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Accelerate-Go vs. Accelerate-Stop: The Takeoff Distances That Matter Most in a Twin

Multi-engine airplanes give you options—right up until they don’t.


If you’ve done enough multi training, you’ve heard some version of:

“An engine failure on takeoff is survivable… if you have the performance and runway to match your decision.”


That’s what accelerate-go and accelerate-stop are really about. They’re not airline-only concepts. They’re the numbers that answer:

  • If an engine quits at the worst possible moment, can I continue and fly away?

  • If an engine quits at the worst possible moment, can I abort and stop?


And the uncomfortable truth in many light twins is this:

  • There are plenty of days where the honest answer is “not really” for one of those options.


So let’s break these down in pilot language, including how they relate to V1-style thinking (even though most GA twins don’t give you a published V1).



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The Takeoff Decision Problem in a Twin

On a single-engine airplane, takeoff planning is mostly:

  • runway length

  • climb gradient / obstacles

  • density altitude

  • weight


In a twin, you add a higher-stakes fork in the road:


If an engine fails on the roll or right after liftoff, you have two choices:

  1. Stop on the runway (reject)

  2. Go (continue takeoff and fly on one engine)


The hard part is that the “best” choice depends on:

  • when the failure happens

  • how much runway is left

  • your weight/DA

  • obstacles

  • your proficiency

  • and the airplane’s real single-engine capability


That’s where accelerate-stop and accelerate-go come in.


Accelerate-Stop Distance: “Can I Abort and Still Stop?”

Accelerate-stop distance is the runway length needed to:

  • accelerate to a decision point (often conceptually near liftoff speed),

  • recognize a failure, and

  • reduce power / brake to a stop on the remaining runway.


Pilot translation:

  • If I reject the takeoff at a high speed, do I have enough runway to stop without leaving pavement?


Why this is tricky in GA twins

Most light twin POHs don’t give you a clean “accelerate-stop” chart like transport-category jets do. You often have to infer it from:

  • takeoff ground roll / distance to 50 feet

  • landing distance data (not a perfect substitute)

  • performance margins and conservative assumptions

  • real-world braking effectiveness (which is rarely “book perfect”)


So for GA pilots, accelerate-stop is often less about a single published number and more about a conservative planning mindset.


Accelerate-Go Distance: “Can I Continue and Clear the Obstacle?”

Accelerate-go distance is the runway length needed to:

  • accelerate,

  • experience an engine failure at a critical moment,

  • continue the takeoff on one engine, and

  • climb to clear a specified obstacle (often 50 feet).


Pilot translation:

  • If I lose an engine at the worst point and continue, can I still get airborne, clean up, and climb away safely?


The reality check: “Go” might mean “go… but descend”

In some light twins at high DA or heavy weight, “go” may mean:

  • you can lift off,

  • you can maintain control,

  • you can fly at Vyse,

  • but you may not climb.


That’s not a failure of the airplane; it’s the physics of limited excess power.


So accelerate-go isn’t just “will it fly?” It’s “will it fly and climb enough to avoid hitting something?”


Where the Decision Point Lives (The GA Version of V1)

Airliners use V1: below V1, stop; above V1, go.


Most GA twins don’t publish a V1, but you still need a decision framework.


A practical GA decision framework

Many multi instructors teach something like:

  • Before liftoff / while there’s plenty of runway: reject for almost any abnormality

  • After liftoff with runway remaining and not stabilized: land straight ahead if possible

  • After liftoff with no runway remaining / committed: maintain control, configure, identify/verify/feather, fly Vyse, and accept whatever performance you get


The key is not the exact wording—it’s having a pre-briefed plan so you’re not inventing a strategy at the worst possible time.


The Speeds That Tie Into This (Vr, Vmc, Vyse)

Accelerate-stop and accelerate-go are tied to the speed regime you’re operating in:

  • Vr: rotation speed—where you transition to flying

  • Vmc: minimum control speed—where directional control can be lost if you’re slow and asymmetric

  • Vyse (blue line): best single-engine rate of climb speed—your best chance at climbing after an engine failure


Here’s the key relationship:

  • If you continue (“go”), you must be able to maintain control (stay above Vmc) and target Vyse once stabilized and cleaned up.

  • If you reject (“stop”), you must have enough runway and braking to stop from a high speed—often with little time to spare.


Why Accelerate-Stop Can Be the Bigger Surprise

Many pilots assume the “stop” option is always safer. It isn’t always.


In a light twin:

  • you’re often heavier than a comparable single

  • you may accelerate quickly

  • brakes can overheat or fade

  • runway contamination (wet/ice) can destroy stopping performance

  • reaction time eats runway faster than you think


A high-speed reject can turn into an overrun in a hurry.

That’s why multi instructors emphasize: brief your reject criteria and don’t delay.


Why Accelerate-Go Can Be the Bigger Lie

If accelerate-stop is a surprise, accelerate-go is the lie pilots tell themselves:


“I have two engines, so I can fly away.”


Sometimes you can. Sometimes you can’t—at least not upward.


Single-engine climb performance can be marginal on:

  • hot days

  • high elevation airports

  • heavy weights

  • airplanes with windmilling props or imperfect cleanup

  • pilots who aren’t sharp on zero sideslip, configuration, and engine secure steps


So accelerate-go planning forces you to ask:

  • What is my expected OEI climb rate today?

  • What is my single-engine service ceiling today?

  • Do I have obstacles that require a minimum climb gradient?


If the answer is ugly, your plan may need to change:

  • reduce weight

  • depart cooler

  • use a longer runway

  • change runway/route

  • don’t go


How to Pre-Brief Like a Professional (But for GA Twins)

Before you taxi, decide:


1) My “reject” triggers

Examples:

  • engine power abnormality

  • directional control issues

  • unsafe airspeed trend

  • warning lights that indicate a real problem

  • anything that makes you doubt you can continue safely


And decide:

  • “I will reject immediately below rotation speed for X, Y, Z.”


2) My “after liftoff” plan

Say it out loud:

  • “If we lose an engine after liftoff, I will maintain control, pitch for a safe speed, gear up, identify/verify, feather, and fly blue line.”


3) My “can I actually climb?” check

Based on today’s conditions, be honest about:

  • whether you can expect a climb on one engine

  • where you’ll go if you can’t

  • what your runway/terrain environment allows


This is the multi-engine version of “don’t take off into a box canyon.”


Bottom Line

Accelerate-stop is “Do I have enough runway to reject at high speed and stop?”Accelerate-go is “Do I have enough runway and performance to continue after an engine failure and clear obstacles?”


In multi-engine airplanes, those two numbers define whether you truly have options when something goes wrong on takeoff.


And the most pilot-useful takeaway is simple:

  • Don’t wait for the failure to decide. Brief the decision before you add power.



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