While a controller must be able to recognize weight class, speed, and climb rate for each aircraft type, he or she must consider several additional factors that affect an aircraft's performance, including:
- Weather conditions – will impact aircraft performance. Increases in temperature generally result in lower aircraft performance. For example, a JAN departure that climbed above sector 67 on a cold day may need a point out on a hot day.
- Engine performance – may vary within an aircraft model. For example, various models of B737s have markedly different performance characteristics due to variations in engines. B738s generally climb much faster than B731s and B732s.
- Load (Weight) – affects the performance of all aircraft types. You might expect aircraft traveling long distances to have large fuel loads which decrease performance in the initial stages of flight.
- Aircraft configuration – may impact performance during phases of flight. For example, descent and arrival phases of flight may have flap and gear configurations that limit performance.
- Company policy – may influence performance ranges. For example, fuel cost/fuel conservation issues may cause pilots to fly aircraft at slower speeds and lower climb rates.
- Schedule considerations – may cause pilots to fly aircraft at other than expected speeds in order to meet schedules.