Southwest Airlines' long-awaited flights to Hawaii are likely going to be delayed for months due to the government shutdown, executives said Thursday.

It is the first time the airline has put a timetable on the impact of the shutdown.

Southwest Chief Operating Officer Mike Van de Ven said the airline has a "reasonable chance'' of beginning service by the end of March if the shutdown ends within a week.

"Otherwise, it will actually be in the second quarter,'' he said.

The second quarter runs from April through June.

Southwest had hoped to begin flights early this year but the shutdown put its efforts to obtain Federal Aviation Administration certification for long, over-water flights on hold.

"Until the government shutdown ends we are at a total standstill,'' Van de Ven said on the airline's earnings conference call.

Southwest CEO Gary Kelly said the airline will be able to begin Hawaii flights approximately six to eight weeks after the FAA approval process resumes. Before the shutdown, he said, Southwest was aiming for a Feb. 1 start up, though it never publicized that target date.

If the shutdown ends within a week, that means the airline could begin flying by mid-March. But there are few signs an end is near, which is why executives told Wall Street the launch of flights could push into the April-June period. Southwest's first flights will be from California to Hawaii. Inter-island flights would come after that.

Southwest Airlines said the shutdown, which began Dec. 22, has cost an estimated $10 million to $15 million in lost revenue so far in January.

Southwest also said Thursday it plans to end service to Mexico City on March 30.

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