Airbus Industrie A300B4-605RAMERICAN AIRLINES
MIAMI, FL, USA · 2000-11-20·N14056
What happened
NTSB summary, verbatimAfter takeoff from Miami, the flight experienced a pressurization system malfunction, which the captain identified as the airplane depressurizing. The flight attendants and passengers complained of pain in their ears at that time. The flight crew placed the pressurization system into manual control, turned off the autopilot and autothrottle systems, and began a descent to return to Miami. During the return to Miami, several lavatory smoke alarms activated and the captain call light illuminated in the cabin; however, no evidence of fire or smoke was found. The flight crew did not complete the checklists for manual pressurization control and emergency landing during the return to Miami, both of which called for the airplane to be depressurized prior to landing. After landing and stopping on a taxiway, the captain also noticed an aft baggage compartment fire loop light illuminated, prompting him to evacuate the airplane. After the captain ordered the evacuation, the flight attendants attempted to open the doors. The doors would not open. The flight attendant/purser at the L1 (front left passenger) door continued to attempt to open the door, and the door explosively opened, ejecting the flight attendant/purser from the airplane to the ground, causing fatal injuries. The remainder of the doors opened and the airplane was evacuated. The emergency evacuation checklist did not call for the flight crew to check for depressurization of the airplane prior to commanding an evacuation. Post-accident examination of the airplane revealed that insulation blankets, which had been manufactured and replaced by the airplane operator's maintenance personnel, had not been properly secured per the airplane manufacturer's data. The blanket had migrated over to, and partially blocked, the forward and aft pressurization outflow valves, leading to the pressurization system malfunction. The forward outflow valve was found 3/8-open and the aft outflow valve was found fully closed. The lavatory smoke alarms were found to activate when subjected to abnormal pressure. There were no FAA technical standards for the lavatory smoke detectors. A sensor in the aft cargo compartment was found out of tolerance and also activated when subjected to abnormal pressure. The cabin doors were found to have no means for relieving pressure prior to opening the doors. The cabin altimeter in the cockpit did not have a mechanical stop in the negative direction, and under excessive pressure conditions, allowed the needle to move past the negative range into the high positive range. The aircraft manufacturer stated that when the pressurization system is in the manual mode, the outflow valves do not automatically open during landing and that a person cannot open a door if the airplane is pressurized above approximately 1.5 psi differential. As result of this investigation, the Safety Board previously issued 18 safety recommendations to the FAA.
Photographs
33the aircraft, and what the investigators foundPhotographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.
Probable cause
the Board's determinationThe failure of the flight crew to perform the cabin pressurization manual control abnormal checklist after experiencing a pressurization system malfunction and switching to manual pressurization control, and the failure of the flight crew to perform the emergency landing checklist prior to landing, resulting in the airplane having an excessive cabin pressure level after landing which led to a rapid decompression of the airplane when a flight attendant opened door and was ejected out of the airplane during emergency evacuation that was initiated by the captain. Contributing to the accident was the failure of operator maintenance personnel to ensure that insulation blankets around the forward and aft outflow valves were properly secured in accordance with airplane manufacturer's data, resulting in a malfunction of the pressurization system. Other contributing factors include the absence of FAA requirements that each emergency exit door has a system to relieve pressure or contain specific warnings (such as lights, placards, or other indications that clearly identify the danger of opening the emergency exit doors when the airplane is over pressurized); the absence of FAA technical specifications for lavatory ionization smoke detectors; the absence of a requirement in the airplane's ground/emergency evacuation checklist for the flight crew to ensure that the cabin differential pressure is zero pounds per square inch before signaling flight attendants to begin an emergency evacuation; and the absence of a mechanical stop in the negative direction on the cabin altimeter gauge.
Safety recommendations
18 issuedwhat changed because of this accidentTHE NTSB RECOMMENDS THAT THE FAA: REQUIRE THAT THE AIRBUS INDUSTRIE A300-600 OPERATING MANUAL CLEARLY STATE THAT AUTOMATIC DEPRESSURIZATION OF THE AIRPLANE UPON LANDING WILL NOT OCCUR WHEN THE PRESSURIZATION SYSTEM IS BEING OPERATED IN THE MANUAL MODE.
THE NTSB RECOMMENDS THAT THE FAA: REQUIRE THAT THE AIRBUS INDUSTRIE A300-600 OPERATING MANUAL CLEARLY STATE THAT THE RAM AIR SWITCH WILL NOT CONTROL THE OUTFLOW VALVES AND DEPRESSURIZE THE AIRPLANE WHEN THE PRESSURIZATION SYSTEM IS BEING OPERATED IN THE MANUAL MODE.
