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TLDR; See Update #2 and #3. The FAA on the one hand says "It has not been established that this procedure results in a shorter takeoff run... " but then requires the same procedure as part of the check-ride. Interesting!


The standard training for a light single-engine short-field takeoff is to run the engine to full throttle before releasing the brakes. Why? This seems hard on the engine, and the 3-5m of ground roll it potentially saves is utterly irrelevant for any kind of sane flying.

Is it just that when doing a short-field takeoff, the regulators would like us to know, and employ, every arrow in the quiver of maximizing takeoff performance?

Or, put another way, once I take all other factors into account, and leave myself a sane factor of safety (which is going to be several hundred meters, not 5 or 10), is there a subtle reason why running up the engine and checking the instruments before releasing the brakes is any different from checking the instruments during my ground roll? In both cases my life is on the line and I am extremely self-interested in doing a complete and thorough job.

And, put one last way, why shouldn't we just do short-field takeoff procedures on every takeoff? If there's no harm to the plane, what do we stand to lose?


I believe the best answer is https://aviation.stackexchange.com/a/94370/20394. Ushby eloquently argues that the problem is not having 15' extra room taking off, it's having 15' extra stopping room in the event of an aborted take-off.

Note, however, there is still room for an explanation of why standard procedure for all takeoffs is not to run the engine to full-power before releasing the brakes.

Update #2

https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/airplane_handbook/07_afh_ch6.pdf

The pilot should apply takeoff power smoothly and continuously, without hesitation, to accelerate the airplane as rapidly as possible. Some pilots prefer to hold the brakes until the maximum obtainable engine revolutions per minute (rpm) are achieved before allowing the airplane to begin its takeoff run. However, it has not been established that this procedure results in a shorter takeoff run in all light, single-engine airplanes.

Update #3

We learned from 757Toga that the aviator's handbook and the check-ride requirements are inconsistent:

Doing some additional research, it seems that the Private and Commercial ACS (PVT ACS https://www.faa.gov/training_testing/testing/acs/media/private_airplane_acs_change_1.pdf) require full power, then release the brakes as part of the checkride requirements to demonstrate a Short-Field Takeoff for a Commercial or Private Certificate. In the Private ACS it's Skills PA.IV.E.S7/8. (page 25 in the PVT ACS.)

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Jamiec
    Aug 11, 2022 at 8:23
  • $\begingroup$ My instructor also taught me that the full-power run is when you lean for best power at high density altitude. $\endgroup$
    – Jeff B
    Aug 12, 2022 at 18:58

5 Answers 5

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In a short field takeoff things happen fast, the window for an abort is small, so the main reason for running the engine to full power is to make sure full power is available before you start to roll. It takes a few seconds to develop full power, and you don't want to be a quarter of the way down the runway before you find out it's running rough or isn't at full RPM - by the time you realize there's a problem you may be past the point where you can safely abort your roll.

Going to full power before you start your roll lets you give the engine instruments your full attention, you don't just push it all the way forward and then release the brakes, you should check your RPM and then run through the critical instruments: temperature, pressure, charge and suction. Once happy with those you then release your brakes and concentrate on flying without distractions.

Also, it may be only 30 feet or so, but 30 feet can make a difference in a short field takeoff. Anything you can do to get that little bit more is worth it.

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Jamiec
    Aug 11, 2022 at 8:23
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Two reasons come to mind. First, you want maximum acceleration to minimized distance to reach takeoff speed and this provides that from the very start. Second, the increased airflow from the propeller provides increased authority to the elevator, allowing more pitch-up if doing this on a soft field (where short field performance often happens), thereby unloading the landing gear and its surface drag. If flaps are down on a high wing aircraft, some of the prop wash may strike them, providing lift even at zero ground speed.

