United Airlines has bid goodbye to chief executive Jeffrey Smisek and two other senior executives while the federal investigation on the airline's relationship to former chairman of Port of Authority of New York & New Jersey David Samson is clearly ongoing. The dismissal also comes amid the airline's financial turnaround in 2015 after earning as much as $1.7 billion mid-year.

United Airlines owner United Continental Holdings announced the departure of Smisek and the two executives on Tuesday, adding a more dramatic element to the controversy the airline is currently facing, according to Bloomberg.

The ousting of Smisek came as a surprise since he has led the airline to earn $1.7 billion in the first half of the previous year by tumbling fuel costs. The figure was said to be ten times the previous earnings of the company in 2014.

Though the financial turnaround was very beneficial to United Airlines, it didn't help Smisek in keeping his position. Hence, United's audit committee head and railroad executive Oscar Munoz was abruptly named new CEO and president, as per Huffington Post.

"The departures announced today are in connection with the company's previously disclosed internal investigation related to the federal investigation associated with the Port Authority of New York and New Jersey. The investigations are ongoing and the company continues to cooperate with the government," United Continental Holdings stated in a statement.

Federal prosecutors are reportedly probing deep into United Airlines' ties with Samson in line with the direct flight the airline offered while the latter was still the Port Authority chairman. When Samson resigned, the flight that directly traversed Newark, New Jersey and Columbia, South Carolina was terminated.

An internal investigation was launched in February amid a government probe on the relationship between Samson and the airline because of the former's role as Port Authority chairman and his ownership over a private law firm, Independent has learned.

Jeffery Smisek was United Airlines' CEO since 2010.