Airlines and travel experts are warning that a move by federal authorities to throttle back the number of flights at 40 major airports starting on Friday could disrupt people's travel plans across the U.S.

"Even if you're flying out of an airport that doesn't have reductions, there will be a domino effect across the entire system," said aviation expert Julian Kheel, CEO of travel booking site Points Path, adding that passengers should prepare for "significant flight disruptions."

One airline chief executive urged customers to buy a second ticket from another airline in case one flight is scrapped — a workaround that some travelers could see as beyond their means. 

"If you are headed to a wedding, funeral or something you must be somewhere for in the next few days — given the risk of flights [canceling] I would suggest passengers buy a backup ticket on another carrier that departs after the first ticket," Frontier Airlines CEO Barry Biffle said in an Instagram post on Thursday. 

"Carriers like Frontier will be putting you on the next available flight but that may not be until after your event due to the scale of this disruption," he added. 

Transportation Secretary Sean Duffy on Wednesday announced that air traffic in 40 "high-volume" airports would be reduced by 10% in the coming days to cope with shortages of air traffic controllers, who are working without pay amid the ongoing government shutdown.

The flight restrictions are expected to be phased in starting Friday, with airlines reaching the full 10% mark by next week, two sources familiar with discussions between the Federal Aviation Administration, Department of Transportation and the airlines told CBS News.

Some airports on the FAA's list for capacity cuts are already experiencing problems. Passengers flying out of Boston's Logan Airport on Thursday were starting to see flight delays and cancellations due to the shutdown, CBS News Boston reported. 

Airlines promise extra help — and refunds

As the air capacity cuts loomed, major airlines vowed on Thursday to alert customers on flight issues, help people rebook their travel, and provide refunds or credit if their trips are disrupted. 

"As schedule changes are made, we'll proactively reach out to customers who are impacted," American Airlines said in a statement to CBS News. 

The carrier also said that customers whose flights are canceled for any reason or who choose not to travel can change their flight or request a refund without penalty. American encouraged customers to stay up-to-date on their flight's status using its mobile app. 

The airline said that, from Nov. 7 to Nov. 10, it will trim its flight schedules by 4% at the 40 airports affected by the FAA capacity restrictions, the equivalent of about 220 flights canceled each day. That represents a small fraction of the 6,000 daily flights on those days, American noted. 

Southwest Airlines said it will notify customers if their flight is canceled and automatically rebook them on new flights. Customers who do not wish to be rebooked are eligible for refunds, provided they cancel a new itinerary arranged by Southwest at least 10 minutes before the new flight's departure, the airline told CBS News. 

Delta Air Lines also said it would allow customers to cancel flights without penalty between Nov. 7 and Nov. 9.

Check before you head to the airport

Tiffany Funk, co-founder of travel rewards site point.me, said travelers should be extra vigilant in monitoring communications from their airline before heading to the airport. "Pay attention to updates from airlines. If you're not getting emails, call them."

John Rose, chief risk and security officer at Altour, a travel management company, recommended that travelers use an airline's app to track inbound flights to anticipate any delays. 

"The main thing to watch is that the flight is still going, that it's on time. That's a trick that's easy to do on the airline's app. See where your plane is coming from and if it has any problems," he told CBS News. 

Rose added that it's important to look beyond the airports where cuts are implemented for travel disruptions, given that shortages of air traffic controllers in airport towers could affect airspace outside of such regions. 

"Recognize that even with the 10% cutback, other flights could be impacted beyond that, because we don't know where people are going to be calling in sick and having staffing shortages," he said.

But don't check luggage

Although travelers should avoid checking luggage, if possible, to minimize another potential hitch, Rose recommends packing essentials like medication and a change of clothes. 

"Plan to be stuck somewhere for an extra day," he said. 

He noted that international flights might be less prone to disruptions, given that airlines typically operate fewer flights a day to foreign destinations.

"Historically, the last flights to cancel are international because they tend to only fly there once or twice a day, and if they put you on the next flight, it's in a day or two," he said. 

When to book a backup fare

Travelers who are especially eager to avoid flight problems can get a backup ticket, Funk said. 

"If you have critical travel you cannot miss, then another ticket on a different carrier is always a good play," she said. "Every carrier will solve for these things differently, so get a ticket on another airline even if there's a connection."

Unused tickets can be canceled within 24 hours of purchase, she noted, so it's a relatively risk-free move. 

"If I had a trip scheduled in the next week that I didn't have to take, I would consider rescheduling it," said Kheel of Points Path. "If you do have to take a trip, you can book multiple flights on different airlines to try and protect yourself."

Despite the headaches for passengers, air travel remains safe during the closure of federal agencies, now on Day 37 and the longest government shutdown in U.S. history, Rose added.

"People's safety is not being compromised. The FAA is not going to put travelers in a higher-risk situation because of this," he said.