THE NTSB RECOMMENDS THAT THE FAA: REVIEW ALL AIRBUS INDUSTRIE A300-600 OPERATORS' MANUALS AND TRAINING PROGRAMS AND REQUIRE REVISIONS, IF NECESSARY, TO ENSURE THAT THEY CLEARLY INDICATE THAT AUTOMATIC DEPRESSURIZATION OF THE AIRPLANE UPON LANDING WILL NOT OCCUR WHEN THE PRESSURIZATION SYSTEM IS BEING OPERATED IN THE MANUAL MODE.
THE NTSB RECOMMENDS THAT THE FAA: REVIEW ALL AIRBUS INDUSTRIE A300-600 OPERATORS' OPERATING MANUALS AND TRAINING PROGRAMS AND REQUIRE REVISIONS, IF NECESSARY, TO ENSURE THAT THEY CLEARLY INDICATE THAT THE RAM AIR SWITCH WILL NOT CONTROL THE OUTFLOW VALVES AND DEPRESSURIZE THE AIRPLANE WHEN THE PRESSURIZATION SYSTEM IS BEING OPERATED IN THE MANUAL MODE.
THE NTSB RECOMMENDS THAT THE FAA: REQUIRE THAT THE AIRBUS INDUSTRIE A300-600 ON GROUND/EMERGENCY EVACUATION CHECKLIST DIRECT FLIGHT CREWS TO ENSURE THAT THE CABIN DIFFERENTIAL PRESSURE IS 0 POUNDS PER SQUARE INCH BEFORE SIGNALING FLIGHT ATTENDANTS TO BEGIN AN EMERGENCY EVACUATION.
THE NTSB RECOMMENDS THAT THE FAA: REVIEW ALL AIRBUS INDUSTRIE A300-600 OPERATORS' CHECKLISTS AND TRAINING PROGRAMS FOR EMERGENCY GROUND EVACUATION AND REQUIRE REVISIONS, IF NECESSARY, TO ENSURE THAT THEY DIRECT FLIGHT CREWS TO VERIFY THAT THE CABIN DIFFERENTIAL PRESSURE IS 0 POUNDS PER SQUARE INCH BEFORE SIGNALING FLIGHT ATTENDANTS TO BEGIN AN EMERGENCY EVACUATION.
THE NTSB RECOMMENDS THAT THE FAA: REVIEW ALL AIRBUS INDUSTRIE A300-600 OPERATORS' CHECKLISTS AND TRAINING PROGRAMS FOR PARKING AND REQUIRE REVISIONS, IF NECESSARY, TO ENSURE THAT THEY DIRECT FLIGHT CREWS TO VERIFY THAT THE CABIN DIFFERENTIAL PRESSURE IS 0 POUNDS PER SQUARE INCH BEFORE PERMITTING FLIGHT ATTENDANTS OR GATE AGENTS TO OPEN THE CABIN DOORS UPON ARRIVAL AT THE GATE.
The National Transportation Safety Board recommends that the Federal Aviation Administration: Require that all newly certificated transport-category airplanes have a system for each emergency exit door to relieve pressure so that they can only be opened on the ground after a safe differential pressure level is attained.
The National Transportation Safety Board recommends that the Federal Aviation Administration: For those transport-category airplane emergency exit doors that can be opened on the ground when the airplane is overpressurized, require air carriers to provide specific warnings near the emergency exit doors (such as lights, placards, or other indications) that clearly identify the danger of opening the emergency exit doors when the airplane is overpressurized.
The National Transportation Safety Board recommends that the Federal Aviation Administration: Review all air carriers’ flight and cabin crew training manuals and programs and require revisions, if necessary, to ensure that they contain information about the signs of an overpressurized airplane on the ground and the dangers of opening emergency exit doors while the airplane is overpressurized.
The National Transportation Safety Board recommends that the Federal Aviation Administration: Require that cabin crew training manuals and programs contain procedures to follow during an emergency evacuation when the airplane is overpressurized.
TO THE FEDERAL AVIATION ADMINISTRATION: Require that the cabin altimeter gauges on all Airbus Industrie A300 airplanes be modified to ensure that they will not give flight crews misleading indications about cabin altitude and pressure, particularly when the pressurization system is being operated in the manual mode. This could be accomplished either by the replacement of the gauge with a digital display, by the expansion of the values on the existing gauge design, or by other means.
