On today's commercial flights, extras tend not to be advertised, but they're often worth asking for. Here are little-known perks available to every passenger, from economy to first class.

See 10 Ways to Score Secret Airline Perks

Next: Y-Ups and Q-Ups

Get AOL Travel Deals
+ U.S. Vacation Deals
+ Adventure Travel Deals

Y-Ups are special codes on first-class airfare which indicate that the seat can be assigned to those looking to upgrade from economy. To find one of these secret fares, go to your preferred airline's Web site. Search the first-class seats on the flight you want to take. If any of those seats are tagged to a code like Q***UP, write that code down. Then, search for an upgradeable coach seat (some airlines don't allow upgrades for super-cheap coach fares) and write down that code, too. Finally, call the airline--they'll usually waive the telephone service fee for frequent fliers, if you ask--and request that your coach seat be upgraded to the first-class seat. For the price of coach, of course.

Next: Free Champagne

On Air France, everyone's treated to a bit of bubbly on every flight the carrier operates. Complimentary champagne--yes, from the region of the same name, is served to passengers in economy, business and first class.

Next: First-Class Food

Get AOL Travel Deals
+ Domestic Flight Deals
+ U.S. Vacation Deals

While nearly every airline is now charging for in-flight meals -- Continental is the one holdout -- the good news is that some have begun offering quality eats and drinks for a minimal price. On Delta's flights, guests have the option of choosing from a Todd English-designed menu, which includes New York-style pastrami on a pretzel roll with mustard slaw, Swiss cheese and lettuce -- an obvious upgrade from the traditional ham and cheese on white.

Next: Carbon Credits

Get AOL Travel Deals
+ U.S. Vacation Deals
+ Adventure Travel Deals

Feeling guilty about racking up those gas-guzzling miles? Virgin America now allows passengers to buy carbon offsets on flights through the nonprofit Carbonfund.org. A donation of $5 offsets 2,500 miles; $10 offsets 5,000 miles. Currently, offsets are being used to fund the reduction of tailpipe emissions in large trucks and to fund biodigesters, machines that capture methane before it's emitted into the environment, converting it into liquid fertilizer.

Next: Concierge

Get AOL Travel Deals
+ Domestic Flight Deals
+ Adventure Travel Deals

Looking for a flight attendant with the knowledge of a travel agent? That's what Air New Zealand aims to provide with its in-flight concierge service, available to all passengers. These concierges offer practical assistance with airline processes and travel arrangements, and they have specialized knowledge of the airline's destinations -- they'll personally recommend local restaurants, shopping, must-see sights and other insider info.
More Secrets to Airline Perks

Get AOL Travel Deals
Cruise Deals
Disney Vacations
Honeymoon Travel
International Travel
More Travel Deals