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Safety Recommendation Details

Safety Recommendation A-79-105
Details
Synopsis: THE NATIONAL TRANSPORTATION SAFETY BOARD HAS COMPLETED ITS DETERMINATION OF PROBABLE CAUSE AND FINAL REPORT ON THE AMERICAN AIRLINES DC-10 ACCIDENT IN CHICAGO ON MAY 25, 1979. THE SAFETY BOARD'S ANALYSIS OF THE EVIDENCE, AND RECOMMENDATIONS SUBMITTED TO THE BOARD BY THE OTHER PARTIES WHO PARTICIPATED IN THE INVESTIGATION AND PUBLIC HEARING, HAVE IDENTIFIED SEVERAL AREAS WHICH WE BELIEVE REQUIRE THE FEDERAL AVIATION ADMINISTRATION'S EARLY ATTENTION.
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: REVISE OPERATIONAL PROCEDURES AND INSTRUMENTATION TO INCREASE STALL MARGIN DURING SECONDARY EMERGENCIES BY: (A) EVALUATING THE TAKEOFF-CLIMB AIRSPEED SCHEDULES PRESCRIBED FOR AN ENGINE FAILURE TO DETERMINE WHETHER A CONTINUED CLIMB AT SPEEDS ATTAINED IN EXCESS OF V2, UP TO V2 + 10 KNOTS, IS AN ACCEPTABLE MEANS OF INCREASING STALL MARGIN WITHOUT SIGNIFICANTLY DEGRADING OBSTACLE CLEARANCE. (B) AMENDING APPLICABLE REGULATIONS AND APPROVED FLIGHT MANUALS TO PRESCRIBE OPTIMUM TAKEOFF-CLIMB AIRSPEED SCHEDULES; AND (C) EVALUATING AND MODIFYING AS NECESSARY THE LOGIC OF FLIGHT DIRECTOR SYSTEMS TO INSURE THAT PITCH COMMANDS IN THE TAKEOFF AND GO-AROUND MODES CORRESPOND TO OPTIMUM AIRSPEED SCHEDULES AS DETERMINED BY (A) AND (B) ABOVE.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: Chicago, IL, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA79AA017
Accident Reports: American Airlines, Inc., DC-10, N110AA
Report #: AAR-79-17
Accident Date: 5/25/1979
Issue Date: 12/21/1979
Date Closed: 5/17/1983
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 5/17/1983
Response: The safety board has evaluated the faa's actions in response to this recommendation as appropriate and complete. These actions should enhance safety in the event of an aircraft emergency during the takeoff and initial climb phases of flight. Safety recommendation a-79-105 is classified as closed--acceptable action. The safety board appreciates the faa's attention to these recommendations although, we remain concerned that some key problems evidenced in the american airlines dc-10 accident regarding faa surveillance and service difficulty analysis programs have not, in our view, been satisfactorily solved.

