But all is not lost. It's still possible to get something for nothing -- free or cheap upgrades to business or first class.
If you follow our travel experts' advice, you may be winging your way to better service and more leg room. As it turns out, it's possible, at least sometimes, to fly frugal and first class.
John DiScala, who runs travel website JohnnyJet.com, agrees. "I'm amazed at how poorly (travelers) treat gate agents and flight attendants."
DiScala, who visits about 20 countries each year, sweetens the pot -- literally. "Every time I fly I bring a box of chocolates," usually given to a gate agent or a superintendent.
Upgrades are sometimes a case of "who you know," DiScala says. If a gate agent recognizes you, the chance of an upgrade takes off, DiScala says. So get to know one or two. "A gate agent can do anything," he says.
If it doesn't happen before you board, then be a good sport about being in coach, says Paddock. Your upgrade request to harried flight attendants preparing for takeoff will be "the biggest turnoff ever."
If coach is overbooked, but there are empty seats in first class, some passengers may receive an upgrade. It's only natural the crew would turn to someone who looks like they belong there.
"No crew member is going to want to upgrade you if you're dressed in your pajamas or yoga wear," she says. "It can make other people resentful," if they paid big bucks to travel in first class or business class.
That doesn't require women to hike down the ramp in spike heels or guys to don a Windsor knot. Just dress nicely and neatly, as opposed to the "super casual or sloppy" manner common today, Paddock says.
Gate agents tend to feel less pressured early in the day, says Lauren Sullivan, the North American site editor for CheapFlights.com. They may be more inclined to dole out upgrades if available.
DiScala always checks his flights 24 hours before departure to gauge how full they may be. If a flight is completely oversold and the airline is looking for volunteers to catch a later flight, that's a perfect time to negotiate for an upgrade, he says. Furthermore, a weather delay can work to your advantage if you're rebooked on another flight, and the only seats available are at the front of the plane.
And don't forget to play an emotional trump card. Let the airline workers know if you're celebrating a special event like your honeymoon, Sullivan says.
Travelers with "status" are more likely to receive a free upgrade than the average frequent-flier member, says Sullivan.
By being loyal to a particular airline, your odds of being upgraded by that carrier gain altitude, says Sullivan. She encourages travelers who want to earn elite status to stick with the main carrier or carriers at the airport they most often use.
"The reward will work both ways. The people who fly the most are rewarded the most," she says.
If you're willing to cough up a bit of cash, or use your frequent-flier miles, you also may be able to get upgrades at cut-rate prices.
If seats in business or first class are vacant, they may be offered to economy-class travelers at check-in. Frey recently paid $90 for an upgrade on a flight from El Paso, Texas, to Miami. "You have to be on the lookout when you check in," he says.
Another option is using frequent-flier miles. While you may encounter turbulence booking a flight using miles, it's often easier to book an upgrade, Frey says. The miles are "almost like currency."
Whatever your strategy for trying to earn an upgrade, Frey says the most important thing to keep in mind is, "There's just not as many seats to go around these days."
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