Doors prove deadly if opened when cabin remains pressurized
Exit doors intended to save lives during an emergency evacuation need to be designed so they do not inadvertently kill or injure door operators if the cabin remains pressurized. The doors need to feature a vent or gate so that they can be opened safely even if the cabin pressurization system is malfunctioning.An August 2 recommendation from the National Transportation Safety Board (NTSB) cited the Nov. 20, 2000, accident in which flight attendant/purser Jose Chiu was hurled more than 40 feet out of the left main door when it suddenly blew open as he attempted to open it during an emergency evacuation of the American Airlines [AMR] twinjet at Miami. The accident involved an Airbus A300-605R with 133 passengers and crew on board. Chiu, who by one account was thrown beyond the wingtip, was killed on impact with the concrete tarmac.
A similar case occurred almost a year later, on October 20, 2001, involving an A300-605R operated by TunisAir. While an air stair was being positioned for normal deplaning, engine bleed air kept the cabin pressurized. Excessive cabin air caused the door to burst open. The flight attendant attempting to open the door was ejected, sustaining serious injuries. A second flight attendant at the doorway also ejected was killed.
In the case of the American Airlines fatality, the airplane took off from Miami for a planned flight to Haiti. Climbing through 16,000 feet,
the ECAM [electronic centralized aircraft monitoring] display indicated that the forward cabin outflow valve was fully open (actually, according to sources, insulation blankets had clogged the valve). The aircraft pressurization system may be described as akin to a leaky balloon. Bleed air from the engines pressurizes the cabin to an artificial altitude of 8,000 feet, and one or more outflow valves regulates the discharge of cabin air to maintain a constant "cabin altitude" and to prevent sudden pressure changes during climb/descent (which passengers may notice by a popping of the ears).
Just 11 minutes after departure, and with warnings sounding from lavatory smoke detectors and a warning light indicating a possible fire in the belly hold (both false, as it turned out) the captain determined to return to Miami. He ordered an emergency evacuation upon landing.The cabin pressure actually increased after landing, and the panoply of warnings persisted. With the cabin pressurized, none of the emergency exit doors could be opened. That is, until Door 1L suddenly blew open, ejecting flight attendant Chiu. Cabin overpressure was relieved, and all other doors with handles in the open position opened and their escape slides deployed.Given the likelihood of future failures to outflow valves, the NTSB believes this type of overpressurization event "could occur again."