NTSB · Safety Recommendation
Safety Recommendation A-94-039
Recommendation
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ESTABLISH CERTIFICATION REQUIREMENTS FOR FLIGHT CONTROL HANDLING CHARACTERISTICS, SUCH AS STICK FORCE PER G LIMITS, AND REQUIRE FLIGHT DEMONSTRATIONS TO ENSURE THAT PILOTS CAN SAFELY RECOVER FROM ABRUPT HIGH ALTITUDE, HIGH SPEED UPSETS IN TRANSPORT-CATEGORY AIRPLANES.
Safety Issue and Context
ON DECEMBER 7, 1992, ABOUT 1036 COORDINATED UNIVERSAL TIME, A MCDONNEL DOUGLAS MD-11, TIAWAN REGISTRATION B-150, CHINA AIRLINES, FLIGHT CI-012, ENCOUNTERED MODERATE TURBULENCE AT FLIGHT LEVEL 330. THE AIRPLANE SUBSEQUENTLY DEPARTED CONTROLLED FLIGHT AND SUSTAINED DAMAGED TO THE LEFT AND RIGHT OUTBOARD ELEVATOR SKIN ASSEMBLIES, PORTIONS OF WHICH SEPARATED FROM THE AIRPLANE. THE AIRPLANE WAS OPERATING UNDER THE PROVISIONS OF TITLE 14, CODE OF FEDERAL REGULATIONS, PART 129, AS A SCHEDULED PASSENGER FLIGHT FROM TAIPEI, TAIWAN, TO ANCHORAGE, ALASKA. THERE WERE 246 PASSENGERS, 3 FLIGHTCREW MEMBERS, 2 ADDITIONAL CREWMEMBERS AND 14 CABINCREW MEMBERS ON BOARD, NONE OF WHOM REPORTED ANY INJURIES.
THE AIRPLANE CONTINUED ON AND LANDED UNEVENTFULLY AT ANCHORAGE, ALASKA.
Response History
December 8, 1998 · NTSB Correspondence · FAA
THE BOARD NOTES THAT THE FAA HAS ISSUED A REVISED ADVISORY CIRCULAR (AC) 25-7A, WHICH PROVIDES PROCEDURES AND CRITERIA TO EVALUATE AN AIRCRAFT'S SUSCEPTIBILITY TO PILOT-INDUCED OSCILLATIONS (PIO'S, ALSO REFERRED TO AS AIRCRAFT-PILOT COUPLING, OR A-PC) IN A VARIETY OF FLIGHT REGIMES AND MANEUVERS, WITH SPECIAL EMPHASIS ON AIRCRAFT WITH AUGMENTED OR FLY-BY-WIRE CONTROL SYSTEMS. THE BOARD ALSO NOTES THAT THE FAA IS WORKING WITH THE EUROPEAN JOINT AIRWORTHINESS AUTHORITIES (JAA) FLIGHT STUDY GROUP AND CALSPAN TO DEVELOP ADDITIONAL HARMONIZED GUIDANCE MATERIAL, DATA, AND FLIGHTCREW TRAINING TECHNIQUES RELATING TO PIO/A-PC.
THE BOARD APPRECIATES THE FAA'S ACTION TO DATE AND URGES THE FAA TO MOVE QUICKLY ON THE DEVELOPMENT OF THE ADDITIONAL GUIDANCE MATERIAL, DATA, AND FLIGHTCREW TRAINING TECHNIQUES AS OUTLINED ABOVE. BASED ON THE FAA'S ACTION, THE SAFETY BOARD HAS CLASSIFIED A-94-39 "CLOSED--ACCEPTABLE ACTION."
August 6, 1998 · Recipient Response · FAA
ON 6/9/95, THE FAA PUBLISHED A FINAL RULE TO ADD A REQUIREMENT TO 14 CFR PART 25 RELATING TO ALLOWABLE STICK FORCES IN MANEUVERING FLIGHT. A COPY OF THE FINAL RULE WAS PROVIDED TO THE BOARD ON 9/18/96. ON 3/31/98, THE FAA PUBLISHED AC 25-7A, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES, TO PROVIDE GUIDANCE IN COMPLYING WITH THE NEW REQUIREMENTS OF 14 CFR PART 25. THE AC PROVIDES UPDATED FLIGHT TEST GUIDANCE CONCERNING CERTIFICATION REQUIREMENTS FOR CONTROL FORCES AND STICK FORCE CHARACTERISTICS AS THEY RELATE TO PILOT OVERCONTROL/OVERSTRESS OF TRANSPORT-CATEGORY AIRPLANES. I HAVE ENCLOSED A COPY OF THE AC FOR THE BOARD'S INFORMATION.
