A dispatcher is planning a route over mountainous terrain where the MEA is 16,000 feet due to peaks of 14,500 feet MSL. The twin-engine aircraft's single-engine service ceiling at the planned weight is only 12,000 feet. What must the dispatcher do to comply with engine-out obstacle clearance requirements?
- APlan the route as filed, since single-engine ceiling only matters at cruise altitude
- BFile the flight IFR and rely on ATC vectors if an engine fails
- CNo special planning is needed as long as the flight remains above 12,000 feet in normal cruise
- DSelect an alternate enroute course or reduce weight so the single-engine service ceiling meets or exceeds the required obstacle clearance altitude along the route
Show answer & explanationAnswer & explanation
Correct answer: D. Select an alternate enroute course or reduce weight so the single-engine service ceiling meets or exceeds the required obstacle clearance altitude along the route
Dispatchers must ensure that in the event of an engine failure anywhere along the route, the aircraft can maintain terrain/obstacle clearance while operating on the remaining engine(s). If the single-engine service ceiling is below the required MEA, the route must be revised (e.g., an escape route with lower terrain) or weight reduced so the single-engine ceiling meets the obstacle clearance requirement.
Why the other options are wrong
- A. Single-engine ceiling matters for the entire route in case of engine failure, not just cruise.
- B. ATC vectors do not guarantee terrain clearance capability with one engine inoperative.
- C. Ignoring the shortfall between service ceiling and MEA is unsafe and non-compliant.
Engine-Out Enroute Terrain Clearance
Dispatchers must verify that an aircraft's single-engine service ceiling allows safe terrain clearance along the entire route in the event of an engine failure, planning escape routes or weight reductions as needed.
- Compares single-engine ceiling to route MEA/obstacles
- May require an engine-out escape route over lower terrain
- Directly affects maximum allowable takeoff weight on mountainous routes
Memory trick: One engine down, terrain still counts — plan the escape.