Allegiant flights snarled by computer system outage

Updated 4:50 p.m. ET

About 4,000 Allegiant customers suffered disrupted flights today (July 18) after a computer outage disrupted the leisure carrier's nationwide operation.

The outage – which began around 8:25 a .m. ET lasted until about 4 p.m. ET – forced Allegiant employees to manually check customers in for their flights. That dramatically affected the company's ability to stick to its flight schedule. The outage also disable Allegiant's website.

Allegiant says of the 250 Allegiant it was scheduled to operate today, eight have been cancelled and another 18 have been rescheduled to operate Saturday (July 19). Dozens of other Allegiant flights appeared to have been delayed today, likely affecting thousands of additional customers.

Unlike most U.S. carriers, Allegiant does not offer daily service on most of its routes. So, if a flight is canceled, it could be several days until the carrier's next scheduled flight, depending on the route.

Allegiant has apologized for the issue, and says it will provide compensation for affected fliers.

For customers who have been delayed overnight, Allegiant says it will provide:

- A full refund of the price of passengers' affected flight

- A $200 voucher, good for future travel on Allegiant

- Reimbursement for hotel accommodations for displaced passengers

For customers whose flights have been canceled, Allegiant says it will offer:

- A full refund of the price of passengers' itinerary

- A $300 voucher, good for future travel on Allegiant

- Reimbursement of "reasonable alternative transportation expenses"

Allegiant flies primarily from small cities to Las Vegas and other focus cities in sunny vacation destinations. Among the carrier's other focus cities: Fort Lauderdale; Myrtle Beach, S.C.; Orlando Sanford; Phoenix/Mesa; St. Petersburg, Fla.

The business model has been successful for Allegiant, which has emerged as one of the USA's most-profitable airlines this decade.