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    $\begingroup$ @DeepSpace While technically correct you ignore his point that additional lift can be created without ground roll, on which a short field takeoff does depend. $\endgroup$
    – Pilothead
    Aug 8, 2022 at 9:46
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    $\begingroup$ @Christian Is it? You can have a ground speed of 0 and an airspeed of 100 knots in a very strong head wind. You can even have a negative ground speed and a positive airspeed if your brakes are not very strong :) $\endgroup$
    – DeepSpace
    Aug 8, 2022 at 12:40
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    $\begingroup$ @DeepSpace, “Lift is never dependent on ground speed.” That’s Jim’s point… $\endgroup$ Aug 8, 2022 at 14:21
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    $\begingroup$ @Joshua The amount of lift depends on the amount and deflection of the propwash, so more is better. The Ryan 92 VZ-3 could lift itself off the ground with two huge props and giant flaps, so not even close to negligible. The NASA X57 uses eighteen electric motors spread across the wing leading edge to effectively double lift, also not negligible. A stock c150 is probably closer to negligible, though still non-zero. $\endgroup$
    – Pilothead
    Aug 8, 2022 at 20:40
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    $\begingroup$ @Christian because we don't have huge fans that can generate ~170 knots headwind at will deployed at every airport. $\endgroup$
    – DeepSpace
    Aug 9, 2022 at 9:49
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As a general rule you are correct that the AFH does not require a pilot to run up to maximum power while holding the brakes, prior to starting the takeoff roll. That being said, many airplane POHs (eg C172) describe this as the preferred technique in the Normal Procedures section. Where an AFM lists this technique, it will also be the takeoff technique used for charting the ground roll and obstacle clearance distances in the Performance section of the POH. Deviating from this, or any other technique published in the POH, does not guarantee you that your aircraft performance will matched the published data. And on a real short field takeoff, a few extra feet might make the difference between success and tragedy.

The real advantage in holding the brakes and running full power prior to beginning to take off role is, when the brakes are released, it guarantees you the aircraft engine is operating at full available power throughout the entirety of the takeoff roll. Engines often takes several seconds to reach maximum power, and that can eat up valuable runway.

For light airplanes, a brief run up to maximum power prior to beginning to take off role while holding the brakes will not harm the aircraft. Excessively running the engine at maximum power with minimal air speed could potentially pose an overheating problem, but it would take several minutes of doing this continuously to begin to pose such a risk.

In short, the AFH is correct as a general technique, but the pilot should always operate the aircraft using the short field technique specified in their airplanes flight manual.

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  • $\begingroup$ That's a solid point about the POH, the one for the 7ECA says the same. Although if the FAA states that there is no proven difference for light singles-- which the 7ECA and C172 definitely are-- then I have to wonder where the manufacturers' recommendations came from. Do they know something the FAA doesn't? Or were they were meeting the FAA's past expectations, which have now updated? $\endgroup$ Aug 10, 2022 at 21:34
  • $\begingroup$ In truth, I’m not sure why the FAA even makes that comment in the airplane flying handbook, as I have never heard of a manufacturer of a light single engine airplane using another technique for short field takeoff. Larger, more powerful, conventional landing gear aircraft such as a P-51 cannot follow that technique as the tailplane cannot maintain pitch authority with the brakes held above 40” MAP. But every light, tricycle gear airplane over heard of - Cessnas, Cirruses, Diamonds, Mooney, etc. - holds brakes w/ a full power run up. $\endgroup$ Aug 10, 2022 at 22:44
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You seem to underestimate 3-5 meters and a few seconds, when you should not do that.

First of all, never assess this circumstance with the Take Off Distance and neither let it play a part in your judgment, that's because TODA (Take off distance available) calculates also for the clearway, which is not a place or time that you happen to be on ground, but rather a height you reach above the ground. Take off distance is calculated including that.

Full power is being set using brakes for many reasons, that come from challenging TORA, TORR and EDR, (Take Off Run Available, Take Off Run Required and Emergency Distance Required, respectively).

You might have what seems to you as enough ground roll but the StopWay occupies a big portion of that (Stopway + TORA = EMDA/ASDA), therefore it's best to save as much. Especially when most short-field takeoffs are very critical in calculation and you're always marginalized by plenty factors and distances(not one distance), a pilot's best choice is to reduce as much as they can to substitute better than to keep guessing.

