From PBS NewsHour.
At the start of three planned days of hearings, federal investigations closely examined the discrepancies with altimeters — vital instruments that measure how high an aircraft is flying — and whether that was a factor in the Jan. 29 collision between an Army helicopter and a regional jet that killed 67 people at Ronald Reagan National Airport.
NTSB investigators found that the helicopter was flying up to 100 feet higher than the 200-foot altitude limit for the helicopter in the area, according to the barometric altimeter the pilots use. The questions posed by board members explored how the crew aboard the helicopter was flying higher than what their barometric altimeter indicated.
“Notably, the barometric altimeters continued to be 80 to 130 feet lower than the helicopter’s determined altitude above sea level when flying at speed over the tidal portion of the Potomac River,” NTSB investigator Marie Moler said during the Wednesday hearing. The board wanted to know if this amount of difference would be considered impactful for pilots during flights.
U.S. Army helicopter test pilot Kylene Lewis said a discrepancy of 80 feet or so “would not be cause for alarm,” adding that she generally relies more heavily on one altitude instrument over the other, “depending on what I’m doing and what altitude I’m at.”
Jennifer Homendy, the NTSB chair, said that tests in forward flight with 12th Battalion helicopters, of which one of their units was involved in the January crash, showed similar discrepancies and asked federal aviation experts what kinds of errors contribute to this kind of difference in altitude information.
“This conversation makes me conclude that this feels like this is an inherent limitation of a barometric altimeter,” Homendy said.Watch PBS News for daily, breaking and live news, plus special coverage. We are home to PBS News Hour, ranked the most credible and objective TV news show.
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