An engine-inoperative (OEI) approach and landing is one of the most demanding maneuvers a multi-engine pilot will practice. The combination of asymmetric thrust, degraded climb performance, and the psychological pressure of flying a crippled airplane on final approach creates a high-workload environment where poor planning or late decisions can quickly become fatal. The FAA Airplane Flying Handbook (FAA-H-8083-3C, Chapter 13) dedicates significant attention to this topic because the approach and landing phase—not the initial engine failure—is historically where OEI accidents cluster.
Understanding the engine-inoperative approach begins long before the runway threshold. From the moment a pilot confirms an engine failure and determines that a landing is necessary, every subsequent decision should be oriented toward arriving at the runway in a stabilized, controlled configuration with no requirement for a go-around. This article walks through the aerodynamic realities, step-by-step procedure, key numbers, and the common traps that catch unprepared pilots.
Aerodynamic Realities of One Engine Inoperative
With one engine out, a light twin is a fundamentally different airplane. The operating engine produces full (or near-full) thrust on one side of the fuselage while the inoperative engine produces only drag—particularly if its propeller is windmilling rather than feathered. The asymmetric thrust creates a strong yawing moment toward the dead engine, and the pilot must apply rudder pressure toward the operating engine to maintain directional control.
On a conventional light twin where both propellers rotate clockwise as viewed from the pilot's seat, the left engine is the critical engine. P-factor causes the descending (right) blade of each propeller to produce more thrust; because the right engine's descending blade is farther from the aircraft's center of gravity, it has a longer moment arm and produces the greatest asymmetric yaw. Losing the left engine therefore leaves the right engine—the one with the most powerful yaw-producing moment—as the sole source of thrust, making control demands the greatest. Counter-rotating propellers eliminate this asymmetry and therefore eliminate the critical-engine concept.
The concept of Vmc (minimum control speed, air) is central here. Certified under 14 CFR 23.149, Vmc is the calibrated airspeed at which directional control can be maintained after the critical engine is suddenly made inoperative, with no more than 5° of bank. Vmc addresses directional control only—it is not a climb performance speed. Importantly, Vmc is established at the most unfavorable weight and CG: the lightest weight and the aft CG limit. A lighter airplane actually has a higher Vmc because the lift vector produced by a 5° bank contributes less side force relative to the asymmetric thrust. Never assume the published Vmc reflects maximum gross weight; the airplane is most vulnerable to loss of control at light weights.
Banking approximately 5° into the operating engine lowers Vmc by as much as roughly 3 knots per degree between 0° and 5° of bank. This is one reason zero-sideslip technique—about 2° of bank toward the good engine with coordinated rudder—optimizes OEI climb performance while also keeping Vmc lower than wings-level flight would.
Planning the OEI Approach
Early, deliberate planning is the hallmark of a safe OEI approach. Because climb performance on one engine is severely limited—and may be zero or negative at low altitudes, high weights, or in hot/high conditions—the pilot must treat every OEI approach as a one-shot event. The go-around option is often unavailable, and attempting one at low altitude with full flaps and gear extended can be fatal.
Pilots should accomplish the following before descending below pattern altitude:
- Confirm the engine is failed and feathered (if equipped with a constant-speed, feathering propeller). A feathered prop produces far less drag than a windmilling one and is essential for any realistic single-engine climb or level flight capability.
- Declare an emergency if appropriate. ATC priority handling can provide a straight-in approach and remove traffic conflicts—use it.
- Configure early. Do not wait until short final to extend gear and flaps. Configure at a comfortable altitude so you can assess aircraft response and energy state.
- Brief the go-around decision altitude. Decide in advance at what point a go-around is no longer an option, and commit to landing if you reach that point.
- Aim for a longer runway. If available, use the longest runway with the most favorable wind. Crosswinds are more difficult to manage with asymmetric thrust.
Flying the Approach
The OEI approach should be flown at a slightly higher than normal airspeed. Many manufacturers specify an approach speed in the Pilot's Operating Handbook (POH) for single-engine operations; in the absence of a specific number, pilots commonly add a small margin above Vyse (blue-line speed) on final. Vyse is the best single-engine rate of climb speed; it is marked with a blue radial line on the airspeed indicator and represents the single most important airspeed reference in OEI flight. Flying too slow risks loss of directional control if Vmc is approached, while flying too fast increases landing distance.
