United Continental has appointed an acting boss after its chief executive suffered a heart attack last week.Brett Hart, the airline’s general counsel, will take over from Oscar Munoz immediately.
Mr Munoz suffered a heart attack shortly after taking up the role.
The world’s second-largest airline is due to report third-quarter results on Thursday, with strong profits expected by analysts.
The chairman, Henry Meyer, said: “Brett has taken on increasing responsibility beyond general counsel over the last few years in the operations and customer-facing areas of the company.”
Mr Hart, 46, joined United five years ago from Sara Lee and was previously was a law firm partner and a lawyer for the US Treasury.
The airline did not say how long Mr Munoz would be on medical leave, saying it was “too soon to know the course of treatment and timing of recovery”.
The lack of information given about Mr Munoz’s condition has attracted criticism.
Vicki Bryan, an analyst for bond research firm Gimme Credit, said that United’s statement last week about the chief executive’s health was surprisingly sparse and raised more concerns than it answered.
She said that United needed to be more open, “particularly in light of United’s substantial management upheaval in recent months”.
Mr Munoz took over at United only last month after Jeff Smisek was forced out for allegedly making deals with public officials in New York and New Jersey.
It has been accused of maintaining unprofitable flights that were popular with politicians in return for favourable government subsidies and better airport transit deals.
Merger struggles
Mr Munoz had been appointed chief executive in a bid to clean up the company and deal with a litany of staff and customer complaints.
The company had also struggled under Mr Smisek to merge the operations of the former United and Continental airlines after the two airlines merged in 2010.
United Continental shares have fallen 15% this year and closed on Monday at $56.75, valuing the company at just over $21bn (£13.5bn).