"Airlines are looking for any way they can to reduce fuel burn within the limits of safety," said Paul Steele, director of the environment at the International Air Transport Association (IATA).
Here's what some carriers are doing:
US Airways Group Inc. has removed ovens from 208 Boeing and Airbus planes on flights that do not serve hot meals. Philadelphia's largest airline also has scaled back the size of its in-flight magazine, and pulled in-flight entertainment systems from 200 planes, estimated to save 500 pounds of fuel burn on most flights.
American Airlines, Delta Air Lines Inc., and some others taxi to and from gates using one engine to conserve fuel.
Southwest Airlines Co., Delta, and American have put wing-tip devices - called winglets - on aircraft to reduce drag and fuel burn.
American is replacing 19,000 heavier catering trolleys with lightweight versions, trimming 124 pounds from the average aircraft. Continental and Delta have switched to lighter meal carts, a move Delta says saves 2.2 million gallons of fuel annually.
Japan Airlines Corp. serves meals in Business and First Class on lighter porcelain crockery and shaved the size of its cutlery, reducing the weight 2 grams per spoon, said spokeswoman Sze Hunn Yap. Though that might not seem like much, a 747-400 plane flying from Tokyo to New York carries 950 forks and 1,900 spoons, according to the airline trade group IATA.
Air France-KLM S.A. took 35 different steps to shed aircraft weight, including using new plastic drink cups that are 3.5 grams lighter and estimated to save 57 tons of fuel a year based on 1,700 daily flights, said Francoise Barrard, director of flight support.
Many planes are carrying less potable water for lavoratories.
"Delta spent a lot of time to understand exactly how much water is needed on a flight based on its duration," said spokesman Kent Landers. "In the past, a plane would have been loaded to its maximum capacity."
Similarly, JetBlue Airways Corp. looked at how much passengers eat and drink on flights, and now loads only the amount that will be consumed. Not storing extra provisions eliminates 100 pounds.
JetBlue has removed one row, or six seats, on every A320 aircraft and reconfigured the remaining 25 rows, which increased legroom and cut 904 pounds from the 42.4-ton plane.
Delta, Air France, and JetBlue retrofitted planes with new passenger seats made of lighter, plastic-based composite materials instead of metal.
Removing "unnecessary items," such as phone equipment, galley tables, magazine racks, and razor outlets in restrooms, saves American an estimated 1.1 million gallons of fuel a year.
To slim down each plane in its cargo fleet by 150 kilograms, Japan Airlines has stopped painting the planes' exteriors.
Aluminum liners in cargo containers have been replaced with new materials, reducing the weight, which Delta estimates will save it 1.3 million fuel gallons a year.
To further conserve fuel, airlines are planning more efficient flight paths and direct routes that shorten flight distances; regularly cleaning jet engines; and adopting "continuous-descent approach" landings at airports that allow planes to descend continuously from cruising altitude, reducing the use of engine thrust and, consequently, the amount of fuel used.
Representatives of the world's airlines met in Malaysia this month and agreed to reach "carbon-neutral growth" by 2020, as well as test alternative carbon-free biologically derived fuels.
Biofuel derived from algae and jatropha plants powered a test flight in January by Continental, the first by a commercial carrier in North America.
Continental said the fuel blend performed "as well as or better" than traditional jet fuel and was estimated to reduce greenhouse gas emissions 60 percent to 80 percent.
"These fuels are perfectly usable for aviation," IATA's Steele said. "The big question mark is: How cheaply can they be produced and how different will they be at the end of the day from the prevailing oil price?
"The big benefit is they have a significantly lower carbon footprint than jet fuel," he said. "It's better for the environment."
Contact staff writer Linda Loyd at 215-854-2831 or firstname.lastname@example.org.