Tuesday, October 21, 2008
Dealing with electrical failure while trying to maintain aircraft control
|The NTSB doesn’t just investigate accidents; it also routinely examines incidents to determine whether they expose an underlying safety problem, which, if not addressed, could set the stage for future accidents. Recently, it examined an incident involving an Airbus A320 operated by United Airlines. This led to the discovery that there had been at least 49 similar incidents in the United States and the United Kingdom. In response to its own investigation, the NTSB issued a safety recommendation, hoping to encourage FAA action.|
The NTSB doesn’t just investigate accidents; it also routinely examines incidents to determine whether they expose an underlying safety problem, which, if not addressed, could set the stage for future accidents. Recently, it examined an incident involving an Airbus A320 operated by United Airlines. This led to the discovery that there had been at least 49 similar incidents in the United States and the United Kingdom. In response to its own investigation, the NTSB issued a safety recommendation, hoping to encourage FAA action.
Regardless of the FAA’s reaction, the recommendation should raise awareness of a broader issue for pilots flying technologically advanced aircraft (TAA): How to best deal with electrical failure and the subsequent loss of vital information from display screens while maintaining aircraft control and situational awareness. Pilots must be thoroughly trained in equipment operations, particularly with respect to emergency procedures. They must also learn not to become overly reliant on modern equipment, allowing it to replace basic flying, navigation and judgment capabilities. [Visit our Proficiency section for expert advice on maintaining your flying skills.]
In the past, many electrical-failure incidents became accidents not because of the loss of panel information, but because pilots didn’t realize that there wouldn’t be enough power to operate the flaps and landing gear until it was too late to plan a no-flaps landing and perform emergency procedures.
On July 11, 2007, at Washington’s Roche Harbor Airport, a Cessna 172RG’s landing gear collapsed just after touchdown, resulting in substantial damage. Nobody was injured. The pilot said that as he approached the vicinity of Roche Harbor, the airplane experienced a partial electrical failure. He decided not to attempt to troubleshoot the problem, and elected to land quickly for fear of a possible electrical fire. After activating the landing-gear handle, he was able to ascertain that the gear was extended by looking in mirrors affixed to the wings. The landing-gear lights on the panel, which would have indicated whether the gear had locked down, didn’t illuminate because of the electrical problem. (The pilot didn’t perform the emergency-gear-extension procedure, which involves using a hand pump until there’s heavy resistance.)
Although the focus of the NTSB’s safety recommendation was an Airbus A320, reports filed by pilots to NASA’s Aviation Safety Reporting System (ASRS) prove that there’s a broader issue in play. [Turn to “True Confessions” on page 64 for more information about the ASRS and its role in maintaining air safety.] Some of the more than 400 reports I found show the importance of carrying portable equipment to provide communication and navigation redundancy. While not all of these reports involve aircraft with glass cockpits, they do serve to establish that in-flight electrical problems aren’t exactly rare.
The pilot of a Cherokee Six and his family were about an hour into a pleasure flight (in instrument conditions) when the plane experienced an electrical failure. The pilot decided to return to the departure airport. He had a handheld GPS unit as a backup he could use for navigating and for viewing weather radar, and also a handheld transceiver. He declared an emergency using the handheld radio, but couldn’t get a response from the controller who had been handling the flight. The pilot tried using the emergency frequency, 121.5, but was unsuccessful. His wife dialed (800) WXBRIEF on her cell phone, but she couldn’t get through; she did, however, reach a 911 operator. She asked the operator to call the FAA and tell them that the flight had experienced an electrical failure and was returning to the departure airport. About 10 minutes out, the pilot made contact with the airport’s control tower and was cleared for a straight-in approach. The pilot wasn’t sure whether the gear had extended, and requested a flyby of the tower. The controller advised that the gear was up and cleared a block of airspace for the pilot to use in the hopes of getting the gear to drop. A repeat flyby confirmed that the gear was down, and an uneventful landing followed.
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