By Dr. Bill Tuccio
A privately hired de Havilland DHC-3T “Otter” plane impacted mountainous terrain near Aleknagik, Alaska, August 9, 2010. The pilot and four passengers were killed, including Ted Stevens, U.S. Senator from Alaska. Four other passengers were injured.
The aircraft was not equipped with any electronic recording equipment, nor was it required to. NTSB investigators used information from sparse GPS position reports transmitted by satellite, engine instruments, and two surviving passengers who were seated in the rear of the aircraft to determine what happened in the accident. This limited information, however, did not reveal crucial details about the pilot’s actions (or lack of actions) in the final three minutes of the flight.
The NTSB determined the probable cause of the accident to be, “the pilot’s temporary unresponsiveness for reasons that could not be established from the available information.” Ultimately, the lack of a cockpit recorder system with the ability to capture audio, images, and parametric data hampered investigators’ ability to determine exactly what happened.
About two years after the NTSB concluded that investigation, an Alaska Department of Public Safety Eurocopter AS350 lost control and impacted terrain, near Talkeetna, Alaska, March 30, 2013. The pilot, an Alaska State Trooper, and a stranded snowmobiler were killed.
In this case the NTSB discovered exactly what happened. The NTSB determined the probable cause was, “the pilot’s decision to continue flight under visual flight rules into deteriorating weather conditions, which resulted in the pilot’s spatial disorientation and loss of control.” Significantly, investigators determined where the pilot’s attention was directed, his interaction with the helicopter controls and systems, and the status of cockpit instruments and system indicator lights. The investigation found that the pilot reset a key instrument at an inappropriate time – known as caging the attitude indicator. With these details known, the NTSB produced an animation of the accident flight.
In this case, a recorder—voluntarily installed and capable of recording cockpit audio, video, and parametric flight data—made all the difference. NTSB investigators were able to determine the details of what transpired in the cockpit.
Once again this year recorders are on the NTSB’s Most Wanted List of transportation safety improvements. We have been advocating for image recorders since 1999, and trying to follow the lineage of our repeated recommendations related to recorder technology is a complicated process. One of our most significant recommendations was issued to the Federal Aviation Administration in 2003—and it has yet to be implemented. Essentially, the NTSB asked the agency to require all turbine-powered, nonexperimental, nonrestricted-category aircraft manufactured prior to January 1, 2007, that are not equipped with a cockpit voice recorder, and, that are operating under Title 14, Code of Federal Regulations, Parts 91, 135, and 121, to be retrofitted with a crash-protected, image-recording system by January 1, 2007.
Operators shouldn’t wait for the FAA to act. (And, thankfully, the operator of that DPS helicopter didn’t wait to be told to install recorders.) With the reduced cost of micro-electronics and reduced size of components—including cameras—operators should look into the future and equip all modes of transportation with recorders. The data collected from these devices not only can inform investigators in the tragic—and hopefully unlikely—event of a crash, but can also be used by operators themselves to make critical changes to address safety problems—ideally, before the NTSB shows up at the scene.
Bill Tuccio is an aerospace engineer in the NTSB’s Vehicle Recorder Division, Office of Research & Engineering. He holds a PhD in Aviation.