Live Blog: NTSB examines collision avoidance technology in Flight 5342 hearing

WASHINGTON — The National Transportation Safety Board began its third and final day of investigative hearings Friday to reveal new information and question experts about the fatal collision of a U.S. Army Black Hawk helicopter and American Eagle Flight 5342 in January.

The hearings were expected to bring in testimony from the U.S. Army, the Federal Aviation Administration, the NTSB and experts in the manufacture of helicopter avionics. A live stream of the hearing can be found in the video player above.

Friday’s panels were set to examine collision avoidance technology and safety management systems used by the Army and FAA.

Previous day’s panels examined the altimeter and other data systems in the Black Hawk helicopter and the safety of air traffic control in the D.C. airspace.

Follow along throughout the day with our live blog below:

Panel 4: Overview of Collision Avoidance Technology

The fourth panel brought in experts from the FAA, MIT’s Lincoln Laboratory, Collins Aerospace, the U.S. Army and PSA and American Airlines.

Topic areas for the panel include:

• FAA requirements for collision avoidance technology.
• Collision avoidance technology onboard American Eagle Flight 5342.
• The U.S. Army’s philosophy on collision avoidance technology.
• Combinations of technology solutions to mitigate the risk of future mid-air collisions.

The Army received scrutiny during the first two days for its policy of not using technology that transmits position to other aircraft when flying helicopters in the D.C. area. Rick Dressler, a former Army aviator and now manager at Metro Aviation, which operates medivac flights in D.C., said the Army’s refusal to use the technology, known as ADS-B Out, adds an “unacceptable layer of complexity and risk to the system.”

Much of the questioning Friday morning centered on the Traffic Alert and Collision Avoidance System (TCAS) used by most commercial aircraft in the U.S. During previous panels, experts have said collision warnings are generated nearly every day, and often several times a day, at airports as busy as DCA. On Friday, Steve Casner, a research psychologist with NASA, was asked about what effect so-called “nuisance alerts” — warnings generated when no collision is actually imminent — can have on pilots who regularly experience them.

“We become desensitized to the alert,” Casner said. “The alert ceases to become an alert. The likelihood that the alert is going to tell me something I don’t already know in my mind just deteriorates. You get what’s called the ‘cry wolf’ effect, from Aesop’s fable.”

Flight data shows the crew of American Eagle Flight 5342 received a TCAS alert approximately 19 seconds before the collision. Capt. Grant Clow, assistant director of flight operations for PSA Airlines, which operated Flight 5342, said he believes the crew would have been intently listening to radio chatter to learn if the threat was real or not.

“The radio frequency is kind of like a party line and all people, all crews on that party line are listening to kind of build a mental picture of the traffic,” Clow said. “I believe the PSA crew would have been listening with bated breath to what happened next. The next transmission was going to tell them whether the threat was mitigated and something they could deprioritize or whether a control instruction from ATC would be forthcoming that they would need to react to.”

Because the U.S. Army does not fly its helicopters near D.C. with ADS-B Out turned on, which would broadcast their position and altitude to other aircraft, the Black Hawk would not have appeared on Flight 5342’s display. Casner was asked what the human reaction would be to getting a TCAS alert and then seeing no traffic on instruments.

“Given the high workload of the situation there’s only so much time you can devote to that,” Casner said. “I can imagine looking and not seeing anything egregious or imminent. I don’t know what other choice there would be other than to return your attention to the landing.”

Check back with this blog throughout the day for further updates from the hearing.