Flight cancellations at Dallas-Fort Worth International Airport dragged on for a fourth day Friday as dozens of hail-damaged American Airlines planes remained out of service in the wake of Tuesday's powerful storm that brought tornadoes to North Texas.

On Friday, American canceled 296 arrivals and departures as mechanics inspected and repaired planes pounded by golf ball-sized hail. The number of cancellations is down slightly from Thursday when 326 flights were canceled. On Wednesday more than 450 flights were cut from numerous airlines' schedules.

It is still too early to estimate the cost of the repairs and loss of revenue for Fort Worth-based American. The airline recently filed for Chapter 11 bankruptcy and analysts say Tuesday's storm could cost American millions of dollars.

American said it won't know the extent of it until it finishes repairing its aircraft. On Thursday night, the airline reported 55 planes still out of service due to damaging hail. All of American Eagle's aircraft, however, are once again in the air.

In May of last year, another severe hailstorm disrupted flights at DFW Airport, grounding 50 American Airlines planes. At the time, the airline said that its second quarter revenue was $60 million down because of extreme weather and a lower travel demand for Japan following the devastating earthquake and tsunami. Similarly, when American canceled 8,000 flights in last year's snow and ice storms, it reported a $50 million loss in revenue.

So far around 1,900 flights have been canceled at DFW Airport, the airline's hub. On a normal day, American operates 1,500 flights out of the airport.

After a series of tornadoes ripped through North Texas on Tuesday, roughly 1,400 travelers spent the night in terminals. Airport employees distributed cots, blankets, pillows, and toiletry kits to the stranded passengers while thousands more booked rooms in area hotels.

The National Weather Service estimates that as many as a dozen twisters touched down wreaking havoc in North Texas. According to Red Cross estimates, the slow moving storms damaged at least 650 homes.

April is typically the worst month in the tornado season, which stretches from March to June. National Weather Service meteorologist Matt Bishop said Tuesday's outburst suggests that we're on pace to be above normal this year.

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