Study says changes in air traffic patterns could cut fuel costs and greenhouse gas emissions

Airlines could save money and cut emissions by adjusting the rhythm of transatlantic flights. @bberwyn photo.

Changing flight intervals could save $10 million per year

By Bob Berwyn

Tweaking flight paths across the Atlantic could yield huge savings in fuel costs and help cut airline greenhouse gas emissions.

“If the lateral separation between the aircraft can be reduced, they can be spaced closer and remain more in line with their optimum flight paths. Overall, this would produce fuel economy as most aircraft save fuel at higher cruise altitudes,” said Antonio Trani, director of Virginia Tech’s Air Transportation Systems Laboratory and a professor of civil and environmental engineering.

Trani and fellow researchers reached their conclusions after studying flight information and fuel consumption for air traffic in the North Atlantic oceanic airspace. The research is part of the Future Air Navigation System started in the 1990s that focused on communication between aircraft and air traffic control services, conducted for the Federal Aviation Agency.

Commercial traffic represented the majority of the operations studied by Trani in the North Atlantic space used by Canada, Denmark, France, Iceland, Ireland, Norway, Portugal, the United Kingdom, and the United States. In this space, the aircraft are subjected to large separation standards due to safety considerations, and these criteria can cause large vertical deviations that call for greater fuel usage.

The modeling showed that, if  aircraft could fly at a closer spacing of five minutes apart instead of the current 10 minutes, the fuel savings would be huge. The current spacing is based on safety considerations.

Most of the traffic in the airspace they studied took flies along five to seven nearly parallel oaths. The exact location of these tracks is updated twice a day, one for eastbound and one for westbound traffic, and according to projected wind and meteorological conditions.

“This was an unprecedented study, capturing information for 44 major airlines, representing 81.6 percent of the North Atlantic Systems operations and 88.2 percent of commercial operations,” Trani said.

To keep air traffic safe, planes would have to be upgraded with new high-tech communications capabilities because most of the North Atlantic airspace is out of range of very high frequency and radar.

Currently, the majority of communications take place using high frequency voice that is subject to disruption, atmospheric effects, ambiguity in accents, frequency congestion, and a third party relay between pilots and controllers,” Trani said.

Out of about 2,152 commercial airframes operating in the North Atlantic airspace, Trani estimated that some 838 airframes would need some level of retrofit, totaling an estimated $464 million (based on 2010). The range for a single aircraft would be significant – anywhere from $50,000 to more than $1 million depending on its original level of aircraft equipment.

Trani’s group estimated annual fuel benefits if changes occurred this year, moving to the five minute intervals, at $10 million. If, as he suspects, the time could be moved to two minute intervals, the savings would jump to $37,273, 498. Recently this analysis has been applied to Pacific Ocean flights by Trani and his postdoctoral assistant Tao Li with potential fuel savings of $35 million annually.


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