The National Transportation Safety Board today determined that the probable cause of an aviation accident in Aspen, Colorado involving a Gulfstream III was the flight crew's operation of the airplane below the minimum descent altitude without visual reference to the runway. Contributing to the accident was the Federal Aviation Administration's (FAA) unclear wording of a Notice to Airmen (NOTAM) regarding the nighttime restriction of the VOR/DME-C approach to the airport. Also cited as contributing factors were the inability of the flight crew to adequately see the mountain terrain because of the darkness and weather conditions, the pressure from the charter customers for the captain to land the airplane, and the delayed departure of the airplane from California, causing the flight to arrive at sunset during the airport's nighttime landing restrictions.
On March 29, 2001, a Gulfstream III owned by Airbourne Charter, Inc. and operated by Avjet Corporation of Burbank, California, with 15 passengers, 2 pilots and 1 flight attendant, crashed on final approach to runway 15 at Aspen-Pitkin County Airport (ASE). The airplane crashed into sloping terrain about 2,400 feet short of the runway threshold. All persons aboard the aircraft died.
The Safety Board's investigation determined the following facts: (1) the flight crew descended below the minimum descent altitude even though the airplane maneuvers and comments on the cockpit voice recorder indicated that neither pilot had established nor maintained visual contact with the runway or its environment; (2) the flight crew did not discuss a missed approach after receiving a third report of a missed approach to the airport and a report of deteriorating visibility in the direction of the approach course; and (3) a copy of the FAA issued NOTAM on March 20, 2001, stating "circling not authorized at night for runway 15 at Aspen" had not been sent to the Aspen tower. Without knowledge of the NOTAM, the approach controller cleared the flight crew for the VOR/DME-C instrument approach procedure.
Following the accident, the FAA became concerned about potential pilot confusion regarding the wording of the NOTAM -- specifically, that pilots might infer that straight-in landings to runway 15 were authorized at night. On March 30, 2001, a revised NOTAM was issued stating, "procedure not authorized at night."
In light of the fact that in mountainous terrain night conditions can exist prior to sunset due to the geography and ambient lighting conditions, the Safety Board issued an emergency Safety Recommendation on April 15, 2002 asking the FAA to:
"Revise any restrictions and prohibitions that currently reference or address 'night' or 'nighttime' flight operations in mountainous terrain so that those restrictions and prohibitions account for the entire potential period of darkness or insufficient ambient light conditions, and establish a method to clearly communicate to flight crews when such restrictions and prohibitions apply.
Following today's Board meeting, the Safety Board made the following recommendation to the FAA:
Revise 14 Code of Federal Regulations Part 135 to require on-demand charter operations that conduct operations with aircraft requiring two or more pilots to establish a Federal Aviation Administration approved crew resource management training program for their flight crews in accordance with 14 CFR Part 121, subparts N and O.
The complete report will be available on the website in about one month. Printed copies of the report may be purchased later this spring from the National Technical Information Service (NTIS) (800) 553-NTIS.