Date: 11/10/2008
By TIM KLASS
Associated Press Writer
SEATTLE (AP) _ The Federal Aviation Administration has toughened a requirement that Boeing 737 pilots be reminded not to ignore a cabin pressure warning horn, ordering preflight briefings as well as changes in manuals.
The airworthiness directive, issued Monday and effective Nov. 25, stems from a crash in which 121 people died on Aug. 14, 2005, when a Helios Airways 737-300 slammed into a hillside north of Athens, Greece.
Greek investigators determined that the pilots had lost consciousness because of a cabin pressure failure shortly after takeoff on a flight from Nicosia, Cyprus, and that the plane kept going on autopilot for two hours until it ran out of fuel.
Authorities say the cabin pressure control settings had been operated improperly and that an alarm went unheeded. Last Tuesday the attorney general of Cyprus said five people would face criminal charges for the crash.
The FAA’s order applies to all Boeing 737s, the world’s best-selling commercial jet with more than 6,000 orders since the model was launched in 1965 and 5,397 in use worldwide, and takes effect in 120 days. Public notice and comment requirements were waived “because an unsafe condition exists that requires the immediate adoption” of the directive, according to the notice.
Changes in the manuals must be made by each airline. The process is complex, varying by aircraft as well as the nature of the change, and new wording must be validated before it can take effect, FAA spokesman Les Dorr said.
FAA directives typically are reissued by civil aviation authorities in other countries.
Chicago-based Boeing Co. and FAA representatives said the cockpit warning horn serves a dual purpose. On the ground it indicates something is wrong with the plane’s pre-takeoff configuration, such as the setting of the wing flaps. In the air it means a loss of cabin pressure, which can cause pilots to lose consciousness if they don’t immediately put on oxygen masks.
The FAA directed on July 7, 2006, that flight manuals be changed to remind pilots to pay heed to the warning horn after takeoff, but “we have received continuing reports of in-service events involving failure of the flight crew to recognize and react property to valid cabin altitude (air pressure) warning horns,” according to the latest directive.
It was not immediately clear which airlines were involved in the reports of pilots ignoring the horn, when the problems occurred or whether any U.S. carriers were involved.
Such problems in other countries typically are reported to civil aviation authorities who then notify the manufacturer, in this case Boeing, which in turn alerts the FAA, Dorr said.
Before the Helios crash, Boeing was alerted to “some cases where flight crews were getting confused” about the alarm horn and advised airlines “to do a little crew training on that,” Boeing spokeswoman Liz Verdier said.
After the FAA’s initial directive, which largely incorporated Boeing’s advisory note, the manufacturer began working on a change in the cockpit and flight deck design to incorporate a warning light that will provide a second indication of cabin pressure loss when the horn sounds, Verdier said.
“Within the next month or so,” she said, Boeing expects to have the change ready to incorporate into production of current models, the 737-700, -800 and 900, followed by production of retrofitting kits for earlier models a few months after that.
The FAA may propose further action to “address the unsafe condition” once the warning light kits are available, according to the airworthiness directive.
Copyright 2008 The Associated Press.