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General Aviation Safety
ON JANUARY 13, 1982, AIR FLORIDA FLIGHT 90, A BOEING 737-222 (N62AF) STRUCK THE NORTHBOUND SPAN OF THE 14TH STREET BRIDGE WHICH CONNECTS THE DISTRICT OF COLUMBIA WITH ARLINGTON, COUNTY, VIRGINIA, AND PLUNGED INTO THE ICE-COVERED POTOMAC RIVER JUST AFTER TAKING OFF FROM WASHINGTON NATIONAL AIRPORT. SEVENTY OF THE 74 PASSENGERS, 4 OF THE 5 CREWMEMBERS, AND 4 PERSONS IN VEHICLES ON THE BRIDGE WERE FATALLY INJURED. THE WEATHER CONDITIONS WHICH HAD PREVAILED BEFORE AND AT THE TIME OF THE ACCIDENT CONSISTED OF SUBFREEZING TEMPERATURES AND ALMOST STEADY MODERATE TO HEAVY SNOWFALL WITH OBSCURED VISIBILITY.
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE TO IMPLEMENT THE NECESSARY AIRPLANE MODIFICATIONS AND/OR CHANGES IN OPERATIONAL PROCEDURES FOR B-737 AIRCRAFT TAKEOFF OPERATIONS DURING WEATHER OR RUNWAY CONDITIONS CONDUCIVE TO THE FORMATION OF LEADING EDGE FROST, SNOW, OR ICE CONTAMINATION TO REQUIRE EITHER: (1) THAT THE LEADING EDGE IS FREE OF FROZEN CONTAMINANT THROUGH THE PRE-TAKEOFF USE OF A GROUND-OPERABLE WING THERMAL ANTI-ICE SYSTEM, OR (2) AN INCREASED STALL AIRSPEED MARGIN AT LIFTOFF WHICH WILL PROVIDE ADEQUATE PITCH AND ROLL CONTROL TO COUNTER THE EFFECTS OF UNDETECTED LEADING EDGE CONTAMINANTS BY MODIFICATION OF TAKEOFF FLAPS CONFIGURATION AND/OR INCREASE TAKEOFF AIRSPEED SCHEDULES.
Original recommendation transmittal letter:
Closed - Unacceptable Action
Washington, DC, United States
Air Florida, Inc., Boeing 737-222, N62AF, Collision with 14th Street Bridge
Addressee(s) and Addressee Status:
FAA (Closed - Unacceptable Action)
Icing, Upset Recovery, Weather
Safety Recommendation History
We note that the FAA has taken two specific actions which pertain to this recommendation. First, the FAA approved, on January 14, 1983, a modification to the Boeing-737 wing thermal anti-ice system which permits its use during ground operations. In order to utilize the wing thermal anti-ice system during ground operations, operators must purchase and install appropriate modification kits. Secondly, the FAA has approved changes to the Boeing-737 AFM which include information for achieving improved stall margins, when excess runway is available, by use of increased takeoff airspeed schedules for selected flap settings. This revised AFM is planned for issuance to all operators by June 1983. Similar information has already been sent to all operators in a revised Boeing-737 Operations Manual. The Safety Board acknowledges that the FAA has acted on both issues addressed in this recommendation - the use of wing thermal anti-ice during ground operation, and the use of increased takeoff speeds during operation in adverse weather conditions. However, we remain concerned that the FAA's actions do not require implementation and/or use of either option. In the case of the wing thermal anti-ice system, modification compliance is voluntary on the part of the operator. The increased takeoff speed option is suggested for use when excess runway is available, and there is no mention of imposing a weight penalty to achieve the same objective in the case where excess runway is not available. The FAA does not agree with issuing an Airworthiness Directive (AD) to require implementation and use of the measures described above. The FAA believes that AD action is not justified since the flightcrew is required to assure that the wing leading edges are free of contamination before takeoff. As stated in previous correspondence, the Safety Board agrees with the FAA that strict adherence to the provisions of 14 CFR 121.629(b) is imperative to safe operations during ground icing conditions. Notwithstanding this view, we remain concerned that during reduced visibility conditions and during night operations, it is unrealistic to expect that Data Source: NTSB Recommendations to FAA and FAA Responses flightcrews will be able to detect small accumulations of ice or snow adhering to the wing leading edges. The Safety Board continues to believe that the FAA should mandate either airplane system modification or performance adjustment. However, we do not have any additional information to provide FAA in support of this recommendation. Therefore, Safety Recommendation A-82-83 has been classified as "Closed--Unacceptable Action."
