A US Airways Express flight takes off from National Airport in Arlington, Virginia, on April 26. (Jim Lo Scalzo/EPA.)

The Federal Aviation Administration says it is reviewing how and whether to make whole thousands of employees who were forced to take unpaid days off in April before Congress intervened, suspending the furloughs.

Under the budget cuts known as sequestration, the FAA began to furlough its 47,202 employees on April 21 for one day every two weeks until the end of the fiscal year on Sept. 30.

Among them are 15,000 air traffic controllers, whose absence — about 10 percent of the workforce was off that week— led to thousands of flight delays and cancellations at major airports.

By Friday, Congress, facing angry constituents, had intervened with bipartisan legislation to allow the FAA to return to normal staffing levels. The agency was given authority to redirect as much as $253 million from other areas of its budget to shore up staffing and operations.

Now the question is: will the government reimburse the lost pay of those who took off an unpaid day during the first week of a two-week pay period?

“The FAA is still reviewing its options for guidance to employees who were furloughed for one day,” spokeswoman Laura J. Brown said in a statement.

The FAA still does not know how many people took furloughs that week, or how much money was saved. That won’t be known until time and attendance slips from the two-week pay period are approved this week.

The agency seems to have these options: Allow furloughed employees to substitute a (paid) annual leave day for the furlough day they took; reimburse them in cash; or do nothing.

The annual leave option has the approval of the Office of Personnel Management, which posted new furlough guidance on its Web site last week allowing “retroactive substitution of excused absence for furlough hours taken in certain limited circumstances.”

Doug Church of the National Air Traffic Controllers Association, which represents controllers, did not return several phone calls seeking comment.

Stay tuned for the FAA’s decision.