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.

FMI: www.ntsb.gov