Slow Down to Achieve Fuel Efficiency

With jet fuel skyrocketing, airlines are having a tough time and are trying every trick on the book to stay profitability. Airlines are taking different measures including raising fares, adding fuel surcharges to tickets and charging extra for a second checked bag. In recent weeks, several smaller airlines have filed for bankruptcy protection blaming high fuel cost. Jet fuel cost is also blamed for the sharp quarter losses by some air carriers.

From the beginning of commercial flight, airlines came to know the different steps to optimize fuel consumption. Aviation terms such as optimal altitude, optimal cruise performance, optimal flight path, optimal flight speed, etc. are no stranger to aircraft makers (Boeing and Airbus) and commercial airline pilots alike. For years, aircraft manufacturers test their products for fuel economy. Aircrafts' operating manuals include tables and charts helping pilots to determine the optimal cruise performance based on aircraft's gross weight, flight distance, air speed and cruising altitude. Today, airlines e.g. WestJet Airlines, United Airlines, etc., automate this once manual process with on board navigation and software systems.

In practice, airline pilots may find it difficult to achieve aircraft's optimal flight performance in crowded airspace, where airplanes' air speed, heading, speed restrictions and cruising altitude are orchestrated by air traffic controllers.

Jet engine's fuel efficiency improves as an aircraft travels through thin air mass. When an aircraft flies at high altitude, it has less drag in flight and consumes less fuel. But, trip distance is normally the governing factor in determining the optimal altitude for a specific flight if weather, air traffic and wake turbulence are of no factor in flight.

To be cost effective, airlines go great distance to make every drop of jet fuel counted. Airlines require their pilots to taxi at airport tarmac with only one engine. Airlines keep the external surfaces of their aircrafts clean so as to reduce drag in flight.

As an airplane moves through the air, it generates the hazardous wing tip vortices that trail behind the aircraft. Continental Airlines equips its fleet of Boeing 737, Boeing 757 and regional jets with winglets aimed to break up the harmful wing tip vortices that serve to increase the drag on the airplane and to lower its fuel efficiency at the same time.

Aircraft's fuel consumption is directly proportional to its gross weight. To be fuel efficient, an aircraft carry only the payloads that are necessary for the trip. In the seventies, Eastern Airlines stripped off the paint from the fuselage of its aircrafts to reduce an aircraft's gross weight by 500 pounds. With this in mind, have you ever asked why American Airlines' planes are left unpainted? Today, airlines reduce the weight of their airplanes by using lighter trolleys and cargo containers and by carrying enough water on each flight.

Today, we learned U.S. airlines have ordered their pilots to slow down in order to reduce fuel consumption. Southwest Airlines, JetBlue Airways and Northwest Airlines claim to have multi-million dollar savings by adding few minutes to each flight. The extra flight time is added to existing flight schedules or absorbed into the extra time already built into schedules for taxiing and traffic delays.

Not every airline slows down to conserve fuel. For one thing, flying below a certain speed can actually increase an aircraft's fuel consumption. Some airlines feel working with aircraft gross weight is a better approach to fuel efficiency.

As explained earlier, optimal fuel efficiency can only be achieved by carefully maneuvering the aircraft's gross weight, flight distance, air speed and cruising altitude.

By slowing down an aircraft alone, airlines can definitely save jet fuel. However, I feel airlines can achieve better results with fuel efficiency if they followed United's lead and invested in on board avionics that have a good handle on all factors (airspeed, cruising altitude, gross weight and distance).

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