Engine Failure During Takeoff Before VMC (Simulated) (AMEL, AMES)

For AMEL or AMES the evaluator must select Task E or F; Task G; and at least one other Task. So Task G — the OEI approach and landing — is guaranteed, and you will get either this Task (failure before VMC, which ends in a rejected takeoff) or Task F (failure after liftoff, which ends in a single-engine climb or an off-airport landing).

Prepare both. You do not get to choose which one, and they are two different decisions built on the same speeds.

The engine fails on the takeoff roll below VMC, and the takeoff is rejected. The ACS skills are exactly three (AI.XII.E.S1–S3):

• Close the throttles smoothly and promptly when the simulated failure occurs.
• Maintain directional control and apply brakes (AMEL) or flight controls (AMES) as necessary.
• Analyze and correct common errors.

There is no decision to make and no options to weigh. That is the teaching point — below VMC the airplane has taken the decision away from the pilot, so the only thing being trained is the speed and quality of the reflex.

Because directional control is not available below VMC, whether the airplane is on the ground or airborne:

• On the ground: the takeoff needs to be rejected — directional control can only be maintained by promptly closing both throttles and using rudder and brakes as required.
• Airborne: directional control is not possible with the remaining engine producing takeoff power (AFH 13-15).

That is the reasoning behind the rule you give every multiengine student: the airplane should never be airborne before the airspeed exceeds VMC. Use the manufacturer's VR or VLOF; if no such speed is published, use a minimum of VMC plus 5 knots for VR (AFH 13-15).

VMC itself is the calibrated airspeed at which, following the sudden critical loss of thrust, it is possible to maintain control of the airplane — marked with a red radial line (14 CFR 23.2135(c), AFH 13-2). Note what it does not promise: there is no requirement, under either the current or the historical definition, that the airplane be capable of climbing at this airspeed — VMC addresses directional control only (AFH 13-2).

VYSE is the best rate of climb speed with one engine inoperative, marked with a blue radial line; above the single-engine absolute ceiling it yields the minimum rate of sink (AFH 13-1). It is in this Task's knowledge elements (AI.XII.E.K2) because the two radial lines together are the mental model the student carries into every takeoff.

Give them the pairing: red is control, blue is performance. Below red you have neither. Between red and blue you may have control but no useful climb. At blue you have the best the airplane can offer on one engine — which in a light twin may still be a descent.

Say the framing sentence first, because it is the actual knowledge element: VMC is a fixed airspeed only for the very specific set of circumstances under which it was determined during certification — in reality, VMC varies with a variety of factors, and the VMC seen in practice or in an actual OEI event could be less or even greater than the published value (AFH 13-23). The red radial line is a certification result, not a physical constant — which is why the number you are rejecting the takeoff below is a number you should distrust.

From the historical 14 CFR 23.149 conditions (AFH 13-24):

• Power on the operating engine — VMC increases as power increases. Highest at takeoff power at sea level with normally aspirated engines, decreasing with altitude; with turbochargers it holds constant to the critical altitude.
• Inoperative propeller drag — VMC increases with drag, so it is highest with the propeller windmilling at low pitch, high rpm.
• CG position — VMC increases as CG moves aft; the rudder's moment arm shortens. Aft-most CG is the most unfavorable.
• Weight — VMC increases as weight is reduced.
• Landing gear — VMC increases when the gear is retracted; extended gear aids directional stability.
• Flaps — determined with flaps in the takeoff position (0° for most twins).
• Bank angle — VMC increases as bank angle decreases, by more than 3 knots per degree between 5° and wings-level (AFH 13-25).

Why it matters in this Task specifically: on the takeoff roll most of those factors are set the way that raises VMC — takeoff power on the good engine, a windmilling propeller the instant the other one quits, a lightly loaded training twin, and wings level on the runway, which alone is worth more than 3 knots per degree of the 5° the manufacturer was allowed. Only the extended gear works in your favor. So the airplane's real VMC at the moment of failure sits toward the high end of the range — which is exactly why the answer below rotation speed is "reject," not "evaluate."

The full certification treatment — static versus dynamic determination, the 5° bank allowance, and zero sideslip — is developed in Task XII.F. Send the student there rather than duplicating it here.

Accelerate-stop distance is the runway required to accelerate to a given speed, experience a failure, and stop.

• Regulatory reality: the regulations do not specifically require that runway length be equal to or greater than accelerate-stop distance. Most AFM/POHs publish accelerate-stop distances only as an advisory; it becomes a limitation only when published in the limitations section of the AFM/POH (AFH 13-12).
• What experienced pilots do anyway: insist on runway lengths of at least accelerate-stop distance, as a matter of safety and good operating practice (AFH 13-12).
• Simplest version for a student: add the takeoff distance to 50 feet AGL and the stopping distance from 50 feet AGL. If the runway is no longer than that total, the odds are very good that if anything fails, it will be an off-runway landing at the least (AFH 13-15).
• Instructor's habit to instill: review the takeoff decision as the last item of the before-takeoff checklist (AFH 13-11), spoken aloud — "below blue line on the runway, both throttles closed and we stop."

