14.4 Engine-Inoperative Instrument Flight & Approaches (AMEL/AMES)
Key Takeaways
- ACS Area of Operation VII, Tasks B and C — one engine inoperative in straight-and-level flight and turns, and the instrument approach and landing with an inoperative engine — apply to multiengine airplane checks only (AMEL and AMES), but the underlying knowledge is testable on the IRA written for any candidate.
- The recognition and control flow is fixed: maintain directional control with rudder, then Mixtures, Propellers, and Throttles forward, Flaps up, Gear up, then Identify (dead foot, dead engine), Verify by retarding the suspect throttle, and Feather — with the airplane trimmed to the blue-line best single-engine rate of climb speed, VYSE.
- Zero sideslip, not wings level, produces the best single-engine climb performance: bank approximately 2 to 5 degrees toward the operating engine and hold the inclinometer ball roughly one-half ball width toward the good engine, because wings-level flight with the ball centered costs a large fraction of the remaining climb rate.
- ACS tolerances for engine-inoperative instrument flight are altitude plus or minus 100 feet (or the minimum sink rate if the airplane cannot hold altitude), airspeed plus or minus 10 knots, and heading plus or minus 10 degrees, while the applicant must also assess the airplane's performance capability and choose an action that ensures a safe landing.
- On a single-engine instrument approach the pilot should declare, request the longest and most closely aligned runway with a long final, delay gear extension until landing is assured, use minimum flap, and brief a commitment point — because the published missed approach climb gradient frequently exceeds what the airplane can produce with one engine feathered.
Engine-Inoperative Instrument Flight & Approaches (AMEL/AMES)
Quick Answer: In FAA-S-ACS-8C, Area VII Tasks B and C — engine-inoperative straight-and-level flight and turns, and the instrument approach and landing with an engine inoperative — apply to multiengine airplane checks only. The control flow is maintain directional control with rudder, then Mixtures, Props, Throttles forward; Flaps up; Gear up; Identify; Verify; Feather, trimmed to VYSE (the blue radial line). Best performance comes from zero sideslip, not wings level: bank about 2 to 5 degrees into the operating engine with the ball approximately half a width toward the good engine. ACS tolerances are ±100 feet altitude (or minimum sink), ±10 knots airspeed, and ±10 degrees heading. On the approach, declare early, ask for the longest, best-aligned runway and a long final, delay the gear until landing is assured, use minimum flap, and brief a commitment point — because the published missed approach gradient may be unachievable on one engine.
An engine failure in visual conditions is a performance problem. The same failure in cloud is a performance problem plus a control problem plus a workload problem, arriving simultaneously and requiring the pilot to hold heading and altitude by instrument reference while diagnosing and securing a powerplant. The FAA therefore evaluates it as an Emergency Operations Task, and it deserves a place in every instrument pilot's knowledge even when the checkride will be flown in a single.
1. Recognition in Instrument Conditions
Without a horizon, the initial cues are the ones a pilot feels and reads, not the ones they see outside:
| Cue | What It Looks Like on Instruments |
|---|---|
| Yaw and roll toward the failed engine | Turn coordinator shows an uncommanded rate of turn; heading indicator drifts; the ball departs center |
| Rudder pressure required | Sustained pressure on one rudder pedal to hold heading — the foot that is doing nothing points to the dead engine |
| Loss of performance | Vertical speed indicator sags, airspeed decays, altitude begins to bleed off despite unchanged pitch |
| Engine instruments | Manifold pressure, RPM, fuel flow, EGT, or CHT diverge between the two engines |
[!CAUTION] Engine instruments confirm; they do not diagnose. A windmilling propeller can still indicate near-normal RPM and — at altitude — manifold pressure close to ambient. The flight controls identify the failure; the throttle verification proves it.
2. The Control and Securing Flow
+-----------------------------------------------------------------------------+
| ENGINE FAILURE IN CRUISE OR CLIMB (MULTIENGINE) |
| |
| 0. CONTROL ......... Rudder to stop the yaw. Pitch for VYSE (blue line). |
| 1. MIXTURES ........ FORWARD (as required) |
| 2. PROPELLERS ...... FORWARD |
| 3. THROTTLES ....... FORWARD |
| 4. FLAPS ........... UP |
| 5. GEAR ............ UP |
| 6. IDENTIFY ........ "Dead foot, dead engine" |
| 7. VERIFY .......... Retard the SUSPECT throttle - no change confirms it |
| 8. FEATHER ......... Propeller on the confirmed failed engine |
| 9. SECURE .......... Complete the POH/AFM securing checklist |
| 10. TELL ATC ........ Declare, state intentions, request assistance |
+-----------------------------------------------------------------------------+
The Critical Airspeeds
| Speed | Marking | Meaning |
|---|---|---|
| VMC (VMCA) | Red radial line | Minimum control speed with the critical engine inoperative; below it, full rudder cannot counter asymmetric thrust and the airplane rolls toward the dead engine |
| VYSE | Blue radial line | Best rate of climb, single engine — the speed that buys the most altitude per minute, or the least sink if a climb is impossible |
| VXSE | Not marked | Best angle of climb, single engine; used only when an obstacle must be cleared |
| VSSE | Not marked | Safe, intentional one-engine-inoperative speed — the minimum speed at which an engine should be deliberately cut for training |
Blue line is the number that matters in IMC. Trim to it and hold it. Every knot away from VYSE — fast or slow — costs climb performance, and slow costs control margin as well.
