"Flight distance" refers to the length or distance covered by a flying object, such as an aircraft or a bird, from its starting point to its destination. Full definition
The number of miles passengers earn depends on flight distance, cabin choice, ticket type, and elite status. (upgradedpoints.com)
You must use 2 airlines, and your total flight distance must be less than 10,000 miles. (upgradedpoints.com)
The AAdvantage rewards chart will not change for flight distance, meaning if you need to redeem miles for a domestic flight, try to make it a long domestic flight. (valuepenguin.com)