CHARLOTTE, N. C. — Will airlines soon charge you extra for a premium seat when you buy your plane ticket?

Or stick you in a middle seat if you refuse to pay more?

US Airways CEO Doug Parker recently said he believes some fliers would pay more in advance for, say, aisle seats in coach at the front of the cabin. The airline doesn’t yet have the technology to do that, though it soon could.

The move to add fees on seats at the time of purchase could be the next frontier in what US Airways calls “a la carte” pricing — the charging of fees for perks that used to be included in the price of a ticket, such as food, blankets and checked bags.

Other airlines have embraced similar fees. US Airways already allows customers to pay between $5 and $30 per flight to reserve aisle and window seats in the front of the coach cabin when they check in, but not when they buy.

In a recent conference call with analysts, US Airways President Scott Kirby said the technology could be in place by the middle of next year to charge extra at the time of purchase.

“The reality is, sitting in the first row of coach on the aisle is a better seat than the middle seat next to the lavatory in the back of the airplane, and today we charge exactly the same price for those,” Kirby said at the time. “So to allow customers to differentiate between those two seats is something that we’re eventually going to do, I believe.”

Parker said that although some customers may not like extra fees, the airline has seen no drop-off in bookings because of them. He said the shift to a fee-based model generates important revenue for airlines, which continue to lose money because of the economy.

The airline estimates the fees will generate $500 million a year. Its overall revenue last year was $12.2 billion.

And Parker said other industries routinely incorporate fees into their business models. The Charlotte hotel he stayed in charged him $3 or $4 for a soda from the minibar, he said.