NTSB Probing Smoke in Boeing Cockpits

Air Safety Week, Feb 11, 2008

The National Transportation Safety Board is investigating an incident that occurred on January 30 in which an American Airlines B757-200, Flight 1738, en route from San Juan, Puerto Rico to Philadelphia, diverted to West Palm Beach, FL, making an emergency landing after the cockpit filled with smoke.

Of the 139 passengers and seven crewmembers, several were transported to the hospital for smoke inhalation and released.

According to reports from the crew, while at cruise altitude over the Atlantic Ocean, smoke began emanating from the window heating system connected to the first officer's windshield. The crew donned oxygen masks and smoke goggles. During the descent, the inner pane of the first officer's windshield shattered, but the 757 landed without incident, and no fire was reported.

The digital flight data recorder (DFDR) was downloaded and sent to the NTSB laboratories in Washington. The affected windshield, which remained in one piece, and the heating unit were removed from the aircraft and will undergo a detailed analysis.

While the cause of this particular incident is unknown and remains under investigation, the Safety Board is aware of five events between 2004 and 2006 in which smoke, and in some cases fire, were reported to have originated from window heating systems in B-757 aircraft.

And the Jan. 30 incident involving AA Flight 1738 was followed by an event involving a Boeing 767. On Feb. 4, United Airlines Flight 871, traveling from Washington, DC to San Francisco, with 226 people, including 11 crewmembers, made an emergency landing at Kansas City International Airport after reports of smoke in the cabin. There were no injuries. Crewmembers were unable to immediately determine where the smell came from.

In September 2007, the NTSB issued two safety recommendations to the Federal Aviation Administration (FAA) involving redesigned window heating systems for Boeing 747, 757, 767, and 777 series aircraft.

Those safety recommendations have not been implemented by the FAA, but a spokesman says Boeing in recent week issued a service bulletin addressing the air safety issue. He also said the FAA expects to issue an airworthiness directive concerning window heating systems on Boeing jetliners in the next few months.

The Safety Board is "very concerned" that airworthiness directives originally scheduled to be issued as early as September 2004 still have not been issued. "The Board considers any kind of fire and/or smoke in the cockpit to be a serious issue that could affect other aircraft systems, lead to a loss of visibility, provide a distraction, or incapacitate the crew and possibly lead to an accident."

Specifically, the NTSB recommends that the FAA mandate the installation of redesigned windshield heat terminal blocks on Boeing 767s and issue airworthiness directives to replace the windshield heat terminal blocks on all Boeing 747, 757, 767, and 777 airplanes in accordance with Boeing service bulletins.

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