The future of air travel

From CNN:

Kroo believes the way we fly planes may change. Currently all commercial airliners cruise at speeds of around Mach 0.85 (85 percent of the speed of sound). Kroo believes in the future planes may slow down, say from Mach 0.85 to Mach 0.75.

He also believes planes could fly at lower altitudes because of concerns that contrails affect the atmosphere. Other environmental impacts would also be reduced. Nitrogen oxide emissions, unburned hydrocarbons and water vapor all have an impact strongly related to how long they stay in the atmosphere: lower altitudes help reduce this.

"It's uncertain, but people are actively planning flight paths at lower speeds and altitudes. The sky in the future may not be filled with white lines," Kroo said.

This would mean very efficient airplanes flying at slightly slower speeds -- a small change in convenience but a profound reduction in environmental impact. A reduction in fuel burn of 50 percent is not out of the question, according to Kroo.

More here.