United is now canceling empty flights — but you won't find out until check-in

Every airline is suffering from the significantly-reduced travel demand due to the coronavirus pandemic.

Some are hurting worse than others, but one thing's for sure — airline schedules look a lot different than last year. Carriers worldwide have slashed flights to cut costs amid the reduced demand.

Given the ever-changing travel landscape and quarantine restrictions, airlines aren't 100% sure which flights will fill up — and which ones won't. Operating empty flights is costly and inefficient, and flexible change and cancellation policies can further stunt the number of passengers on a given departure.

That's why United's latest initiative aims to trim down the number of empty flights the carrier operates, though it may result in added inconvenience to select passengers.

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United recently introduced a new program that analyzes flight loads to identify candidates for possible cancellation. Should the loads drop too low, United will consider canceling the flight — assuming that passengers and crew can be reaccommodated and the plane doesn't need to be at the destination for another flight.

As first reported by Skift, this program apparently begins canceling flights within a week of departure. However, in an email to TPG, a United spokesperson indicated that it's happening with much less notice.

"In the interest of operating as efficiently as possible with the least amount of disruption to our customers, we are proactively canceling flights that have few customers on board but have multiple departure opportunities available... When a cancellation occurs, we are proactively notifying impacted customers 18-24 hours ahead of their scheduled departure and automatically booking them on a new flight the same day or they may select an alternate flight that works best for them."

Though the program began in mid-August, fewer than 1% of the carrier's flights have been canceled. To be considered for cancellation, flights must have low load factors and multiple alternate segments available for rebooking. As such, the algorithm runs most frequently on flights between hubs or to major destinations.

Limiting last-minute cancellations to flights between large airports makes sense — United has more options to reaccommodate flyers without as much disruption.

If your United flight ends up getting canceled, you can select an alternate one that suits your schedule. You're also entitled to a full refund, even if you booked a nonrefundable fare.

Related: How to determine if your flight will be full

But sometimes you need to get where you're going, and a refund doesn't cut it. Unfortunately, with this new program, United's breaking from the industry-standard practice of schedule integrity.

Before the pandemic, when an airline sold a flight, you could expect the carrier to operate it — barring unforeseen delays due to mechanical problems or weather issues. Now, however, United's playbook has changed.

It'd be one thing if United canceled empty flights a week before departure, but notifying customers of cancellations during the check-in window is downright deceitful. At that point, it's likely too late to rebook yourself on another carrier or cancel your planned trip.

Related: United’s back to issuing refunds for 2-hour schedule changes

If you've got an upcoming United flight, be sure to double-check how full it is. If there are lots of seats for sale, cross your fingers that the flight doesn't get canceled.

And if you're considering booking a new United flight, beware. If the flight doesn't fill up, there's a (small) chance the airline will ultimately cancel your flight within 24 hours of departure.