NTSB investigators asked Army officials detailed questions about ADS-B Out usage by FAA air traffic controllers and the Army helicopters this week during the Board’s fact-finding hearing into the Jan. 29, 2025 midair collision of a U.S. Army Black Hawk helicopter and a PSA Airlines CRJ700. The helicopter flight, designated PAT 25 and operated by the Army’s 12th Battalion, was an annual evaluation for the pilot with the use of night-vision goggles (NVG).
NTSB investigator Van McKenny asked Andy Deforest, U.S. Army commander of the Army Aviation Brigade, about the 12th Battalion’s policy for use of ADS-B Out at the time of the accident.
“Applying risk-management procedures at the time of the accident,” Deforest said, “we perceived the risk of security as paramount, knowing ADS-B Out and what signals it sends out. We assess that it was a risk that could be mitigated. So the policy the day of the accident was to have ADS-B Out off anytime you are conducting anything related to the mission, i.e., flying near a mission route or location.”
Asked what guidance led to this policy, Deforest said, “It was Army policy, which we were in compliance with, in addition to the MOU between the DOD [Department of Defense] and the FAA.”
McKenny asked whether the Army helicopters are still required to have transponders switched on and broadcasting Mode 3A and C, which Deforest confirmed. He also said that PAT 25 was using mission routes and sites that authorized having ADS-B Out switched off, which was the case.
He switched his questions to Rick Dressler, aviation site manager for medevac operator MedStar, asking, “How does the prevalence of non-ADS-B Out flights impact the operation in the DCA class B airspace?”
“It adds an unacceptable layer of complexity and risk to this system,” Dressler said. “When you look at the flight profiles and if we talk specific to night NVG operations, and we’ve heard how stressful and how demanding those flight regimes are, then when you are being given traffic information from ATC, which you may or may not most likely be unable to see, it’s remarkably difficult to see an aircraft at distance, and it becomes obviously quite easy within 2 miles or a mile. In the way that all of the civilian helicopter operators are configured, including law enforcement, we have a traffic-avoidance system. It’s not TCAS, but it’s [a traffic collision avoidance device], and it is ADS-B-dependent. So when you are scanning, goggles or no goggles, looking around [with] your goggles and you can or cannot identify an aircraft, your next step in your situation analysis is to scan your traffic system. That is completely useless if aircraft don’t show up because they’re not broadcasting, so…the [helicopter] user group finds that to be an enormous risk.”
McKenny asked Dressler how he deals with aircraft in the KDCA Class B airspace that aren’t broadcasting ADS-B Out, and his response was that he relies on ATC for Class B separation and also see-and-avoid techniques “and take whatever steps necessary to change our route, our altitude, our airspeed to avoid and further try and emphasize on frequency [what we’re doing].” This communication is important, he said, because some aircraft might be transitioning from a military base to KDCA, and “maybe they were coming off of another frequency. We will restate our mission profile in hopes that the other aircraft is now alerted to the fact that there’s an operational aircraft in the way.”
From the ATC perspective, aircraft without ADS-B Out don’t affect operations around KDCA. According to Clark Allen, former operations manager of the control tower at KDCA, “With our STARS radar that we use with fusion mode, ADS-B Out off has no impact.” He said he wasn’t aware of any safety or operational benefit, from an ATC perspective, to aircraft that are operating with ADS-B Out switched on.
Deforest confirmed that the PAT 25 flight was a training flight, including a check ride and NVG annual check, and that it included sensitive or classified operations that allowed ADS-B Out to be switched off. “It met all the criteria for the policy,” he said.
Generally, about 20% of flights in Battalion 12’s UH-60 fleet before the accident were done with ADS-B Out switched on. McKenny pointed out that during the investigation, the NTSB learned that on most of Battalion 12’s UH-60Ls, although they had been upgraded with ADS-B Out, the system wasn’t broadcasting because of an incorrect time source setting. This was corrected immediately after the accident based on an Army safety action message sent to all operators.
In any case, the accident helicopter’s Mode S transponder signal was broadcasting until the collision occurred. Its ADS-B Out had not been working for 730 days, and these installations had not been tested until after the time source issue was fixed after the accident. Testing is being done on a regular basis now, according to Deforest.