A fuel surcharge on flights is the line on your receipt that looks official, sits next to the real taxes, and isn't one. Airlines add it themselves. It started years ago when jet fuel spiked and carriers wanted a way to raise prices without touching the advertised base fare. Fuel is cheaper now than it was then, but the surcharge mostly stuck around, because once a line item is on the receipt it's a lot easier to keep than to remove.
The confusing part is that it's bundled into the total you pay for a normal cash ticket. When you buy a seat outright, the fare, the taxes, and the surcharge all add up to one number, and that number is what you compare against every other option. So on a regular booking the surcharge isn't really costing you anything extra to worry about. It's already baked into the price you're weighing, the same way the bag and the seat you'll end up paying for are part of the real cost even when the ad shows a smaller figure.
Why the fuel surcharge on flights matters most on award tickets
Where it actually bites is points and miles. When you redeem an award ticket, the miles cover the fare, but you still pay the taxes and fees in cash, and on a lot of airlines the fuel surcharge rides along in that cash portion. That's how a "free" long-haul flight ends up asking you for a few hundred dollars at checkout. Two award seats on the same route, same cabin, same miles, can have wildly different cash costs depending on which airline's metal you book and which frequent-flyer program you book it through. Some carriers pass almost no surcharge. Others pass a lot.
Can you avoid it?
On a cash ticket, not really, and there's not much point trying, since it's part of a total you'd compare anyway. On an award ticket, sometimes. Routing through a different airline in the same alliance, or booking the same flight as a partner award through a program that doesn't collect the surcharge, can cut the out-of-pocket cost by a surprising amount. It takes some digging, and it only pays off on the expensive long-haul redemptions.
For everyday cash fares, we don't itemize surcharges and neither should you. What we do is send you a few real options side by side each morning with the all-in price, surcharge included, so you're always comparing the number you'll actually pay. The line on the receipt makes for good trivia. The total is the only part that decides anything.