WASHINGTON — Delta Air Lines, hobbled by a two-day service meltdown, has been offering passengers delayed three hours or more travel vouchers, flight change fee waivers and hotel rooms when available.

But passengers whose trips are disrupted by delayed or canceled flights should know all their options.

According to Delta’s 51-page conditions of carriage, the airline will give passengers a full refund, in the original form of payment, in the event their flight is canceled or diverted or delayed more than 90 minutes.

“In the event of flight cancellation, diversion, delays of greater than 90 minutes,” the conditions say, “Delta will (at passenger’s request) cancel the remaining ticket and refund the unused portion of the ticket and unused ancillary fees in the original form of payment.”

The conditions of carriage further state that the refund will apply to the unused portion of the ticket, or if no portion of the ticket has been used, “the refund will be an amount equal to the fare paid.”

If you accept a travel voucher instead of a refund, you may be entitled to more.

If hotel accommodations are not available for passengers delayed between 10 p.m. and 6 a.m., the airline will provide a travel voucher of up to $100.

Even if a computer outage hadn’t affected Delta’s entire operation, passengers would still be entitled to the forms of compensation spelled out in the conditions of carriage.

“They have a number of options,” said Ashton Morrow, a Delta spokeswoman.

Morrow said the conditions of carriage are posted on Delta’s website and are incorporated into every ticket the airlines sells.

Delta passengers who booked their tickets through a third-party vendor, such as Travelocity or Expedia, can work directly with Delta to receive vouchers or refunds. However, those passengers will have to go through the third-party vendors to change flights, and change fees could apply in those instances.

A computer failure early Monday caused the airline to cancel 1,000 flights Monday and 800 Tuesday. By early Wednesday afternoon, the airline had canceled almost 300 more.

“We’re focused on getting the operation on track,” Morrow said.