(Some United Airlines customers don't understand what is included with basic-economy fares.David Goldman/AP Photo)

United Airlines' basic-economy tickets have been widely available for only a few weeks, but the new fare class is already confusing and frustrating some customers.

Basic-economy tickets are cheaper than economy tickets, but they come with some notable restrictions. Specifically, the new fare class limits customers to only one small personal item. United's basic-economy tickets also don't allow people to choose, change, or upgrade seats, and require the passenger to board in the last boarding group.

United began rolling out the new fare class in February and completed launching it in all domestic markets by mid-May.

United has positioned basic economy as a low-cost fare for budget travelers. But now that the company has made the new fare class available nationwide, it's becoming clear that not all customers fully understand what it entails.

Several United customers have used Twitter to tell the airline they didn't know about basic-economy restrictions when they booked their flights:

However, the airline alerts customers about basic-economy limitations before they purchase a ticket.

After selecting the cheaper ticket, a window pops up to alert the buyer about its restrictions. The customer is also presented with a comparison of basic economy and economy, along with the option to select the more expensive ticket instead.

The customer must acknowledge the basic-economy ticket works for them before proceeding to checkout.

(United prompts customers to acknowledge they understand the restrictions that come with a basic-economy fare.Screenshot/United)

After a ticket is purchased, the airline also sends several emails reiterating what the customer gets with it and that they can change to a regular-economy fare within 24 hours of their purchase.

(Screenshot)

"We tried to make it very clear throughout the process that the customer knows they are choosing the basic-economy fare," a United spokesman told Business Insider.

The spokesman wouldn't comment on what kind of customer feedback United had received since finishing the domestic rollout because he said it was too early to have a clear consensus. However, he said the airline had seen improvements in its boarding process because of fewer carry-ons.

United isn't the only carrier offering basic economy that's aiming to communicate clearly to consumers how the new fare class works. Delta Air Lines and American Airlines have also launched basic-economy tickets and issue alerts to customers before purchase outlining what the new fare class includes.

Despite any setbacks, though, the airlines see the new class as a way to boost revenue. United's president, Scott Kirby, told Flight Global earlier this month that segmentation, in general, could add as much as $1 billion to the company's bottom line.

NOW WATCH: How often airlines involuntarily bump passengers (United isn't the worst)

More From Business Insider

• Paramedics are under fire for their handling of a dying woman on an American Airlines flight
  

• The government says that the Tesla Model X is an extremely safe SUV
  

• 4 of the worst airports in the world are British