airplane’s flight voice recorder was destroyed in the crash, investigators do not know what the crew was saying in the seconds leading to the crash.

The TSB found evidence that 12 similar accidents involving insufficient power on takeoff had resulted in 300 deaths around the world. Your workplace probably has nothing to do with airplanes, but rocket science isn’t required to see how fatigue can put your workers at risk.