Eurocontrol data shows aircraft fly higher

In their flight plans, aircraft request to cruise at an altitude (‘flight level’) that’s most efficient for them, so that they burn less fuel. When airspace is congested, they might request lower or be kept lower by air traffic management. A graph supplied by Eurocontrol graph shows how requested cruise levels have increased over the last 25 years: in September 1995 only 6% of flights requested to cruise above flight level 350 (FL350, approximately 35,000 feet), by September 2021 40% of flights did. Two advances in aircraft technology have driven cruise levels higher over this period. First, altimeters improved to