Most major airlines have figured out the cash cow of selling some of their better seat assignments. Now British Airways is going them one better, by in most cases, charging for ALL pre-assigned seating.

As usual, this change is being announced as “giving you more control.” For the general public, British Airways offers pre-assigned seats only for full fare tickets. All passengers traveling on discounted tickets, even discounted business-class tickets, must wait until 24 hours in advance. And that assigned-seat option is only available to passengers who check in online.

Starting Oct. 7, any passenger can get a pre-assigned seat at any time, up until the online check-on opens — If they pay for it.

The cost for a seat assignment on a transatlantic flight in economy or premium economy will be $30 each way. Even more surprising, passengers on discounted business-class tickets will pay $90. Worse, the charges are per segment that will make a round-trip connecting flight end up costing $360 more for assigned seats in business class.

For flights within Europe the seat-assignment cost will be $30 business, and $15 economy. Passengers on full-fare tickets will still be exempt, as will Premier, Gold and Silver level Executive Club members.

For exit-row seats, the costs are even higher — $75 each way, and they are available only ten to four days prior to departure. Only top-level frequent fliers will be exempt from that fee, along with clients of top British Airways corporate accounts and a very small number of travel agents.

Curiously enough for an airline that has so strongly encouraged all its passengers to check in online, the new paid seat assignments will, at least at the beginning, be only available by phone.

While the British Airways site does not mention this (no doubt as other airlines don’t), the seat assignment fee will be nonrefundable. No word yet of the seat-assignment charge refundability rules for a passenger who simply makes a date change on a ticket and pays a penalty. (My expectation would be yes.)

No U.S. carrier has started charging for every seat assignment, yet. But no doubt they will be watching the British Airways experiment with interest. If it works, and the reaction is mostly positive, or at least doesn’t result in a drop in bookings, look for the same policy here.