Using more efficient environmental procedures for airline operations is one of the best ways to reduce environmental pollution, burn less fuel, and save money. There are numerous models, tests and policies being formulated throughout the world that create better environmental procedures. Here are a few samples that are being used at all phases of your flight.
It begins with starting engines. Many airlines have a policy to start and taxi out to the runway on one engine. Obviously, not turning the other engine on will save fuel. Starting one, two, or more engines (depending on the aircraft you are on!) depends on the weight of the aircraft, conditions on the ramp, and taxiways (wet, snow, ice). Also included are outside temperatures and the blast effect of engines while starting the taxi out. A relatively new idea that has been put forth and tested, is towing an aircraft out to the runway by a tractor in order to save the big jet engines from burning fuel on a long taxi.
After takeoff, aircraft usually climb to altitude at a precomputed speed that is most efficient depending on your aircraft weight and requested altitude. For jet aircraft, higher altitude is better because jet engines burn more efficiently at higher altitudes. Therefore, simply allowing departing aircraft to maintain a continuous climb as much as possible would burn less fuel and reduce emissions and noise. Present use of the airspace is gradually being improved with better equipment and design. Departure and arrival rates also must jive with each other because of safety considerations. With a finite airspace, departing aircraft must be kept low on a frequent basis to allow a sufficient safety margin for arriving and descending aircraft.
While in cruise, speeds are once again precomputed based on optimum altitudes, winds, the weight of the aircraft, and the flight schedule. This is where experience comes into play once again. For example, if we are ahead of schedule we would slow down. Why? If we get to our destination airport too early (especially one with limited gates) we would have to sit on the ramp and wait for the gate to open. We would slow down to conserve fuel and arrive closer to the scheduled time. Another example - if we are going from west to east in the winter with a strong Jet Stream , especially at higher altitudes, then we climb as high as our weight can allow it (if it is a smooth ride!). This allows our engines to burn more efficiently, and reduce our power because the strong tailwind is pushing us along and still giving us an ontime arrival. Burning less fuel and arriving ontime is a win-win situation.
On arrival, as on our departure, traffic increases around the airport area and arriving flights are usually slowed down. Constant Descent Approaches (CDAs), along with various other approaches (to be discussed in another section), is among the many environmental procedures being tested for the arrival phase of your flight. Flying a CDA means that once your descent begins at an initial high altitude, the throttles are at idle, until a couple of hundred feet above the ground. Approaches and landings, probably on average, burn more fuel than any phase of flight. This is because during the arrival phase, you are usually flying below 10,000 feet. You are being vectored for the landing runway, and throttles are moving forward and back to slow down or speed up as requested by the air traffic control (ATC). Less efficient engines at this low altitude and constant throttle movement means more fuel burned, more emissions, and more noise.
These are some of the environmental procedures that are being used now and for the future, that will reduce environmental pollution and make your flight "greener".Environmental Procedures back to Green Aviation