United Airlines says chairman and chief executive Jeff Smisek and two other top officials have stepped down in connection with a federal investigations involving the regional airport authority.
Smisek was replaced "immediately" by board director Oscar Munoz, the airline's parent United Continental Holdings said on Tuesday (local time).
Also leaving were the company's executive vice president of communications and government affairs, and its senior vice president of corporate and government affairs.
United said the surprise departures related to a federal investigation associated with the Port Authority of New York and New Jersey, which operates John F Kennedy, LaGuardia, Newark and other key airports in the New York metropolitan region.
No details were given on the probe, but media reports for the past year have said the airline was being investigated over alleged favours done for the then-head of the Ports Authority, David Samson, as United was seeking public investment in the Newark Airport.
United would only say that its internal investigations into the case "do not raise any accounting or financial reporting concerns".