Canceled flights on a flight status board for an article about the Boeing 737 Max grounding.

The worldwide grounding of the Boeing 737 Max is causing hundreds of U.S. flights to be canceled every day, scrambling the travel plans of thousands of passengers.

The cancellations are likely to drag on until late April at the earliest. That’s because the Federal Aviation Administration is continuing to evaluate a fix proposed by Boeing to the software flaw that may have played a role in two recent fatal crashes of this model aircraft.

Unlike flight disruptions that result from bad weather or mechanical problems, however, these are planned cancellations, which means that airlines have more leeway when rebooking customers on other flights. Typically what happens next is that airline reservations computers automatically reschedule you on a different flight, and you should get notified by email, text, or phone. 

But it may be a very different trip from the one you originally booked. If you paid more for an aisle seat with more legroom, that nonstop trip you arranged may turn into a connecting flight with a middle seat in the back. The new flight could be scheduled to leave on a different day.

While the airlines will refund the upgrade charges—or even your fare if you reject the new flight—the airline isn’t under any obligation to get you to your destination at any particular time.  

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In disruptions caused by events out of the control of the airline—from hurricanes to a government-ordered grounding like this one—you aren’t owed compensation for any delay or inconvenience as long as you eventually get to your destination, says William J. McGee, aviation adviser for Consumer Reports.

“Unfortunately, the domestic airline contracts of carriage give all rights to the carriers and very few rights to passengers,” he says. “That’s why we’ve been advocating for years that we need a robust passenger bill of rights in the United States,” similar to what already exists in Europe

That said, passengers can improve the outcome by keeping in mind some basic advice on how to cope with flight disruptions of any kind. Here’s what passengers need to know:

Check to see whether your airline is affected. American, with 24 Max 8 jets now parked on the ground, says it’s “proactively” canceling 90 flights a day through April 24. Southwest, the largest 737 Max operator, with 34 of those jets, was scrubbing around 130 flights daily after the March 13 grounding order, but on Wednesday it announced that it had reduced its published flight schedule until April 20, which “should result in drastically reduced” cancellations. 

United Airlines, which has 14 of the larger Max 9 that is also grounded, says on its website that it does not expect a significant impact on its operations. 

Foreign operators of the grounded jet with service to the U.S. include Air Canada and Norwegian, both of which have canceled flights. The other major U.S. airlines—Alaska, Delta, and JetBlue—don’t have any Max models in their fleets.

If you’re booked to fly on any of the affected airlines, in many cases you can find information about the kind of plane your flight was scheduled to use by looking at your reservation. But don’t assume that your flight is okay if isn’t on a Max. The airlines operating the most Max jets say that they are trying to minimize the impact on consumers by moving aircraft to the routes where they’re needed the most.

“They are doing a bit of borrowing from Peter to pay Paul,” says Henry Harteveldt, a travel industry analyst with Atmosphere Research Group.  

American, in a message to customers, says that it has “re-routed aircraft throughout our network” and that a flight that was not scheduled on a Max “might be canceled to enable our team to cover a Max route with a different plane.”

On the other hand, a flight that was originally via a Max could still operate as scheduled, just with a substitute aircraft. In short: Don’t assume that what your reservation says about the plane assigned to your flight will still hold.

American explains that “these decisions are being made in order to impact the smallest number of customers.” But Consumer Reports’ McGee says that the lack of information on how these choices are made is troubling.

Because there is no way to know in advance which flights will eventually be rescheduled or canceled, “the only practical advice to offer consumers is to remain in close touch with the carrier and check for alerts right up until the day of departure,” he says.

Be alert to messages from your airline or travel agent. If you booked your ticket through an airline’s website or app, you should get notifications from the airline about any flight changes.

But if you bought your ticket through a travel agency, you’ll need to work with it if your itinerary changes. 

“The travel agency will contact the customer directly,” says an American spokesperson. “If the flight is unacceptable, they can make changes via the travel agency or request a full refund.”

That applies to online travel agencies such as Expedia and Priceline as well as to traditional travel agents.

Consider what your options are if you aren’t satisfied. Don’t assume you have to accept the first alternative that the airline computer automatically coughs up if you’re rebooked. If you’re being told the next available flight is three days later than what you booked—causing you to miss that family reunion or meeting—get on the phone and plead your case; a sympathetic airline or travel agent may be able to pry a seat loose from a flight that looks full.   

You can ask for a refund, but it’s worth weighing any inconvenience caused by the new plan you’re being offered against what you might find if you cancel and start over.

You could take the refund and apply it to a trip on another airline, but the closer to your departure date you are, the more limited your available flight options may be, and fares booked close to departure during busy travel periods can be much higher. So before you get on the phone and start negotiating, it’s a good idea to research other flight options via an online search engine, such as Kayak, or the airlines’ websites.

“There aren’t very many empty seats right now,” Harteveldt adds. “The grounding is effectively removing more than 70 planes from the system, most with around 170 seats on them. Multiply that by several hundred flights a day, and there’s no other way to describe it: It’s going to be a real mess.”