The Air Accidents Investigation Branch of the UK’s Department of Transport implicated jet lag and over-the-counter drugs in the crash of Bombardier Challenger 604 N90AG, in Birmingham, England, on Jan. 4, 2002. The failure of the impaired crew, which had taken antihistamines the night before, to have the airplane de-iced before takeoff may have caused the jet’s stall, roll to the left and crash on takeoff, concluded the DoT. The aircraft was destroyed and there were no survivors. Operated and maintained by Epps Air Service, N90AG was owned by Fleet National Bank and leased to Agco.
The day before the crash, the crew’s tour of duty started at Dekalb-Peachtree Airport in Atlanta at 4 a.m. (9 a.m. Birmingham time). They flew to Fort Myers Airport, Fla. for a 25-minute stop to pick up a passenger, then flew to West Palm Beach Airport (PBI) to pick up another passenger. After a 29-minute stop, the aircraft left PBI at 12:59 Zulu and arrived at Birmingham at 8:39 p.m. (3:39 p.m. in Atlanta).
The Epps Air Service crew consisted of the commander, designated as pilot in command but who flew right seat, and the handling pilot, in the left seat, who was one of four company captains qualified on the Challenger. Both had worked for Epps since 1968 and the PIC was the director of operations. Another company pilot, who was not qualified in the Challenger 604, was on the trip to observe the transatlantic experience.
The airplane sat outside overnight. There was no precipitation but the air temperature remained below zero all night and Birmingham Airport was under a severe frost, which had improved to moderate by the time of the accident. The crew stayed at a local hotel, had dinner, accompanied by about “five units of alcohol,” between 9:44 p.m. and 11:15 p.m., and retired after that (approximately 6 p.m. in Atlanta, a 14-hour day). The left-seat pilot made a telephone call at 2 a.m. Both the left-seat pilot and the PIC took an over-the-counter antihistamine containing diphenhydramine, an ingredient in Excedrin PM and Nytol. The accident investigators could not determine whether the pilots took the medication because both had colds or to overcome jet lag.
OTC Drugs Impair Pilots’ Judgment
At approximately 10:40 the next morning, the left-seat pilot and the observer pilot arrived at the aircraft, and they started the APU about 10 minutes later. The commander arrived at approximately 11 a.m. Each crewmember independently inspected the exterior of the aircraft. Refueling took 35 minutes, ending at about 11:40 a.m. The two passengers who had flown over on the airplane the day before boarded.
During the morning, witnesses had seen frost/ice on the wing surfaces of N90AG, and other aircraft, with severe to moderate ice accumulation, had been de-iced. The captain of a Canadair CRJ that had been parked near N90AG decided at about 10:30 a.m. that the CRJ needed de-icing; the frost was some one to two millimeters thick over the aircraft surfaces. The crew of N90AG discussed the presence of frost on the leading edge before engine start, but neither pilot requested de-icing and N90AG was not de-iced. The left-seat pilot was vague on the subject of the ice and it was not mentioned again. The DoT considered it highly unusual that the pilots would not have discussed and agreed upon a solution to the frost situation.
Heat from the APU exhaust gas may have reduced, eliminated or smoothed the frost on the right wing, resulting in an asymmetric condition that accentuated the tendency for the left wing to stall first. The Birmingham weather report at 11:50 a.m. was surface wind 150 degrees at six knots, visibility 8,000 meters (approximately five miles), cloud scattered at 700 feet agl and broken at 800 feet agl, temperature -2 degrees C with dew point -3 degrees C. The crew started the engines, and at 12:01 p.m. the airplane was cleared to taxi to Runway 15.
Takeoff appeared normal until liftoff. Immediately after liftoff, the aircraft started to bank to the left. The left winglet contacted the runway shoulder around 3.5 seconds after liftoff, with the aircraft banked around 80 degrees left. The aircraft struck the ground, inverted, adjacent to the runway.
Although investigators could not be sure exactly where the passengers and observer pilot were seated, they determined that the aircraft would have been within the originally certified normal weight and c.g. limits for takeoff. The estimated takeoff weight would have been 47,836 pounds, within mtow limits.
Although the left-seat pilot reacted well to the uncontrolled roll, displaying a high level of motor skills, said the report, both pilots showed some deficiencies in judgment and concentration in the period between arriving at the aircraft and the takeoff roll. Both exhibited symptoms of decreased concentration and judgment and it was possible that the combination of jet lag, tiredness and the effects of diphenhydramine caused these symptoms. The effects of each combined to impair the ability of the pilots to deal with the situation they faced.
Studies at the University of Iowa compared diphenhydramine with alcohol in a driving simulator. The performance of the participants was poorest after they took diphenhydramine, indicating that the drug had a greater effect on driving than alcohol. The report also noted that nonprescription drugs were found in 18 percent of the pilots killed in flying accidents in the U.S. between 1994 and 1998. Of these, diphenhydramine, found on 54 occasions, was the most common drug.
The report recommended that the UK Civil Aviation Authority require flight manuals of aircraft with a significant susceptibility to ice contamination to say: “Wings and tail surfaces must be completely clear of snow, ice and frost prior to takeoff,” and communicate this recommendation to other civil airworthiness authorities responsible for the primary type certification of new aircraft.
The report also recommended that the FAA and EASA review the current procedural approach to the pre-takeoff detection and elimination of airframe ice contamination and consider requiring a system that would directly monitor aircraft aerodynamic surfaces for ice contamination and warn the crew of a potentially hazardous condition.
In addition, the report recommended that the FAA act upon the January 2000 NTSB recommendations to review the guidance given to flight crews about the dangers of using non-prescription medication and to ensure that medication packaging contains appropriate warnings about possible side effects.
The fact that two experienced and safety-conscious pilots used medication containing diphenhydramine indicated to the investigators that crews may not be sufficiently aware of the potential dangers of using nonprescription medications.