FAA LETTER: THE FAA CANNOT AGREE WITH ISSUING AN AIRWORTHINESS DIRECTIVE. THE FAA DOES AGREE THAT FLIGHT CREWMEMBERS AND OPERATORS SHOULD BE AWARE OF THE OVERSPEED TAKEOFF OPTION AND THAT 3 DEGREES PER SECOND ROTATION RATES SHOULD BE OBSERVED. THEY SHOULD ALSO BE AWARE THAT THE GROUND THERMAL ANTI-ICING (TAI) SYSTEM PROVIDES ADDITIONAL ASSURANCE THAT UNDETECTED ICING CONTAMINANTS ON THE WING LEADING EDGE OF A PROPERLY DEICED/ANTI-ICED AND INSPECTED AIRCRAFT CAN BE MELTED. THE FAA AND THE MANUFACTURER HAVE TAKEN RESPONSIBLE ACTIONS TO DISSEMINATE PROPER OPERATING PROCEDURES AND TO AMPLIFY THOSE REPORTS IN OUR PREVIOUS RESPONSE ON THIS SUBJECT. A REVISED BOEING 737 OPERATIONS MANUAL HAS BEEN SENT TO ALL B-737 OPERATORS. INCLUDED IN THE SUPPLEMENTARY PROCEDURES REVISION IS INFORMATION FOR IMPROVED STALL MARGINS, WHEN EXCESS RUNWAY IS AVAILABLE, BY USE OF IMPROVED CLIMB (TAKEOFF OVERSPEED) PROCEDURES FOR SELECTED FLAP POSITIONS. THE BOEING 737 FAA-APPROVED AIRPLANE FLIGHT MANUAL (AFM) IS ALSO BEING REVISED TO INCLUDE SIMILAR INFORMATION AND IS PLANNED FOR ISSUANCE TO ALL OPERATORS BY JUNE 1983. INCORPORATING THIS INFORMATION INTO THE TWO MANUALS ASSURES ITS AVAILABILITY TO ALL OPERATORS, AUGMENTING ON A PERMANENT BASIS THE OPERATIONS MANUAL BULLETIN 81-4 DATED JUNE 5, 1982. ON JANUARY 14, 1983, THE FAA APPROVED THE B-737 GROUND TAI SYSTEM. ASSOCIATED WITH THE APPROVED IS A REVISION TO THE FAA-APPROVED AFM WHICH STIPULATES THAT THE SYSTEM IS NOT TO BE USED AS A SUBSTIUTE FOR GROUND DEICING/ANTI-ICING AND INSPECTION PROCEDURES WHICH ARE NECESSARY TO COMPLY WITH OPERATING RULES. THIS MEASURE WAS TAKEN TO CLARIFY THE INTENDED PURPOSE OF THE SYSTEM AND TO INHIBIT FLIGHTCREW RELIANCE ON THE SYSTEM AS A PROCEDURAL ALTERNATIVE.
The Safety Board acknowledges that the FAA's actions in publishing the "Winter Operations Guidance for Air Carriers" which contains extensive information to enhance cold weather operational safety will be highly useful. The Safety Board also agrees with the FAA view that strict adherence to the requirements of 14 CFR 121.629(b) is imperative to safe operations and that such adherence will meet many of the hazards associated with winter operations. However, we share the view of the United Kingdom Civil Aviation Authority (CAA) that safety measures also must include maximizing the takeoff safety margin in the event that a flightcrew is not able to detect small accumulations of leading edge contaminant as seen from the inside of the airplane, particularly during night operations. The Safety Board has been informed that the Boeing Company has made progress in developing a ground operable wing thermal anti-ice system for the B-737. We remain concerned, however, that the availability of this system, related modification kits and any forthcoming airworthiness actions will not be timely for the current cold weather season. The Safety Board believes that the pitchup or rolloff characteristic of the B-737 has been sufficiently documented in reports from pilots to warrant FAA and operator concern. For this reason, the Safety Board continues to believe that interim actions to increase takeoff speed margins under defined adverse weather conditions are needed. Until such actions are taken or an Airworthiness Directive is issued directing wing thermal anti-ice system modification and procedures, the Board will classify this recommendation as "Open--Unacceptable Action."
FAA LTR: THE FAA HAS NOT YET DETERMINED IF THE B-737 IS, IN FACT, MORE SENSITIVE THAN OTHER AIRPLANES TO THE PITCH UP/ROLLOFF PHENOMENON. PENDING COMPLETION (MID-1983) OF WIND TUNNEL, SIMULATOR AND FLIGHT TESTS BEING CONDUCTED BY BOEING COMPANY, THE FAA HAS CONCLUDED THAT THE CHANGES REQUESTED IN THE RECOMMENDATION WOULD BE PREMATURE.
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