The National
Transportation Safety Board has determined that the cause of
an aircraft accident in Kirksville, Missouri was the pilots'
failure to follow established procedures and properly conduct a
nonprecision instrument approach at night in instrument
meteorological conditions (IMC). This included their descent below
the minimum descent altitude (MDA) before required visual cues were
available and their failure to adhere to the established division
of duties between the flying and nonflying pilot.
On October 19, 2004, Corporate Airlines flight 5966, a British
Aerospace "Jetstream" BAE-J3201, on a scheduled flight from Lambert
St. Louis International Airport, in St. Louis to Kirksville,
Missouri, struck trees and crashed short of the runway during a
night nonprecision instrument approach to Kirksville Regional
Airport. The 2 pilots and 11 of the 13 passengers were fatally
injured, and 2 passengers received serious injuries. Impact and a
post-crash fire destroyed the airplane. Night instrument
meteorological conditions prevailed at the time of the accident,
and the flight operated on an instrument flight rules flight
plan.
"It is imperative that pilots understand and follow proper
procedures when flying in demanding conditions," said NTSB Acting
Chairman Mark Rosenker (pictured below, right). "Pilots are also
expected to perform in a professional manner at all times when
operating an aircraft."
The Board noted that current regulations permitting pilots to
descend below the MDA into a region where obstacle clearance is not
assured may result in reduced margins of safety for nonprecision
approaches, especially in conditions of low ceilings, reduced
visibility, and/or at night. Further, these regulations can have
the unintended effect of encouraging some pilots to descend below
the MDA in an attempt to acquire visual cues that will permit them
to continue the approach, as evident in this case.
The Safety Board
indicated that the pilots failed to follow established procedures
to effectively monitor the airplane's descent rate and height above
terrain during the later stages of the approach and relied too much
on minimal external visual cues. Although descent rate and altitude
information were readily available through cockpit instruments,
both pilots were largely preoccupied with looking for the approach
lights, the report noted.
The Board determined that the pilots' failure to establish and
maintain a professional demeanor during the flight and fatigue
likely contributed to their degraded performance. The pilots'
nonessential conversation below 10, 000 feet was contrary to
established sterile cockpit regulations (no flight crewmember may
engage in any activity during a critical phase of flight which
could distract any crewmember from the performance of his or her
duties). It reflected a demeanor and cockpit environment that
fostered deviation from established standard procedures, crew
resource management disciplines, division of labor practices, and
professionalism, reducing the margin of safety well below
acceptable limits during the accident approach.
According to the Board's report, research shows that fatigue can
cause pilots to make risky, impulsive decisions, become fixated on
one aspect of a situation, and react slowly to warnings or signs,
which could result in an approach being continued despite evidence
that it should be discontinued. Through it's investigation, the
Board learned that the less than optimal overnight rest time
available, the early reporting time for duty, the length of the
duty day, the number of flight legs and the demanding flying
conditions were factors that affect any fatigue that the pilots may
have experienced. This supports the Board's finding that fatigue
likely caused the degraded performance and subsequent decision
making. Therefore, the Board concluded that providing pilots with
additional fatigue-related training may increase their awareness
and use of fatigue avoidance techniques and thus improve safety
margins.
Safety Board recommendations to the FAA as a result of the
investigation include:
- Directing the principal operations inspectors of all Part 121
and 135 operators to reemphasize the importance of strict
compliance with the sterile cockpit rule.
- Requiring all Part 121 and 135 operators to incorporate the
constant-angle-of-descent technique into their nonprecision
approach procedures and to emphasize the preference for that
technique where practicable.
- Revising Part 121 and 135 regulations to prohibit pilots from
descending below the
minimum descent altitude during nonprecision instrument approaches
unless conditions allow for clear visual identification of all
obstacles and terrain along the approach path or vertical guidance
to the runway is available and being used.