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Safety Recommendation Details

Safety Recommendation A-91-120
Details
Synopsis: ON FEBRUARY 1, 1991, AT 1807 PACIFIC STANDARD TIME, USAIR FLIGHT 1493 (USA1493), N388US, A BOEING 737-300 (B-737), COLLIDED WITH SKYWEST FLIGHT 5569(SKW5569), N683A, V, A FAIRCHILD METROLINER (SA-227-AC), WHILE USA1493 WAS LANDING ON RUNWAY 24 LEFT AT LOS ANGELES INTERNATIONAL AIRPORT (LAX), LOS ANGLES, CALIFORNIA. SKW5569 WAS POSITIONED ON THE SAME RUNWAY, AT INTERSECTION 45, AWAITING CLEARANCE FOR TAKEOFF. AS A RESULT OF THE COLLISION, BOTH AIRPLANES WERE DESTROYED. ALL 10 PASSENGERS AND 2 CREWMEMBERS ABOARD THE METROLINER AND 20 PASSENGERS AND 2 CREWMEMBERS ABOARD THE B-737 WERE FATALLY INJURED.
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: CONDUCT A DIRECTED SAFETY INVESTIGATION OF THE SUNSTRAND MODEL AV-557 CVR TO DETERMINE THE NECESSARY MODIFICATIONS TO ENSURE THAT THE SWITCHING MECHANISM IN THE UNIT IS ABLE TO WITHSTAND RECORDING TAPE ANOMALIES AND VARIATIONS IN TAPE OPACITY THAT CAN BE EXPECTED TO APPEAR DURING THE NORMAL SERVICE LIFE OF THE TAPE.
Original recommendation transmittal letter: PDF
Overall Status: Closed--No Longer Applicable
Mode: Aviation
Location: LOS ANGELES, CA, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA91MA018AB
Accident Reports: Runway Collision of USAIR Flight 1493, Boeing 737 and Skywest Flight 5569 Fairchild Metroliner
Report #: AAR-91-08
Accident Date: 2/1/1991
Issue Date: 12/3/1991
Date Closed: 2/16/1994
Addressee(s) and Addressee Status: FAA (Closed--No Longer Applicable)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 2/16/1994
Response: THE BOARD NOTES THAT THE FAA AND SUNDSTRAND DATA CONTROL (SDC) CONDUCTED A REVIEW OF THE SUNDSTRAND MODEL AV-557 CVR AND CONCLUDED THAT THE CVR WILL PERFORM ITS INTENDED FUNCTION IF THE UNIT IS MAINTAINED PROPERLY. HOWEVER, THE BOARD CONCLUDES THAT THE DESIGN OF THE CURRENT SWITCHING MECHANISM, WHICH RELIES SOLELY ON THE OPACITY OF THE RECORDING TAPE, IS DEFICIENT BECAUSE THE MECHANISM WILL TRIGGER ON MINOR TAPE DEFECTS AS WELL AS ON THE INTENDED END-OF-TAPE WINDOW. THE BOARD FURTHER BELIEVES THAT THESE MINOR DEFECTS CAN OCCUR IN THE MANUFACTURING PROCESS OR DURING HANDLING AND ARE NOT ALWAYS A RESULT OF WEAR-RELATED TAPE DETERIORATION. SUNDSTRAND HAS INFORMED THE BOARD THAT IT HAS INITIATED ACTION TO IMPROVE THE CHARACTERISTICS OF ITS SWITCHING MECHANISM AS REQUESTED IN RECOMMENDATION A-91-120. ALTHOUGH BOARD IS DISAPPOINTED BY THE FAA'S FAILURE TO ADEQUATELY ADDRESS THIS RECOMMENDATION, BASED ON SUNDSTRAND'S COMMITMENT TO CORRECT THE DEFICIENCY, RECOMMENDATION A-91-120 HAS BEEN CLASSIFIED "CLOSED--NO LONGER APPLICABLE."

From: NTSB
To: FAA
Date: 4/8/1993
Response: THE BOARD NOTES THAT THE FAA BELIEVES THAT THE SUNSTRAND MODEL AV-557 CVR UNIT WILL PERFORM ITS INTENDED FUNCTION IF THE UNIT IS MAINTAINED PROPERLY & THE TAPE IS REPLACED PERIODICALLY. FURTHERMORE, THE FAA HAS REQUESTED THAT SUNDSTRAND DATA CONTROL ISSUE A SERVICE BULLETIN INCORPORATING A MORE STRINGENT REQUIREMENT TO PERIODICALLY REPLACE THE CVR TAPE. PENDING FURTHER INFO, RECOMMENDATION A-91-120 IS CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

From: FAA
To: NTSB
Date: 12/11/1992
Response: THE FAA AND SUNDSTRAND DATA CONTROL (SDC) CONDUCTED A REVIEW OF THE SUNDSTRAND MODEL AV-557 COCKPIT VOICE RECORDER (CFR) AND CONCLUDED THAT THE CVR WILL PERFORM ITS INTENDED FUNCTION IF THE UNIT IS MAINTAINED PROPERLY, INCLUDING THE SWITCHING MECHANISM AND THE PERIODIC TAPE REPLACEMENT. THE FAA AGREES WITH THE BOARD THAT MORE STRIGENT TAPE REPLACEMENT IS NEEDED. CONSEQUENTLY, SDC ISSUED SERVICE BULLETIN NO. 124 INCORPORATING A REQUIREMENT TO REPLACE THE MYLER TAPE EVERY 6,000 OPERATING HOURS.

From: FAA
To: NTSB
Date: 3/2/1992
Response: The FAA and Sundstrand Data Control (SDC) have reviewed the service life histroy of the Sundstrand Model AV-557 cockpit voice recorder (CVR) installed on board USAir Flight 1493. That CVR unit was originally shipped by SDC to the operator in October 1989. Subsequent maintenance records do not indicate that the Mylar tape, which had approximately 8,000 to 12,000 hours, was replaced by the operator. The FAA, therefore, concludes that the variations in the tape opacity were caused by excessive wear and taht the pinholes identified in the tape were the result of minute particles or shavings caught in the tape transport mechanism. The FAA believes that the CVR swithcing mechanism will perform its intended function if the unit is maintained properly and when the tape is replaced periodically. The FAA has requested SDC to issue a service bulletin to the Sundstrand Model AV-557 Maintenance Manual incorporating a more stringent requirement to periodically replace the CVR tape. The FAA will review the revised service bulletin to determine what, if any, further action is required. I will keep the Board apprised of the FAA's progress on this safety recommendation.