Flap extension should be managed carefully. Partial flap settings are often recommended over full flaps for an OEI approach because full flaps dramatically increase drag and worsen go-around performance. Unless the POH specifies otherwise, many instructors recommend extending flaps to an intermediate setting and adding full flaps only when a landing is assured. Gear extension further increases drag, so gear should be extended at a point where a landing is certain and a safe go-around is no longer expected.
Power management on the operating engine is critical. Unlike an all-engine-out glide, the OEI approach uses the good engine to control descent rate and airspeed. The pilot must be prepared for the asymmetric yaw that accompanies power changes and must maintain continuous rudder pressure toward the operating engine throughout. As power is reduced on final, the yaw demand decreases slightly, but foot pressure must be maintained deliberately and not abandoned.
The Landing and Rollout
Touch down on the centerline, ideally at a normal touchdown point, avoiding floating excessively and using excess runway. Because one engine is inoperative, directional control on the rollout uses differential braking and whatever aerodynamic control is available, since rudder effectiveness diminishes quickly at low speeds. Apply brakes symmetrically when possible and be prepared for asymmetric braking if directional control becomes challenging.
After clearing the runway, secure the inoperative engine according to the emergency checklist, shut down appropriately, and notify ATC. Resist the urge to rush the after-landing flow; the emergency is not over until the aircraft is safely stopped and secured.
Why You Cannot Always Go Around
The single most dangerous decision in OEI operations is an unplanned go-around on short final with full flaps and gear extended. At low altitude, dirty configuration, and possibly near or below Vyse, the operating engine may not provide enough thrust to arrest the descent. The drag of full flaps, extended landing gear, and a windmilling (or even feathered) propeller on the dead engine creates a total drag that exceeds the available thrust—particularly in hot, high, or high-weight conditions.
If loss of control occurs below Vmc, the immediate action is to reduce power on the operating engine and lower the nose to regain airspeed. This removes the asymmetric thrust that is causing the loss of control. This is not a last resort—it is the primary and immediate response. Once airspeed is restored above Vmc, power can be reapplied judiciously. This counterintuitive action is essential knowledge for any multi-engine pilot.
Key Numbers and Rules
- Vmc: Maximum 5° bank into operating engine; directional control only; established at lightest weight and aft CG (most unfavorable). Increases as weight decreases.
- Vyse (blue line): Best single-engine rate of climb speed. Use as a reference for OEI approach speeds.
- Vxse: Best single-engine angle of climb speed. Steeper but slower—use only when obstacle clearance is the priority.
- Vsse: Safe single-engine speed. The minimum speed at which intentional OEI training maneuvers are initiated.
- Bank angle into operating engine: Approximately 2° for zero-sideslip (best OEI climb performance); up to 5° to minimize Vmc.
- Flap setting: Intermediate setting recommended during OEI approach unless full landing is assured; full flaps dramatically worsen go-around capability.
- Loss of control below Vmc: Immediately reduce power on the operating engine and lower the nose.
Common Test Traps
- Assuming Vmc is set at max gross weight. It is not. Vmc is established at the most unfavorable (lightest) weight. A heavier airplane actually has a lower effective Vmc due to the greater side force from the banked lift vector.
- Thinking Vmc is a climb performance speed. Vmc addresses directional control only. Confusing Vmc with Vyse on the exam or in the airplane is a classic and dangerous error.
- Identifying the right engine as critical on a conventional twin. The left engine is critical because losing it leaves the right engine—with its greater moment arm—producing the maximum asymmetric yaw.
- Delaying the go-around decision. Committing to a go-around below a pre-briefed decision altitude with full flaps and gear extended may be impossible to execute safely. The exam expects you to know that a go-around is often not an option.
- Forgetting that reducing power is the immediate response to loss of control below Vmc. Students often want to add rudder or bank further; the correct answer is to reduce power on the good engine first and simultaneously lower the nose.