FAA Aircraft Dispatcher (ADX)Flight Planning and PerformanceHard
A dispatcher selects the Long Range Cruise (LRC) speed schedule for a flight instead of the maximum specific range speed. What is the primary reason for this selection?
- ALRC provides approximately 99% of the maximum specific range at a somewhat higher airspeed, reducing flight time with only a minimal fuel penalty.
- BLRC always uses less total fuel than the maximum range speed for the same distance.
- CLRC produces the lowest true airspeed possible for any given fuel flow setting.
- DLRC is a Part 121 regulatory requirement for all flag operations regardless of route.
Show answer & explanationAnswer & explanation
Correct answer: A. LRC provides approximately 99% of the maximum specific range at a somewhat higher airspeed, reducing flight time with only a minimal fuel penalty.
Long Range Cruise speed is defined as the speed slightly above maximum-range speed that still achieves about 99% of the maximum specific range, but with a higher true airspeed, reducing trip time with only a small fuel efficiency penalty.
Why the other options are wrong
- B. LRC uses slightly more fuel than max range speed for the same distance; it doesn't use less.
- C. LRC produces a higher, not lower, airspeed than max range speed.
- D. LRC is an operational choice, not a specific regulatory mandate.
Long Range Cruise (LRC)
A cruise speed schedule providing about 99% of maximum specific range at a higher true airspeed than max range speed, reducing flight time with minimal fuel cost.
- LRC speed is higher than max range speed
- Provides ~99% of max specific range
- Commonly used operationally to balance time and fuel efficiency
Memory trick: LRC = '99% range for a little more speed' — the best of both worlds.