JetBlue Airways Corp. passengers sleep and work on computers Thursday as they wait for flights at New York's John F. Kennedy Airport. JetBlue tried to calm criticism Thursday after passengers were left waiting on planes at a New York airport for as long as 10 1/2 hours during a snow and ice storm. Calling the delays unacceptable, the airline said in a statement it would offer refunds and free flights to passengers who were delayed on planes for more than three hours.

New York ? Hundreds of passengers who were stranded on parked JetBlue planes for up to 10 1/2 hours could have been evacuated sooner if the airline had not waited to ask airport officials for help, the company founder said Thursday.

The airline acknowledged that it hesitated nearly five hours before calling in shuttle buses to unload 10 jets that spent the day sitting on runways at Kennedy Airport because of icy weather and gate congestion.

While they waited, exasperated passengers sat within sight of the terminal without food, adequate restrooms or a reasonable explanation as to why they were not moving.

JetBlue officials finally phoned the Port Authority of New York and New Jersey, which runs area airports, at 3 p.m. to ask for staircases and buses to get people off the planes and back to the terminal.

“We should have called them sooner,” said JetBlue founder and CEO David Neeleman.

Once they did, some passengers were free within 30 minutes. Others had to wait while the Port Authority shoveled out snow-covered equipment and rounded up drivers.

Many of the stranded passengers did not return to the terminal until 6 p.m. Most had boarded their aircraft about 8 a.m. Some of the jets were incoming flights that had been on the ground since 10 a.m. Six flights were stranded for more than eight hours.

Neeleman said he could not apologize enough.

“We should have done better,” he said. “There was an opportunity to do better.”

JetBlue’s problems began developing when snow and ice pellets made takeoffs difficult but did not stop landings, Neeleman said, resulting in the airline accumulating 52 airplanes at a terminal with 21 gates.

He said the airline held out too long for a break in the icy conditions, then had planes “freeze to the ground” where they had been waiting.

Weather delays of up to six hours continued to plague JFK on Thursday. More than 300 flights were canceled. At Newark Liberty International Airport in New Jersey and LaGuardia Airport, delays averaged more than two hours.

Terminals at JFK filled with passengers trying to arrange alternative flights. JetBlue canceled 195 of its 568 planned flights in an attempt to avoid being overwhelmed for a second straight day.

On Thursday, JetBlue promised a full refund and a free round-trip flight to customers delayed aboard an aircraft for more than three hours. Passengers with canceled flights were being offered a refund. All other passengers with travel booked through Monday were being offered a chance to cancel and rebook without having to pay the usual fee.