Buying plane tickets online isn't like other shopping experiences on the Web -- there's no time for you to linger on a decision if you see a fare priced the way you like. Pull the trigger right away, or suffer the possibility of seeing a major price spike the next time you return to the computer. 

But starting today, British Airways is offering a new feature on that lets you hold a ticket -- and the fare you were quoted -- for up to 72 hours. You'll pay $10 for the service, but the fee is applied to the price of your ticket once you buy it. (You lose your $10 deposit if you don't.) 

Drew Crawley, British Airways chief commercial officer, said in a statement, "There's nothing more frustrating than seeing a great flight price but not being able to book it straight away, either because you may need to get the time off work or check it's OK with family or friends -- then coming back and finding there are no seats left or the price has changed."

I'd have to agree -- I've lost many a good fare this way. 

The new hold option is the result of a joint project between British Airways and Iberia, both owned by International Airlines Group.  It applies to reservations for all flights operated by British Airways, including code-sharing flights, Iberia, Iberia Express and Air Nostrum. This includes any combinations of flights of British Airways and Iberia, as long as they are on the same ticket. But it is not available on flights that are within 21 days of departure. 

I wasn't thrilled to see that several destinations, like Mexico, Dominican Republic and St. Lucia, are excluded. See the full list below.

excluded These destinations are excluded from the 72-hour hold option. Photo: British Airways

United Airlines offers a similar service called FareLock that also lets you a hold a ticket for up to 72 hours, though its fee can fall between $5 and $20, depending on the itinerary you're holding. (And the fee is added, not applied, to the price of your trip.)

I've had good luck with it: I recently used United FareLock to purchase a ticket to Cabos San Lucas, and when I was ready to buy after three days, I noticed that United was quoting a higher price. It saved me about $75. Score!