Background
On June 4, 1984, an unmodified Gates Learjet 23A, registration N101PP, operated by Air Continental, Inc., of Elyria, Ohio, conducted a regularly scheduled cargo flight under 14 CFR 135. The flight, designated Night Air 4, transported cancelled bank checks. It departed Cleveland-Hopkins International Airport at 2200 eastern daylight time.
Flight Sequence
After an uneventful flight, Night Air 4 arrived at Syracuse-Hancock International Airport at 2245. The airplane underwent routine ground cargo handling but was not refueled. Departing Syracuse at 2311, the flight was cleared to climb to 17,000 feet and was handed off to Boston Air Route Traffic Control Center (Boston Center) at 2314. Boston Center cleared Night Air 4 to its requested altitude of FL290, and the en route portion was uneventful. At 2332, during descent to Bradley International Airport, Windsor Locks, Connecticut, Night Air 4 was handed off to Bradley Approach Control at 16,000 feet. Approach control identified the aircraft, cleared it for a visual approach to runway 33, and at 2336 directed a turn to position the airplane on final approach at 10 miles from the airport. At 2338:22, Night Air 4 reported being on final approach for runway 33; at 2338:25, the air traffic control tower operator cleared the flight to land. At 2341:18, the control tower operator notified approach control of an accident at the airport.
Accident Witness Accounts
Fifteen witnesses interviewed described essentially the same accident sequence, with minor discrepancies. The airplane appeared to be on a normal approach to runway 33 with no apparent abnormalities. When the airplane was approximately 200 feet above the approach lights, an increase in engine thrust was heard, and the airplane halted its rate of descent—two pilot witnesses believed this indicated an attempt to go around. Immediately after, Night Air 4 began what appeared to be a level turn to the right. As the turn progressed through about 90 degrees, the wings became nearly vertical. The airplane's nose dropped below the horizon, and it descended into the ground in a nose-low attitude. Witnesses reported an explosion followed by intense ground fire. No significant lateral or vertical changes were noted during the short final or the right turn before impact. Many witnesses saw some lights illuminated on the aircraft but none reported seeing the landing lights (located on the landing gear) or the landing gear extended. No inflight fire, smoke, or airframe separation was reported before the crash. All three occupants were killed: pilot Charles Huffman, copilot Ronald Dulay, and passenger Eldridge Sheetz.
Probable Cause
The National Transportation Safety Board determined the probable cause of the accident was an uncommanded roll to the right, which caused the airplane to roll about 90 degrees and descend into the ground. The uncommanded roll resulted from an asymmetric retraction of the flight spoilers: the left spoiler retracted while the right spoiler did not. The Safety Board could not determine the reason for the right spoiler malfunction.