Just days ago, a Virgin Atlantic flight departing Hong Kong Airport for London's Heathrow was stuck on the tarmac for seven hours.

That event fell on the heels of an even longer delay: United Airlines passengers flying from Newark, N.J., to Hong Kong were trapped onboard for 14 hours in frigid Newfoundland, Canada. The plane had made an emergency landing for a sick passenger and couldn't take off again as planned because of a mechanical issue. Because Goose Bay Airport, a Canadian air force base, didn't have the customs officials to process passengers, they couldn't deplane. A different plane eventually returned them to Newark, where they received meals, hotel accommodations and compensation. That gave passengers needed rest and sustenance, but probably small comfort. But it was more than the airline was required to provide.

This seems like a good time to revisit passenger rights.

According to the U.S. Department of Transportation, fliers stuck on a plane for two hours must receive food, water, working toilets and medical care if needed. After three hours for domestic flights or four hours for international flights, passengers must be allowed to deplane. But beware: Those who do may not be able to reboard, and airlines aren't required to offload checked bags. Airlines also are not obliged to offer financial compensation, though many do.

These rules apply only to planes at U.S. airports (fliers are compensated for delays in Europe). There are also a few exceptions. For instance, if an airline determines that deplaning would be unsafe, the rule is waived.

Canada is catching up with the U.S. The government is reviewing proposed regulations to protect air passengers.

To file a complaint about an airline with the DOT, go to https://­www.transportation. gov/airconsumer/file- consumer-complaint.

Contact Travel Editor Kerri Westenberg at travel@startribune.com, and follow her on Twitter: @kerriwestenberg.