From: FAA
To: NTSB
Date: 10/5/1982
Response: FAA LETTER: THE AIRPLANE FLIGHT MANUAL (AFM) ONE-ENGINE INOPERATIVE PROCEDURES HAVE BEEN OR WILL BE REVISED TO INCLUDE RECOMMENDED APPROVED SPEEDS IN EXCESS OF V2 IF EITHER PERFORMANCE OR FLIGHT CHARACTERISTICS ARE NOT DEGRADED AT THE HIGHER SPEED. THE AFM OBSTACLE CLEARANCE PROCEDURES WILL RECOMMEND THAT FOR AN ENGINE FAILURE EXPERIENCED AT A SPEED BETWEEN V1 AND V2, THE AIRPLANE SHOULD BE ACCELERATED TO V2. IF THE FAILURE OCCURS AT A SPEED HIGHER THAN V2 BUT LOWER THAN A HIGHER APPROVED ALL ENGINE OPERATING SPEED, THE SPEED EXISTING WHEN THE FAILURE OCCURRED SHOULD BE MAINTAINED. IF FAILURE OCCURS AT A SPEED HIGHER THAN V2 PLUS THE APPROVES INCREMENT, THE AIRPLANE SHOULD BE SLOWED TO V2 PLUS THE APPROVED INCREMENT. IT SHOULD BE NOTED THAT THE SPEED V2 + 10 KNOTS WAS FOUND TO BE APPROPRIATE FOR ALL CASES OF OBSTACLE CLEARANCE PERFORMANCE. FOR EXAMPLE, THE BOEING MODEL 767 WAS APPROVED USING V2 + 15 KNOTS, AND THE GATES LEARET MODEL 35 WAS APPROVED USING V2 + 30 KNOTS. WHERE POSSIBLE, THE MANUFACTURERS AND USERS OF FLIGHT DIRECTOR SYSTEMS WILL MODIFY THE LOGIC OF THOSE SYSTEMS AT OUR REQUEST TO COMMAND SPEEDS IN ACCORDANCE WITH THE ABOVE DESCRIBED SCHEDULING. THE FLIGHT DIRECTOR PROCEDURES ARE ALSO INCLUDED IN THE AFM. ALTHOUGH ONLY THE SPEED V2 IS REQUIRED BY 14 CFR 25 TO BE SELECTED BY APPLICANTS, WE HAVE ENCOUNTERED NO RELUCTANCE ON THE PART OF MANUFACTURERS TO EXPAND THE PROCEDURES AS DESCRIBED. THEREFORE, WE FIND NO NECESSITY FOR RULE CHANGE, BUT HAVE IMPLEMENTED THE BOARD'S RECOMMENDATION AS CERTIFICATION POLICY. YOUR JUNE 8, 1982, LETTER SUGGESTED THAT FURTHER ACTION MAY BE REQUIRED ON THIS RECOMMENDATION PENDING THE RESULTS OF THE INVESTIGATION ON THE AIR FLIGHT MANUAL PROCEDURES, WHICH HAD BEEN REVISED IN SEPTEMBER 1980 TO INCORPORATE THE CONCEPT RECOMMENDED BY THE BOARD, WOULD HAVE BEEN APPROPRIATE DURING THIS INCIDENT HAD THE AIRPLANE REACHED V2 SPEED. REVISIONS TO THE AFM INCLUDING HIS INFORMATION ARE ENCLOSED. IN ADDITION, ALL DC-10 OPERATORS HAVE BEEN NOTIFIED OF THE RECOMMENDED PROCEDURES THROUGH THE MCDONNELL DOUGLASS COMPANY PUBLICATIONS "KNOW YOUR DC-10 AT ABOUT THE SAME TIME.

From: NTSB
To: FAA
Date: 6/7/1982
Response: A recent safety board investigation of an uncontained turbine disk failure incident involving air florida airlines dc-10-30cf, n101tv, on september 22, 1981, has caused the board to request information from the manufacturer regarding emergency procedures for takeoff. Since this informa-tion could be germane to recommendation a-79-105, which requests takeoff procedures revisions to increase stall margin during secondary emergencie this recommendation will remain classified as open-- acceptable action until evaluation of the manufacturer's response is completed.

From: FAA
To: NTSB
Date: 6/10/1981
Response: FAA LTR: THE FAA HAS COMPLETED AN EVALUATION OF A REPRESENTATIVE SAMPLE OF CURRENT JET TRANSPORT AIRCRAFT TO DETERMINE IF NTSB RECOMMENDATION A-79-105 COULD BE APPLIED AS A GENERAL POLICY FOR ALL AIRCRAFT. A CONCLUSION REACHED WAS THAT THE RECOMMENDATION MAY BE APPLICABLE TO SOME AIRCRAFT; HOWEVER, A GENERAL POLICY APPLICABLE TO ALL AIRCRAFT IS NOT POSSIBLE. IT WAS THEREFORE CONCLUDED THAT THE CHARACTER ISTICS OF INDIVIDUAL AIRCRAFT MODELS AND CONFIGURATIONS MUST BE EVALUATED TO DETERMINE WHETHER A CLIMB SPEED, AS RECOMMENDED BY NTSB, IS APPROPRIATE. THE FLIGHT STANDARD IZATION BOARD (FSB) REJECTED THE CONCEPT THAT COMPUTER FLIGHT DIRECTOR DATA SHOULD PRESENT OPTIMUM TAKEOFF-CLIMB AIRSPEED SCHEDULES IN THE EVENT OF SECONDARY EMERGENCIES. THE NEED TO COMPUTE SUCH INFORMATION FOR FLIGHT DIRECTOR DISPLAYS, CONSIDERING THE VARIABLES ASSOCIATED WITH A GIVEN TAKEOFF, IS NOT READILY APPARENT. IT WAS ALSO AGREED THAT AMENDING APPLICABLE REGULATIONS AND APPROVED FLIGHT MANUALS TO PRESCRIBE OPTIMUM TAKEOFF-CLIMB AIRSPEED SCHEDULES FOR USE DURING SECONDARY EMERGENCIES WOULD PROBABLY BE COUNTERPRODUCTIVE. OPTIMUM AIRSPEED SCHEDULES WOULD, OF NECESSITY, BE EXTENSIVE BECAUSE OF THE MANY VARIABLES ASSOCIATED WITH TAKEOFF CONDITIONS, COUPLED WITH THE MULTITUDE OF POSSIBLE SECONDARY EMERGENCIES. REFERENCE TO SUCH A SCHEDULE DURING AN EMERGENCY WOULD DIVERT CREW ATTENTION AT A CRITICAL TIME. UNDER SUCH CIRCUMSTANCES, WHAT IS NEEDED IS A SAFE AIRSPEED, V2; NOT AN OPTIMUM AIRSPEED.

