The Federal Aviation Administration (FAA) has mandated enhanced safety equipment and emergency procedures to prevent dangerous pressurization problems on more than 700 older Boeing 737 aircraft.
The FAA final rule, released on Friday, aims to help cockpit crews of aircraft operated by US carriers swiftly identify and react to in-flight malfunctions that can mean a loss of cabin pressure depriving pilots of oxygen. The directive appears to be the final step in implementing various lessons learned from the much-publicized 2005 crash of a Helios Airways Boeing 737 after its pilots passed out from lack of oxygen.
The agency ordered installation of warning lights on some planes, specifically intended to alert pilots of hazardous pressurization problems that could prevent adequate oxygen from circulating inside the fuselage. The lights replace warning horns, which have confused some pilots because those same aural devices also serve to alert crews about improper configuration of flight-control surfaces prior to takeoff.
In the past, FAA officials disclosed more than two dozen instances of 737 pilots disregarded the horns while airborne, often assuming they were malfunctioning. The agency said the final rule was intended to prevent "failure of flight crews to recognize and react properly to a valid cabin altitude warning horn, which could result in incapacitation" and loss of aircraft control.
Investigators determined that's what happened to the pilots of the Helios Airways 737, who failed to detect a serious pressurization-system failure, while flying from Larnaca, Cyprus, to Prague, with a planned stop in Athens. The problem stemmed from improperly set cabin-pressure controls.
Boeing issued a nonbinding service bulletin a year ago dealing with installation of such lights, and is working on at least one more.