Delta carrier Atlantic Southeast Airlines grounds 60 jets

— -- Atlanta-based ASA, owned by SkyWest, based in St. George, Utah, expects to complete the inspection of all those engines and to have all 60 planes back in service by late Thursday, spokeswoman Kate Modolo said. But that means several thousand more travelers Thursday could be affected.

The planes involved are CRJ-200s made by Canada's Bombardier and equipped with engines from General Electric.

Kathleen Bergen, a spokeswoman for the Federal Aviation Administration in Atlanta, said ASA officials discovered Tuesday that the engines involved had been allowed to exceed the maximum of 4,000 hours of operation between inspections. That, she said, required the immediate grounding of the planes on which the engines are mounted until inspections and any necessary repairs are completed.

Modolo refused to say how many flights were canceled or divulge how many passengers were affected by the groundings.

But based on the number of planes involved — 40% of ASA's fleet of 152 regional jets — and its approximately 800 scheduled flights a day, the loss of all 60 planes from service for a day would mean the cancellation of about 320 flights.

The CRJ-200 has 50 seats, so the maximum number of passengers affected is around 16,000 a day. The actual number, however, is likely closer to 10,000 because flights during the relatively slow midweek period would normally be only about 60% full.

That's a fraction of the more than 250,000 travelers whose lives were disrupted in early April 2008 when American Airlines grounded all 300 of its 150-passenger MD-80s — many for several days — over a wiring harness problem.

Bergen said ASA officials reported the problem to the FAA late Tuesday and canceled "about 50 flights Tuesday night." ASA officials told the FAA Wednesday that they had canceled about 210 flights as of about 4 p.m. ET, she said.

ASA's Modolo said, "We do recognize the impact this is having on some passengers and sincerely apologize for the disruption." ASA is using Delta's reservations offices to contact passengers and to accommodate them where possible, she said.

Delta spokeswoman Betsy Talton said her airline put a majority of affected ASA passengers on other Delta carriers "within a matter of hours."

Delta now is the world's largest carrier after its acquisition last year of Northwest Airlines.

Delta said customers not contacted but who could be affected should contact its reservations office online or by phone, or contact their travel agent.