Promptly close both throttles and maintain directional control with the rudder, nosewheel steering, and brakes. Aggressive use of all three may be required to keep the airplane on the runway, particularly if the engine failure is not immediately recognized and accompanied by prompt closure of both throttles (AFH 13-17).

Priority: maintain control of the airplane as it decelerates, not stop it in the shortest distance — that is the part students get backward. In some situations it may be preferable to continue into the overrun area under control rather than risk directional control loss, landing gear collapse, or tire/brake failure trying to stop short (AFH 13-17).

Both throttles is not a typo — closing only the good one is the actual reflex being trained, because asymmetric thrust with one throttle still up is what puts the airplane in the weeds.

Two hard numbers govern this, and they agree:

• AFH: simulated engine failures during the takeoff ground roll may be accomplished with the mixture control. The simulated failure should be introduced at a speed no greater than 50 percent of VMC. If a learner does not react promptly by retarding both throttles, the instructor can always pull the other mixture (AFH 13-35).
• ACS: engine failure (simulated) during takeoff should be accomplished prior to reaching 50 percent of the calculated VMC (ACS Appendix 2, Multiengine Considerations).

So: half of red line, on the ground, and no faster. Above that you are not training a rejected takeoff, you are conducting one.

Brief it beforehand: surprising a multiengine learner with an emergency without a thorough briefing creates a hazardous condition, and simulated engine failures can very quickly become actual emergencies or lead to loss of the airplane when approached carelessly (AFH 13-35). Say who owns the throttles, who owns the mixtures, and what the abort call is.

• Do not pull circuit breakers. Not recommended for training purposes, and it can lead to a subsequent gear-up landing (AFH 13-35).
• Do not use an abrupt throttle chop where a smooth reduction will do. Smooth throttle reductions avoid abusing the engine and possibly causing damage, and if the engines have dynamic crankshaft counterweights it is essential — severe or repetitive counterweight abuse will eventually lead to engine failure. Check with maintenance or the engine manufacturer whether your airplane's engines are so equipped (AFH 13-35).
• Do not introduce a failure in the air below VSSE. No engine failure should ever be introduced below safe, intentional one-engine-inoperative speed (VSSE); if no VSSE is published, use VYSE (AFH 13-18). That rule belongs to Task F, but say it here so the student never confuses the ground case with the airborne one.
• Do not restore items casually. Whatever you pulled, put back — upon completion of a training session, care should be taken to restore items to their proper positions (AFH 13-35).

• Closing only one throttle. The single most dangerous error, because it leaves the asymmetry in place. Correction: drill "both throttles" as one word, on the ground, in the airplane as a procedures trainer — the engines do not have to be operating for real learning to occur (AFH 13-35).
• Delayed recognition. The yaw is the cue, not the gauges. Correction: teach the student to keep their feet alive on the roll and to expect the reject rather than the takeoff.
• Trying to salvage it. Attempting to fly or to "get it back" below VMC. Correction: rebrief the decision point out loud before every takeoff so there is nothing to decide when it happens.
• Braking before directional control is established — locked wheels, tire failure, or a swerve. Correction: rudder and steering first, brakes as the airplane slows, and remind them control beats distance (AFH 13-17).
• Failure to use full available runway and overrun. Correction: teach that the overrun under control is a better outcome than the gear collapsed on pavement.
• Rotating too early. The root cause of the whole scenario. Correction: hold it on to VR or VLOF, or VMC plus 5 if none is published (AFH 13-15) — and note that with partial flaps many light twins have a strong tendency to become airborne prior to VMC plus 5 knots; the fix is to allow it to become airborne only a few inches above the runway rather than holding it down with forward elevator, which produces wheelbarrowing (AFH 13-17).

Both, and be able to say which and why. The demonstration is short, low-energy, and at half of VMC — it is one of the safest things in the multiengine syllabus, which is exactly why it should be flown rather than discussed. Fly it as the demonstration phase of the demonstration-performance method, with the explanation delivered before the airplane moves (AIH 9-5). Learners generally imitate the instructor's performance, so demonstrate the skill exactly the way they're expected to practice it, including all safety procedures (AIH 9-6).

What stays on the ground is everything above 50 percent of VMC. For the high-speed reject and for scenarios that are hazardous to fly, consider a simulator training center or manufacturer's training course — emergency procedures that would be dangerous or impossible to accomplish in an airplane can be done safely and effectively in a flight training device or simulator, and the device need not duplicate the specific make and model to be useful (AFH 13-36).