Other reasons one would assume is the fact that you might not initiate takeoff roll checklist before lining up, engines and max RPM and Break Energy required aren't guaranteed so it's better to add that procedure. You wouldn't worry as much if you had 3000ft runway.

Attention span, getting done with T's and P's reading, and multiple engine sounds and indicators will give you enough time to assess the critical situation you are in, which is probably a mountain somewhere on a wet threshold and humid weather.

I am sure there are other reasons.

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  • $\begingroup$ "You seem to underestimate 3-5 meters" Assuming that my airplane accelerates at 1/4g at full throttle, then 2 seconds of full throttle acceleration is $1/2 * a * t^2 = 5m$ of ground roll. Even assuming 1/2g of acceleration we only get 10m. So I am confident that my numbers are representative of the airplanes I have flown (SEL, <250hp). $\endgroup$ Aug 9, 2022 at 21:30
  • $\begingroup$ "EMR occupies a big portion of that" this is a really good point, and one I think all the others have missed. The distance to clear the obstacle isn't a big deal-- you should be missing it by hundreds of meters, not 5 or 10--, but the stopping distance remaining after an aborted takeoff might well be critical. There are many cases where 5-10m of extra braking distance was the difference between a runway excursion and a safe stop. $\endgroup$ Aug 9, 2022 at 21:33
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    $\begingroup$ I have corrected the abbreviations above, EMR is actually the total Distance (TORA + StopWay), It's actually called the Stopway. Check this: youtube.com/watch?v=XiVM0w9YquQ Do you still think 10 is not good ? I assume you're flying the SE on an international runway where you don't even see the end of it. $\endgroup$
    – user64784
    Aug 9, 2022 at 21:47
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    $\begingroup$ Very impressive takeoff, thanks for the video. I imagine that pilot has a lot more in mind for that operation than just running the engine to full-power before departure. Also, as a turbine it will take significantly longer than 2 seconds to reach full power (contrary to any standard GA trainer). P.S. I note that the pilot's point of departure was 10m from the runway threshold, so even here in a hardcore short-field takeoff the pilot isn't using all available runway. $\endgroup$ Aug 9, 2022 at 22:04
  • $\begingroup$ @KennSebesta: They probably knew they had a comfortable margin with that headwind in that plane (probably a takeoff they'd made many times before), and without spotters outside the plane didn't risk backing up all the way to the cliff edge behind them, at the end of the runway they started from. Note how they take off before the end of the runway and climb away easily, not just barely level flight off the end of the runway (out over the cliff for 60 ft of free altitude.) Although that was without an engine failure, and that's where they'd be pushing the limits of available runway. $\endgroup$ Aug 11, 2022 at 7:15
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It has no effect on the engine whatsoever.

Aero engines are highly decoupled from the drivetrain via a very hefty fluid coupling.

Now in engine design, insulating an engine from drivetrain vibration (think: tracked vehicle) is very effectively dealt with by a fluid coupling. And aviation uses a compressible fluid -- the air.

The engine/propellor has no earthly idea that you're holding the brakes and that the plane is not moving. Its frame of reality is only airspeed, which is subject to winds and varies, obviously.

Thus, the matter of "holding brakes" is entirely a human perception, and it is not a reality that affects the engine. Holding the brakes in a 10kt headwind is no different than rolling 7kt in a 3kt headwind.

While the vibration may be highest at lowest speeds, keep in mind that aircraft engines and mounts must be designed or much worse than that - they must be designed to endure a broken prop. While it's true aluminum has no fatigue limit... an aircraft which was degraded by run-up vibration would be unworthy of a certificate.

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  • $\begingroup$ aircraft engines are not "highly decoupled from the drive train" - quite the opposite $\endgroup$
    – warren
    Aug 25, 2022 at 12:40
  • $\begingroup$ @warren Think more broadly. they are highly decoupled by nature, since they are pushing on air. The air is compressible and provides far superior decoupling to a liquid torque converter. $\endgroup$ Aug 25, 2022 at 20:35

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