The Federal Aviation Administration has known for at least six years that a loose screw in the cockpit window heaters of some Boeing planes has caused electrical arcing and fires. The agency has been promising for nearly as long to order airlines to fix the problem, but no order has yet been issued.
A timeline of key events:
— March 2002: The first report made to NASA's Aviation Safety Reporting System — a database that encourages airline employees and other to voluntarily report safety problems — of a Boeing 757 cockpit fire related to the window heater. The airline determines the cause was a loose screw.
— January 2004: A fire erupts near the cockpit window heat terminal of an Air Greenland 757. Four days later a cockpit fire in an American Airlines 757 prompts an emergency landing. Boeing tells the National Transportation Safety Board and the FAA the two incidents are similar to at least four previous incidents involving 747, 757, 767 and 777 planes.
— March 2004: Using windows removed from the American and Air Greenland planes, investigators determine a loose cross-threaded screw is causing electrical arcing; ASRS sends out the first of four safety alerts regarding window heater problems in the 757.
— May 2, 2004: An American 757 en route from Miami to Venezuela experiences a cockpit window fire. A cross-threaded screw is determined to be the cause. Boeing tells the NTSB a service bulletin for the 757 will be issued by September 2004.
— Mid-2004: Boeing begins making planes with a redesigned cockpit window that uses a pin-socket connector rather than a screw. The company says it will issue service bulletins recommending windows on existing 747, 757, 767 and 777 planes be replaced with the new design. The FAA says that once Boeing issues service bulletins, the agency will order airlines to inspect planes for the cross-threaded screw and replace damaged windows.
— January 2005: With service bulletins for 757s and other models still not issued, Boeing provides a schedule: March 10, 2005, for 757 and 767s bulletins; July 7, 2005, for the 747 bulletin. The FAA again promises to make the service bulletins mandatory after they are issued.
— February 2006: Service bulletins have not been issued. Boeing and the FAA tell the NTSB the cause of the delay is a "minor" disagreement over the wording of the bulletins.
— April 23, 2006: An American 757 diverts to John F. Kennedy International Airport in New York because of smoke in the cockpit. An inspection finds a short in the window heater due to a cross-threaded screw.
— June-August 2006: Boeing issues service bulletins for the 747, 757, and 777 models. A 767 service bulletin continues to be delayed due to the Boeing-FAA disagreement.
— Sept. 4, 2007: The NTSB sends the FAA a letter expressing concern that there is no safety order making the service bulletins mandatory. The board recommends the FAA approve Boeing's draft service bulletin for the 767 and order airlines to replace windows in the 747, 757, 767 and 777 planes with the new design.
Jan. 30, 2008: An American 757 suffers heavy cockpit smoke and a shattered window while over the Atlantic Ocean and makes an emergency landing in Palm Beach, Fla. Both pilots, three flight attendants and a passenger are treated for smoke inhalation.
March 13, 2008: The FAA proposes a safety order affecting 1,212 U.S.-registered planes. The order gives airlines a choice between the old window design plus regularly scheduled inspections or the new window design without inspections. It would apply to 757, 767 and 777 models, but not 747s.
April 2008: The NTSB recommends the proposed order be expanded to include 747s, and that airlines be required to install the new windows. Some airlines object to the FAA's proposal, saying the agency has misidentified the problem.
May 16, 2010: A cockpit fire aboard a United Airlines 757 prompts an emergency landing. FAA officials says they will expedite final approval of the proposed safety order.
Compiled by The Associated Press from reports filed to NASA's Aviation Safety Reporting System and National Transportation Safety Board records.