Plain English Meaning

The speed the aircraft's computer works out to give the cheapest overall flight, taking into account both how much fuel costs and how much time costs the airline.

Full Definition

ECON speed is an economy cruise speed calculated by the flight management system (FMS) that balances fuel cost against time cost to produce the most cost-effective speed for a given flight. It is derived using a cost index entered by the operator, which weighs the value of time relative to the value of fuel.

Context Anchor

Seen on flight management system pages and in VNAV planning, especially when the aircraft is calculating climb, cruise, or descent speeds.