SMACFUM is a procedural memory aid used in multi-engine flight training to sequence the critical actions following an engine failure, particularly during or after takeoff. While the exact letter assignments vary modestly across training organizations and aircraft types, the mnemonic typically addresses: Situation (aircraft control and recognition of the failure), Mixture (advance to rich), Airspeed (establish Vyse — the blue-line airspeed that delivers best single-engine rate of climb), Cowl flaps (close on the failed engine to reduce drag), Fuel (boost pump on, switch to fullest tank), Undercarriage (retract to eliminate drag), and Magnetos or Master (as applicable to secure the failed engine). The sequence is designed to guide pilots from the immediate instinctive response — maintain aircraft control — through drag reduction and performance optimization on the remaining engine, culminating in securing the failure and preventing further damage or fuel feed issues.
The difficulty students encounter with SMACFUM reflects a structural challenge in multi-engine training more broadly: the mnemonic must be executed under high workload, in a degraded performance environment, with asymmetric thrust creating adverse yaw and roll tendencies simultaneously. Unlike many single-engine emergency checklists, the multi-engine engine-failure flow requires the pilot to complete steps in a specific priority order because sequence errors — such as retracting gear before establishing a positive climb rate, or feathering the wrong propeller — can be immediately catastrophic. This is why multi-engine checkrides under FAA Practical Test Standards place heavy emphasis on demonstrating the correct memory-item flow before referencing any checklist, and why flight instructors universally emphasize chair-flying and verbalization as study methods.
For working pilots transitioning from single-engine certificates to multi-engine operations — including those pursuing Part 135 or corporate Part 91 positions requiring MEI or MEL privileges — fluency with engine-failure memory items is not an academic exercise. Real-world multi-engine emergencies, particularly EFATO (engine failure after takeoff) scenarios at or below Vmc or below single-engine service ceiling, leave little margin for hesitation. NTSB accident data consistently shows that loss of control following engine failure in light twins is often attributable not to the failure itself but to pilot delay in establishing Vyse, failure to identify the correct engine, or inappropriate rudder application — all areas that SMACFUM, properly internalized, is designed to prevent.
The broader training context is significant: the light twin fleet operating under Part 91 and Part 135 includes a wide range of aircraft from piston twins like the Beechcraft Baron and Piper Seneca to turboprop platforms, and the fundamental engine-failure discipline taught through SMACFUM scales directly to those higher-performance environments. Operators and chief pilots evaluating candidates for multi-engine positions routinely assess not just whether an applicant can recite the mnemonic but whether they can execute it smoothly under simulated stress in the aircraft or a qualified simulator. Students struggling with procedural mnemonics are well-advised to practice verbalization in sequence daily, simulate the cockpit layout physically, and connect each step to the aerodynamic or mechanical rationale behind it — because understanding why each action appears in its specific position in the sequence substantially improves retention and execution under pressure.