In the United States, if your flight is canceled, significantly delayed or changed, airlines will rebook you on another flight, or at the very least try to rebook you.

Airlines will do more for passengers when the cause of a delay or a cancellation is their fault. An air traffic control outage isn’t, which means that what passengers can expect right now is limited.

You’re also entitled to a refund if your flight is canceled, regardless of the reason, or if a flight is significantly delayed or changed and you decide not to take it.

But airlines won’t guarantee other amenities, such as a hotel room in the case of overnight cancellation, ground transportation, or meal vouchers.

In the case of a tarmac delay, airlines are required to provide passengers some assistance: water and a snack within two hours of the start of a tarmac delay, unless there are safety or security reasons preventing this, according to the Transportation Department. Airlines don’t have to serve a full meal.

In the United States, airlines have three hours, for domestic flights, to move the plane to a place where passengers can safely disembark. This is four hours for international flights. However, travelers who get off the plane run the risk of not being allowed back on it.

Airlines including United Airlines, Delta Air Lines, and Alaska Airlines have issued waivers allowing travelers to change or cancel their flights without incurring any change fees or fare differences.

Waiting it out at the airport in an endless line during the current ground stop may not be the best strategy for Friday, said Jamie Larounis, a travel industry analyst.

“This won’t be a quick fix,” he said, adding that flight disruptions would likely ripple into the weekend.

Mr. Larounis said the priority for affected travelers was to get on another flight that departs in several days, booking a hotel as soon as possible if stranded outside your home city, and to consider train travel, if possible.

Scott Keyes, the founder of Going.com, a website that sends alerts for travel deals, suggested workarounds to calling an airline’s general customer service line. Travelers can try calling an airline’s international hotline, which will have fewer callers. Rebooking also might be easier to do using the airline app.

“It’s a race for any remaining seats, so the sooner you’re able to rebook, the better your odds for a remaining seat,” he added.