3. Zero Sideslip: Why Wings Level Is the Wrong Answer
After the propeller is feathered, the airplane still has thrust on one side and drag on the other. Three configurations are possible, and only one of them performs:
| Configuration | Ball Position | Result |
|---|---|---|
| Wings level, ball centered | Centered | Requires a large sideslip; the fuselage flies crooked, drag rises sharply, and a substantial share of the remaining single-engine climb rate is lost |
| Wings level, no rudder correction | Deflected toward the good engine | Airplane yaws and turns toward the dead engine; unacceptable |
| Zero sideslip | Approximately half a ball width toward the operating engine, with 2 to 5 degrees of bank into the operating engine | Minimum drag, maximum available climb or minimum sink — the certificated single-engine performance figures assume this configuration |
+-----------------------------------------------------------------------------+
| ZERO SIDESLIP GEOMETRY (LEFT ENGINE OUT) |
| |
| Dead Engine (Left) Operating Engine (Right) |
| [ X ] [ * ] |
| \ / |
| \ Bank 2-5 degrees RIGHT / |
| \ (into the GOOD engine) / |
| \_________________________________/ |
| Ball: about 1/2 width RIGHT |
| |
| Rudder: RIGHT rudder held to stop the yaw toward the dead left engine. |
| Memory aid: "Raise the dead" - the dead engine's wing is raised slightly. |
+-----------------------------------------------------------------------------+
4. Performance Reality and the ACS Tolerances
A light twin at gross weight on a warm day may have a single-engine service ceiling below the MEA. The correct expectation is not "climb to a safe altitude" but "how slowly can I lose altitude, and where will I be when I run out of it?"
- Drift-down: Accept the descent at VYSE and plan the arrival altitude rather than trading airspeed for a climb that is not available.
- Ask ATC for terrain: Request the minimum vectoring altitude (MVA), the nearest suitable airport, and vectors. Under 14 CFR § 91.3(b) the pilot in command may deviate from any rule to the extent required to meet the emergency.
- Fuel management: Cross-feeding, boost pumps, and fuel selector position are POH-specific and are a common cause of a second failure. Follow the checklist rather than memory.
ACS Skill Tolerances (Area VII, Task B)
The applicant must maintain the specified altitude ±100 feet — or the minimum sink rate if altitude cannot be held — airspeed ±10 knots, and heading ±10 degrees, while promptly recognizing the failure, setting the engine controls, reducing drag, identifying and verifying the inoperative engine, simulating feathering, establishing the best engine-inoperative airspeed, trimming, and assessing the airplane's performance capability to ensure a safe landing.
5. The Single-Engine Instrument Approach (Area VII, Task C)
A one-engine-inoperative approach is flown differently from a normal approach in four specific ways.
1. Talk to ATC Early and Ask for Room
Request the longest runway most closely aligned with the wind, a long final (10 NM or more), and no last-minute runway changes. Ask for the approach that requires the fewest configuration changes — an ILS or LPV to a long runway beats a circling non-precision approach every time.
2. Configure Late and Configure Once
- Landing gear: Extending the gear roughly doubles the drag penalty at approach speed. Delay extension until the landing is assured — commonly at glideslope or glidepath intercept on a precision approach, or at the visual descent point on a non-precision approach.
- Flaps: Use the minimum flap setting authorized by the POH for a single-engine landing. Full flaps on one engine may make a go-around aerodynamically impossible.
- Airspeed: Fly the approach at or above VYSE until landing is assured; do not decelerate into the region between VYSE and VMC while still in cloud.
3. Brief a Commitment Point
The published missed approach frequently requires a climb gradient greater than 200 ft/NM, and even the standard gradient may exceed a loaded light twin's single-engine capability. Before the final approach fix, decide and state aloud: "If I am not visual by the decision altitude, I will fly the missed approach and accept the drift-down" — or, if the terrain and performance analysis say otherwise, "past this point I am landing."
4. Do Not Circle
Circling on one engine is strongly discouraged. A circling maneuver adds low-altitude turns, configuration changes, and a possible go-around at the worst moment. If the only available procedure is circling-only, the better decision is usually a straight-in approach at a different airport with better weather.
6. The Single-Engine Airplane Analogue
ASEL and ASES candidates do not fly Tasks B and C, but the same instrument discipline applies to a total power loss in IMC:
- Pitch for best glide immediately and trim — airspeed control is the whole game.
- Squawk 7700, declare an emergency, and ask for the nearest airport with an approach, plus the MVA and a heading.
- Use the navigator's NEAREST page to convert the glide radius into a decision, and load an approach if one is reachable.
- Run the restart flow (fuel selector, boost pump, mixture, magnetos, alternate air/carb heat) from the checklist, not from memory, while the autopilot or a stabilized instrument scan holds the glide.
- Expect the somatogravic and vestibular illusions described earlier in this chapter; fly the attitude indicator, not the seat of the pants.
After feathering the left propeller in a light twin in IMC, which control configuration produces the best available single-engine climb performance?
During an ILS approach with one engine feathered in a light twin, when should the landing gear normally be extended?
Under FAA-S-ACS-8C Area of Operation VII, Task B (One Engine Inoperative during Straight-and-Level Flight and Turns), what are the required altitude, airspeed, and heading tolerances, and to which applicants does the Task apply?
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