NTSB finds Army chopper in fatal midair crash with plane was above altitude limit [View all]

https://apnews.com/article/midair-collision-ntsb-washington-dc-army-helicopter-40f94a495e2e60b9adc5b9a49cce6437

Investigators probing the January midair collision of a passenger plane and an Army helicopter over Washington that killed 67 people found the chopper was flying higher than it should have been and its altitude readings were inaccurate.
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The hearing opened Wednesday with a video animation showing where the helicopter and airliner were leading up to the collision. It showed how the helicopter flew above the 200 feet (61 meters) altitude limit on the helicopter route along the Potomac River before colliding with the plane.

Investigators said Wednesday the flight data recorder showed the helicopter was actually 80 feet to 100 feet (24 to 30 meters) higher than the barometric altimeter the pilots relied upon showed they were flying. So the NTSB conducted tests on three other helicopters from the same unit in a flight over the same area and found similar discrepancies in their altimeters.

Dan Cooper with Sikorsky helicopters said that when the Black Hawk helicopter involved in the crash was designed in the 1970s, it used a style of altimeter that was common at the time. Newer helicopters have air data computers that didn’t exist back then that help provide more accurate altitude readings.
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