I CONSIDER THE FAA'S ACTION TO BE COMPLETED, AND I PLAN NO FURTHER ACTION.
December 12, 1997 · Recipient Response · FAA
THE FAA DRAFTED, AND RELEASED FOR PUBLIC COMMENT, A REVISION TO ADVISORY CIRCULAR (AC) 25-7, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES. THE DRAFT REVISION PROVIDED PROCEDURES TO EVALUATE AN AIRCRAFT'S SUSCEPTIBILITY TO PILOT-INDUCED OSCILLATIONS IN CRUISE CONDITIONS. SINCE THE TIME THE DRAFT WAS RELEASED FOR COMMENT, AIRCRAFT-PILOT COUPLING EVENTS HAVE BEEN OCCURRING IN THE LOW-SPEED TAKEOFF AND LANDING FLIGHT REGIMES. IN ADDITION, AIRCRAFT-PILOT COUPLING EVENTS HAVE BEEN LINKED TO AIRCRAFT WITH AUGMENTED AND FLY-BY-WIRE CONTROL SYSTEMS.
BASED ON THESE FACTS AND THE EXTENSIVE COMMENTS RECEIVED ON THE DRAFT FROM BOTH INDUSTRY AND FOREIGN REGULATORY AUTHORITIES, THE FAA HAS EXPANDED THE DRAFT SIGNIFICANTLY. THE NEW DRAFT WILL INCLUDE FLIGHT TEST PROCEDURES AND CRITERIA FOR ALL FLIGHT REGIMES, AND SPECIAL EMPHASIS WILL BE PLACED ON AIRCRAFT WITH AUGMENTED OR FLY-BY-WIRE CONTROL SYSTEMS. THE EXPANDED DRAFT WILL BE HARMONIZED WITH THE FOREIGN REGULATORY AUTHORITIES AND CIRCULATED TO THE INDUSTRY FOR COMMENT. IT IS ESTIMATED THAT THE REVISION TO AC 25-7 WILL BE ISSUED BY DECEMBER 1999.
IN THE MEANTIME, THE FLIGHT TEST PROCEDURES AND CRITERIA IN SPECIAL CONDITION F-1 OF THE MD-11 CERTIFICATION DOCUMENTATION WILL BE USED IN CERTIFICATION PROJECTS FOR TRANSPORT CATEGORY AIRCRAFT. SPECIAL CONDITION F-1 WAS USED IN THE CERTIFICATION OF THE MD-11 TO ENSURE THAT MODIFICATIONS TO THE AIRPLANE'S LONGITUDINAL STABILITY AUGMENTATION SYSTEM CORRECTED PREVIOUS TENDENCIES FOR AIRCRAFT-PILOT COUPLING DURING HIGH-ALTITUDE, HIGH-SPEED CRUISE UPSETS. I WILL KEEP THE BOARD APPRISED OF THE FAA'S PROGRESS ON THIS RECOMMENDATION.
July 31, 1997 · NTSB Correspondence · FAA
THE SAFETY BOARD LOOKS FORWARD TO RECEIVING A COPY OF THE REVISED AC, AND CLASSIFIES A-94-39 AS "OPEN--ACCEPTABLE RESPONSE," PENDING THE BOARD'S RECEIPT AND REVIEW OF THE REVISION.
July 3, 1997 · Recipient Response · FAA
ON JUNE 9, 1995, THE FAA REVISED 14 CFR PART 25, RELATING TO ALLOWABLE STICK FORCES IN MANEUVERING FLIGHT, AND IT REVISED ADVISORY CIRCULAR (AC) 25-7, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES, TO PROVIDE GUIDANCE IN COMPLYING WITH THE NEW REQUIREMENTS OF 14 CFR PART 25. IT IS CURRENTLY REVISING AC 25-7 ON THE SUSCEPTIBILITY TO HIGH ALTITUDE, PILOT-INDUCED OSCILLATIONS TO ADDRESS THIS RECOMMENDATION. IT PLANS TO PUBLISH THE REVISION TO AC 25-7 BY DECEMBER 1997 AND WILL PROVIDE THE BOARD WITH A COPY OF THE REVISED AC.
November 7, 1995 · NTSB Correspondence · FAA
THE BOARD HAS REVIEWED THE REQUIREMENT ADDED TO 14 CFR PART 25 REGARDING ALLOWABLE MANEUVERING STICK FORCES. THE BOARD ALSO NOTES THAT THE FAA IS REVISING ADVISORY CIRCURLAR 25-7 TO ADDRESS A-94-39. THE BOARD IS PLEASED THAT THE FAA IS WORKING WITH INDUSTRY TO ESTABLISH HIGH-ALTITUDE HANDLING CHARACTERISTICS IN TRANSPORT-CATEGORY AIRPLANES & BELIEVES THAT SUCH REQUIREMENTS WILL HELP PREVENT FUTURE OCCURRENCES OF HIGH-ALTITUDE, HIGH-SPEED PILOT OVER-CONTROL/OVER-STRESS UPSETS, PARTICULARLY WITH THE MD-11. THEREFORE, PENDING REVIEW OF AC 25-7, A-94-39 IS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."
