Helicopter in deadly DC airport collision had faulty altitude gauge, NTSB saysInvestigators testifying at a hearing into the January's mid-air crash in Washington DC suggest faulty altitude data may have led to a miscalculation.
Source: Helicopter in deadly DC airport collision had faulty altitude gauge, NTSB says (https://www.bbc.com/news/articles/cvg34jd8p2go?at_medium=RSS&at_campaign=rss)