American Airlines has cancelled 94 flights while it works to fix passenger seats that could come loose during a flight.
A flight from Boston to Miami had to make an emergency landing in New York last Saturday after a block of three seats disconnected from the floor. There were no injuries.
On Monday, a flight from New York to Miami returned to John F Kennedy airport after unsecured seats were discovered.
On Tuesday, the airline said that seats also came loose on a flight from Vail, Colorado, to Dallas-Fort Worth in Texas.
American said the problem affected 48 Boeing 757s and it hoped to have them back in service by Saturday.
Loose seats create a potentially dangerous situation if the plane hits turbulence. The BBC reports the faulty seats had recently been refurbished.
The Federal Aviation Administration is investigating the issue.
American Airlines vice president David Campbell said the seats in question had been used for 20 years without incident until now.