NEW YORK – The government said Thursday that airlines virtually wiped out three-hour tarmac delays in April before huge fines for holding passengers on the runway went into effect.

Airlines faced fines up to $27,500 per passenger for tarmac delays of more than three hours as of April 29.

Carriers improved their overall on-time performance, as well. The 18 airlines that report statistics to the Transportation Department were on-time 85.3 percent of the time in April, compared with a rate of 79.1 percent a year earlier and 80 percent in March. Most delays were caused by late-arriving aircraft and aviation system delays, which include bad weather, heavy traffic, or airport and air traffic system slowdowns.

U.S. Airways posted the best on-time rate among major mainline carriers. It was third in the overall rankings behind Hawaiian and Alaska Airlines. American Airlines reported the worst on-time rate of big U.S. carriers. Its sister carrier, regional airline American Eagle, was last among all airlines reporting.

Only four planes were stuck on the tarmac for more than three hours, down from 25 in March and 81 in April 2009. One flight, an American Airlines jet from Atlanta to Miami, was stuck for more than four hours.

In April there were long stretches when most of the nation was free of severe weather, according to the National Weather Service. Good weather often helps airlines avoid delays.