Up to half the aircraft that land at Los Angeles International Airport each day now use an arrival technique that saves fuel and reduces noise and air pollution in neighborhoods along the eastern approaches to the nation's fourth-largest airport, the Federal Aviation Administration has announced.
Officials said Thursday that the technique also increases the safety of landings, one of the most critical phases of a flight.
The procedure, known as continuous descent approaches, allows airplanes to glide into LAX under minimum power instead of making a string of stair-step descents that require pilots to rely on their engines to repeatedly speed up and then slow down to level off. The FAA estimates that on average, about 300 to 400 of the 800 aircraft that land daily at LAX use continuous descent.
"It's like taking your foot off the gas at the top of a hill and just gliding straight into the airport from 18,000 feet on a smooth, controlled path to touchdown," said Walter White, an FAA manager who headed a team that developed the procedure.
Although more study is required, FAA officials conservatively estimate that use of the technique at LAX alone saves airlines at least 1 million gallons of fuel annually and reduces carbon dioxide emissions, which have been linked to global warming, by about 18 million pounds a year.
In addition, there are indications that the procedure reduces noise in the communities beneath the flight paths. At Louisville International Airport in Kentucky, United Parcel Service has reported a 30% reduction in aircraft noise within 15 miles of the airport.
During flight trials in May 2008, Delta Airlines officials said that noise reductions of 3 to 6 decibels were achieved within 25 miles of Hartsfield-Jackson airport in Atlanta. Depending on the aircraft, Delta also reported that it cut carbon dioxide emissions by 200 pounds to 1,250 pounds and saved 10 to 60 gallons of fuel per arrival.
"For everyone in the L.A. Basin, this is a help, a total win-win. You've got the fuel savings, the noise reductions and the attendant reduction in contamination. That in itself is important because airplanes are a major source of pollution," said Denny Schneider, an airport activist and member of the Alliance for a Regional Solution to Airport Congestion.
In addition to carbon dioxide, jet engines emit harmful nitrous oxides, a major cause of smog, and fine particles of soot, a health-threatening pollutant that is largely uncontrolled. The emissions have become a concern in airport communities worldwide, including those around LAX, where an air pollution study is underway.
After more than a decade of research, the FAA implemented continuous descents at LAX in December 2007 on one of the eastern approaches. Since then, the agency has converted the other two eastern routes to the procedure, making LAX the only airport in the nation to have such a broad application of the technique.
The routes follow the same flight paths as the conventional approaches and pass over San Bernardino, Ontario, Chino, Diamond Bar, Whittier, Bell Gardens, South Gate, Los Angeles and Inglewood, communities that have long been concerned about overflights.
Inbound planes reduce power and begin their glide about 60 to 80 miles east of LAX. FAA officials say that onboard computers calculate the best path of descent based on the aircraft's performance abilities. No special equipment is required, so virtually any aircraft can use continuous descent.
The next step is to develop the procedure for the southern and northern approaches to LAX, which has become a model for other airports around the country that are exploring the technique. Ultimately, White said, the FAA wants to use the procedure for all flights coming into Los Angeles.
In addition to fuel savings and environmental benefits, airline industry officials say continuous descents can improve safety during landings. Approaches are simpler because pilots no longer have to descend and level off repeatedly and they don't need to communicate as much with air traffic control to obtain clearances and directions.
"You've got the ability to stabilize the airplane because you don't have the stop-and-go procedures. Less radio communication is required, which eliminates chatter and the confusion that can go with it," said Basil Barimo, vice president of operations and safety at the Air Transport Assn., a national trade organization that represents carriers.
Compared with standard arrival procedures, continuous descent approaches require about half the radio communications between pilots and air traffic controllers, FAA officials say.
Eventually, Barimo said, continuous descent will be used across the country.