September 18, 1995 · Recipient Response · FAA
ON 6/9/95, THE FAA PUBLISHED A FINAL RULE TO ADD A REQUIREMENT TO 14 CFR PART 25 RELATING TO ALLOWABLE STICK FORCES IN MANEUVERING FLIGHT. ADDITIONALLY, THE FAA PUBLISHED REVISIONS TO ADVISORY CIRCULAR 25-7, FLIGHT TEST GUIDE FOR CERTIFICATION OF TRANSPORT CATEGORY AIRPLANES, TO PROVIDE GUIDANC3E IN COMPLYING WITH THE NEW REQUIREMENTS OF 14 CFR PART 25. THE PROPOSED REVISIONS TO AC 2507 WERE PUBLISHED IN THE EDERAL REGISTER FOR COMMENT. THE FAA HAS DECIDED TO INITIATE FURTHER REVISIONS TO AC 25-7 TO ADDRESS THE ISSUE OF SUSCEPTIBILITY TO HIGH ALTITUDE, PILOT-INDUCED OSCILLATIONS.
THE FAA IS WORKING WITH AVIATION INDUSTRY REGARDING AN APPROPRIATE WAY TO EVALUATE THIS CHARACTERISTIC IN TRANSPORT CATEGORY AIRPLANES & WILL INCLUDE THIS INFO IN THE REVISED AC. IT IS ANTICIPATED THAT THE REVISED AC WILL BE PUBLISHED IN THE FEDERAL REGISTER FOR COMMENT BY THE END OF 1995. I BELIEVE THAT THE REVISION TO 14 CFR PART 25 & THE REVISED AC WHEN ISSUED WILLL COMPLETELY ADDRESS THIS RECOMMENDATION. I WILL PROVIDE THE BOARD WITH A COPY OF THE AC AS SOON AS IT IS ISSUED.
August 16, 1994 · NTSB Correspondence · FAA
THE BOARD LOOKS FORWARD TO REVIEWING THE FAA'S NOTICE OF PROPOSED RULEMAKING & ADVISORY CIRCULAR FLIGHT TEST GUIDANCE CONCERNING CERTIFICATION REQUIREMENTS FOR CONTROL FORCES & STICK FORCE CHARACTERISTICS AS THEY RELATE TO PILOT OVERCONTROL/OVERSTRESS OF TRANSPORT-CATEGORY AIRPLANES. THE BOARD BELIEVES THAT SUCH REQUIREMENTS & GUIDANCE WILL HELP TO PREVENT FUTURE INSTANCES OF PILOT OVERCONTROL/OVERSTRESS OF TRANSPORT-CATEGORY AIRPLANES, PARTICULARLY DURING HIGH/ALTITUDE, HIGH-SPEED UPSETS SUCH AS THOSE EXPERIENCED BY THE MD-11. THEREFORE, PENDING REVIEW OF THE NPRM, SUBSEQUENT RULEMAKING, & AC FLIGHT TEST GUIDANCE, THE BOARD CLASSIFIES A-94-039 "OPEN--ACCEPTABLE RESPONSE."
May 26, 1994 · Recipient Response · FAA
THE FAA SHARES THE BOARD'S CONCERN THAT AIRPLANES DESIGNED TO OPERATE WITH REDUCED STATIC LONGTUDINAL STABILITY MARGINS MAY BE SUSCEPTIBLE TO PILOT OVERCONTROL IN HIGH ALTITUDE, HIGH SPEED FLIGHT CONDITIONS. THE FAA HAS WORKED WITH MEMBERS OF THE AEROSPACE INDUSTRY & THE EUROPEAN JOINT AVIATION AUTHORITIES, IN CONJUNCTION WITH THE AVIATION RULEMAKING ADVISORY COMMITTEE, IN THE DEVELOPMENT OF STICK FORCE PER G CERTIFICATION CRITERIA. THESE CRITERIA ARE PRESENTED IN A DRAFT NOTICE OF PROPOSED RULEMAKING ENTITLED "REVISION OF CERTAIN FLIGHT AIRWORTHINESS REQUIREMENTS TO HARMONIZE WITH EUROPEAN AIRWORTHINESS STANDARDS FOR TRANSPORT CATEGORY AIRPLANES.