Last Friday’s power outage in Heathrow Airport disrupted vacations across the world, causing countless thousands of travelers to miss prepaid reservations and forgo long-anticipated adventures.

Among them were Sheila Addison, a therapist from Seattle, who missed out on a four-day whisky-tasting in the Scottish Highlands, forfeiting a $500 nonrefundable hotel room and a rare break from her work routine; Zachary Wang and friends from Brown University, who lost $260 in “Les Misérables” tickets, $180 from an Airbnb reservation and two days of spring break in London; and Steve Wehr of Hyde Park, N.Y., who missed two days in Jordan — including the first day of a cruise — a loss of about $1,500.

Who pays when your vacation gets ruined through no fault of your own?

The answer, all too often, is you. Though travelers can recoup some losses through refunded flights and vouchers for meals and hotel stays, airlines generally do not pick up the tab for reservations that can’t be canceled, expensive last-minute flights that must be booked, or missed family events like weddings.

Unfortunately, there is no perfect way to protect yourself, but there are three imperfect ones. Here’s what you can do:

Find the right travel insurance

Mr. Wehr does not expect to recover that $1,500 he lost by missing two days in Jordan. “We didn’t have trip insurance,” he lamented in an email.

It probably wouldn’t have mattered. Travel insurance is generally a “covered peril” type of policy, meaning that the fine print has a list of events that you are covered for, like illness, hijacking and natural disasters. Guess what is almost never on there: airport power outages.

“It covers a lot. It doesn’t cover everything,” said Stan Sandberg, a co-founder of TravelInsurance.com, an online marketplace. Companies try to update policies to match the current travel environment, he said, but only one he knew of covered what happened at Heathrow.

Indeed, Travel Guard’s Deluxe and Preferred plans specifically protect against airport closures caused “by a fire or a power outage.” But they “must result in a delay of the Insured’s Trip for at least 48 consecutive hours,” according to the policy. So even if Mr. Wehr had chosen one of those plans, he would have had to show that his delay was long enough. Claims adjusters are sticklers by nature.

Comparison shop on sites like TravelInsurance.com, or its competitor SquareMouth, and make sure the policies best cover the risks that fit your own circumstances (infirm relatives) or your destination’s (hurricanes). It is usually best to avoid policies offered at checkout by airlines and online travel agencies, which are generally one-size-fits-all, and to not put too much hope into policies included with some credit cards.

Another option is a Cancel for Any Reason, or CFAR, plan that typically allows you to back out of a trip, no questions asked, though you often don’t get a 100 percent refund. But most require you to cancel 48 hours before the trip starts, Mr. Sandberg said — which wouldn’t have helped the typical Heathrow strandee.

But Iris Planamento of Manchester Township, N.J., was not typical. She was on her way to see London, Paris and Normandy with EF Go Ahead Tours when her flight got canceled. The company’s CFAR plan is AnyReason Protection, a $75 add-on that offers trip credit, not your money back — but that expires only at airport check-in.

Ms. Planamento was delighted to confirm she was covered and plans to rebook soon. “Give a plug to the company,” she said — not a common sentiment among stranded travelers.

Leave yourself enough time

Losing one day of a weeklong trip to Paris is a shame, but don’t ask the rest of us for sympathy. Missing a wedding or a cruise ship departure is another story.

Here’s a basic rule: Book flights that are scheduled to arrive at least 24 hours in advance of anything you can’t miss. You’ll want to extend that cushion based on a number of factors, like how crushed you’d be to miss the wedding and whether your cruise ship’s next port of call is reachable by 20 daily flights or one monthly tugboat.

You’ll also want to consider your backup plan. If you’re headed from New York to Chicago and your flight gets canceled, there’s a pretty decent chance you’ll be on another flight that day from the same or another area airport, or, worst case scenario, you could drive overnight. There are fewer options if you’re headed from Hawaii to Dubrovnik, Croatia, to catch an island-hopping cruise.

The carrier you choose matters. As you book, look at how many flights a day each airline has, and lean toward the one with the most flights, even if it’s somewhat more expensive. Airlines are often very stubborn about booking you on competitors, sometimes even if they’re in the same alliance.

Your wallet size matters, too. Those with a financial cushion need less of a time cushion: If you’d be willing to plunk down a few grand for a new last-minute flight, a 24 hour cushion might be plenty.

Fight, efficiently and politely

Gloria-Jean Masciarotte’s flight to London turned around midflight and returned to Boston. She and her family were able to cancel most of their plans, but “the fly in the ointment,” she said, was their $3,146 Airbnb rental. Airbnb did not declare the outage a “major disruptive event” — nor should they have, given the company’s definition of that term. But after two days of texts and phone calls, she said, she was able to finagle a $2,730 credit.

Once something does go wrong, take action. Be the person who waits in line at the customer service desk while on hold with the customer service line and writing the airline via social media. Get in touch with hotels as soon as possible to ask for a refund, but settle for a partial one. Realize that if your prepaid plans include a vacation rental, it is your host, in most cases, who must grant a refund, not the company. They also stand to lose money through no fault of their own, so be really, really nice.

Actually, be nice to everyone, even if you happen to run into, say, the people in charge of Heathrow’s backup power supply. They’re already stressed enough.

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