On June 2, 1990, about 0937 Alaskan daylight time, Markair, Inc., flight 3087, a Boeing 737-2X6C, N670MA, operating under 14 CFR Part 121, crashed about 7 ? miles short of runway 14 at Unalakleet, Alaska, while executing a localizer-only approach in IMC. One flight attendant received serious injuries; the captain, the first officer, and a flight attendant received minor injuries; and the aircraft was destroyed. The Safety Board determined that the probable cause of the accident was deficiencies in flight crew coordination, the crew's failure to adequately prepare for and properly execute the localizer-only runway 14 nonprecision approach, and the crew's subsequent premature descent.[1]
On April 3, 1996, a U.S. Air Force CT-43A (737-200) carrying the Secretary of Commerce, other Government officials, and a delegation of business executives crashed on a mountainside while on an NDB approach to Cilipi Airport in Croatia. All 35 people aboard the airplane were killed. The Safety Board provided technical assistance to the Air Force during its investigation.[2]
1.18.4 Industry Actions to Improve the Safety of Nonprecision Instrument Approaches Conducted by Air Carriers
1.18.4.1 Nonprecision Approach Procedures According to the Air Line Pilots Association (ALPA),[3] limited data indicate that airline transport crews conduct only about one to three nonprecision approaches per year and practice these approaches in a simulator "just as infrequently." Thus, ALPA concluded that the risk associated with this "inherently less safe type of approach" is compounded by the infrequency of flight crew exposure and practice. ALPA stated that most nonprecision approaches are presented in a series of step-down altitudes and that, although step-down altitudes may be satisfactory for light, slow, maneuverable aircraft, they are unacceptable for transport-category aircraft. ALPA further stated that these step-down altitudes are in fact directly contrary to the underlying concept of the stabilized approach because they require multiple power and pitch changes to be flown as charted. ALPA believed that approach charts and procedures should be modified to provide the information necessary to conduct a stabilized descent without explicit vertical guidance.
The issue of nonprecision approaches flown by air carrier (primarily turbojet) airplanes has been debated, especially in light of the recent CFIT accidents that occurred during the execution of a nonprecision approach. ALPA stated that "all turbojet air carrier airports need to have a precision approach available at all times in the appropriate landing direction." Further, ALPA believed that it is "problematic at best" for a "500,000 pound
- ↑ National Transportation Safety Board. 1991. Controlled Flight Into Terrain, Markair Flight 3087, Boeing 737-2X6C, N670MA, Unalakleet, Alaska. Aircraft Accident Report NTSB/AAR-91/02. Washington, DC.
- ↑ For more information, see the Air Force's Accident Investigation Board Report, United States Air Force CT-43A [Boeing 737], 73-1149, 3 April 1996, at Dubrovnik, Croatia.
- ↑ 166 See Air Line Pilots Association Report on Accident Involving Korean Air Flight 801 at Agana, Guam, on August 6, 1997, dated June 24, 1998.