From: NTSB
To: FAA
Date: 6/13/1980
Response: Since your response indicates positive action has been taken regarding this recommendation, we have classified the recommendation as open--acceptable action. We request that we be advised of progress regarding the regional review of the merits of increasing the stall margin for air carrier turbojet aircraft by maintaining whatever speed has been attained between v2 and v2 + 10 knots at the time of an engine failure. We would also appreciate receiving any information related to procedural changes in aircraft flight manuals or to revisions in training and checking procedures resulting from the regional reviews, or any information regarding flight director changes resulting from consideration of logic modification by the flight standardization policy board.

From: FAA
To: NTSB
Date: 3/20/1980
Response: FAA LTR: COMMENT ON A-79-105(A): THE FAA HAS INITIATED POSITIVE ACTION IN THIS REGARD. THE WESTERN REGION CONDUCTED AN EVALUATION OF A REPRESENTATIVE SAMPLE OF CURRENT JET TRANSPORT AIRCRAFT TO DETERMINE IF THE MAINTENANCE OF A SPEED BETWEEN V2, AND V2 + 10 KNOTS, IF ALREADY ATTAINED AT THE TIME OF ENGINE FAILURE, WOULD INCREASE THE STALL MARGIN WITHOUT INFRINGING ON TAKEOFF FLIGHTPATH REQUIREMENTS. A CONCLUSION REACHED WAS THAT THIS CONCEPT HAS MERIT FOR SELECTED AIRCRAFT, SUCH AS THE DC-10, IN CERTAIN FLIGHT CONDITIONS AND THE APPROPRIATE CHANGES ARE BEING INCORPORATED INTO THE AIRPLANE FLIGHT MANUALS. FAA REGIONS WITH CERTIFICATION RESPONSIBILITY FOR AIR CARRIER TURBOJET AIRCRAFT ARE BEING ASKED TO EVALUATE EACH MAKE AND MODEL OF AIRCRAFT WITHIN THEIR RESPECTIVE PURVIEW TO PROVIDE DATA PERTINENT TO THE RECOMMENDATION. COMMENT ON A-79-105(B): ASSUMING THE "OPTIMUM TAKEOFF CLIMB AIRSPEED SCHEDULES" REFERS TO THE UNIQUE SITUATION DURING A TAKEOFF-CLIMB OF MAINTAINING A SPEED BETWEEN V2 AND V2 + 10 KNOTS IF ALREADY ATTAINED AT THE TIME OF AN ENGINE FAILURE, THE FAA IS PRESENTLY ANALYZING THE DATA AND RECOMMENDATIONS OBTAINED FROM THE REGIONAL STUDIES REFERENCED IN RESPONSE TO (A). IF THE ANALYSIS REVEALS AN EQUIVALENT LEVEL OF SAFETY, THE APPROPRIATE DATA AND PROCEDURES ARE BEING INCORPORATED INTO THE RESPECTIVE AIRPLANE FLIGHT MANUALS (AFM). FURTHER, THIS DATA WILL BE ANALYZED AT THE SCHEDULED APRIL MEETING OF THE FAA'S FLIGHT STANDARDIZATION POLICY BOARD. COMMENT ON A-79-105(C): FLIGHT DIRECTOR SYSTEMS OF WIDEBODY AIRCRAFT ARE HIGHLY SOPHISTICATED SPECIAL PURPOSE COMPUTERS. THE DC-10 FLIGHT DIRECTOR MAY HAVE THE CAPACITY TO MEET THE INTENT OF THE RECOMMENDATION. TECHNICALLY, DIFFERENT DETAILS APPLY TO OTHER WIDEBODY AIRCRAFT, BUT THEY, TOO, MAY HAVE THE CAPACITY TO MEET THE REQUIREMENTS ENVISIONED BY THE RECOMMENDATION. BEFORE ISSUING RECOMMENDATIONS TO MANDATE A MODIFICATION OF FLIGHT DIRECTORS TO PROVIDE INFORMATION CORRESPONDING TO THE SPEED SCHEDULES DISCUSSED, OR TO PROVIDE IN THAT DESIGN FOR A WIDE VARIETY OF CONTINGENCIES, WE INTEND TO HAVE THE FLIGHT STANDARIZATION POLICY BOARD CONSIDER THESE ISSUES DURING THE FORTHCOMING APRIL MEETING.