TO THE FEDERAL AVIATION ADMINISTRATION: Conduct a survey of transport-category aircraft to determine which are equipped with cabin altimeters that are capable of displaying indications beyond the marked ranges of the gauge and require that the cabin altimeter gauges on those airplanes be modified to ensure that they will indicate the correct cabin altitude to the flight crew, particularly when the pressurization system is being operated in the manual mode. This could be accomplished either by the replacement of the gauge with a digital display, by the expansion of the values on the existing gauge design, or by other means.
TO THE FEDERAL AVIATION ADMINISTRATION: Require that all ionization-type smoke detectors (including lavatory smoke detectors) on newly manufactured transport-category aircraft adhere to the technical standards in Technical Standard Order C1c for cargo compartment smoke detectors.
TO THE FEDERAL AVIATION ADMINISTRATION: Require that, within 5 years, all ionization-type smoke detectors (including lavatory smoke detectors) on existing transport-category aircraft meet the same technical standards in Technical Standard Order C1c for cargo compartment smoke detectors.
TO THE FEDERAL AVIATION ADMINISTRATION: Until all existing aircraft have been retrofitted with ionization-type smoke detectors that are technical standard order (TSO)-compliant, require that the operating manuals of all transport-category aircraft, including the Airbus Industrie A300, that are equipped with ionization-type smoke detectors (including lavatory smoke detectors) that are not TSO-compliant state that overpressure conditions may lead to false alarms from those detectors.
TO THE FEDERAL AVIATION ADMINISTRATION: Require that all operators of Airbus Industrie A300 airplanes eliminate the CAPT CALL light and the green keypad illuminations from the lavatory smoke detector alarm function.
TO THE FEDERAL AVIATION ADMINISTRATION: Require that, on all future Airbus Industrie A300 airplanes, the CAPT CALL light and the green keypad illuminations are not included in the lavatory smoke detector alarm function.
Sequence of events
5 timed eventsfrom the FDR factual report · claude-sonnet-5- 1149Departurep.1Flight originated from Miami, Florida
- 12:17:43Landingp.2Aircraft landed
- 12:18:37Landing rollp.2Vertical, lateral and longitudinal accelerations data were consistent with the aircraft coming to a complete stop (approximately 54 seconds after landing)
- 1222Emergency evacuationp.1A flight attendant received fatal injuries during an emergency evacuation after the flight returned to Miami
- 12:21:28Post-landing/evacuationp.2FDR stopped recording data (approximately 2 minutes and 51 seconds after aircraft came to complete stop)
NTSB analysis
from the final reportAfter takeoff from Miami, the flight experienced a pressurization system malfunction, which the captain identified as the airplane depressurizing. The flight attendants and passengers complained of pain in their ears at that time. The flight crew placed the pressurization system into manual control, turned off the autopilot and autothrottle systems, and began a descent to return to Miami. During the return to Miami, several lavatory smoke alarms activated and the captain call light illuminated in the cabin; however, no evidence of fire or smoke was found. The flight crew did not complete the checklists for manual pressurization control and emergency landing during the return to Miami, both of which called for the airplane to be depressurized prior to landing. After landing and stopping on a taxiway, the captain also noticed an aft baggage compartment fire loop light illuminated, prompting him to evacuate the airplane. After the captain ordered the evacuation, the flight attendants attempted to open the doors. The doors would not open. The flight attendant/purser at the L1 (front left passenger) door continued to attempt to open the door, and the door explosively opened, ejecting the flight attendant/purser from the airplane to the ground, causing fatal injuries. The remainder of the doors opened and the airplane was evacuated. The emergency evacuation checklist did not call for the flight crew to check for depressurization of the airplane prior to commanding an evacuation. Post-accident examination of the airplane revealed that insulation blankets, which had been manufactured and replaced by the airplane operator's maintenance personnel, had not been properly secured per the airplane manufacturer's data. The blanket had migrated over to, and partially blocked, the forward and aft pressurization outflow valves, leading to the pressurization system malfunction. The forward outflow valve was found 3/8-open and the aft outflow valve was found fully closed. The lavatory smoke alarms were found to activate when subjected to abnormal pressure. There were no FAA technical standards for the lavatory smoke detectors. A sensor in the aft cargo compartment was found out of tolerance and also activated when subjected to abnormal pressure. The cabin doors were found to have no means for relieving pressure prior to opening the doors. The cabin altimeter in the cockpit did not have a mechanical stop in the negative direction, and under excessive pressure conditions, allowed the needle to move past the negative range into the high positive range. The aircraft manufacturer stated that when the pressurization system is in the manual mode, the outflow valves do not automatically open during landing and that a person cannot open a door if the airplane is pressurized above approximately 1.5 psi differential. As result of this investigation, the Safety Board previously issued 18 safety recommendations to the FAA.