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I am now finishing my PPL (on a C150 in Czech Republic) and today had quite a close call when doing a solo touch-and-go on a short runway. We train on grass (and therefore rarely completely level) runways and take off with flaps 10 (landing with 20 or 30). I stayed in ground effect a couple of seconds before touchdown and then, according to my instructor's (hmm) instructions, first raised the flaps to 10 and then applied full throttle (and carb heat full cold).

I saw trees approaching and cleared them by an uncomfortably small margin (which made my further way back on which I managed to lose track a bit seem like a joke I wouldn't care about).

The explanation I heard from other flying guys is that touch-and-go should be an imitation of landing followed by a take-off, and one should therefore retract flaps (to 10) and then apply full power. And if you are not sure of runway distance left, you should make a full stop and take off anew.

Does this actually hold true? Imitation and practicing is all good and well, but assessing the runway distance left (and more so at an unfamiliar unlevel grass field I was landing at) in one second you might have may prove too risky and may lead to quite different consequences I was lucky to have avoided.

The instructor actually confirmed they were planning to change their route for the long nav flight because this field proved too challenging.

The question is, however, generic: first raise flaps or set full throttle?

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    $\begingroup$ If your wheels were on the ground, pull the flaps up first. If your wheels are not on the ground (go around), power first, then slowly flaps. The issue is that when you retract your flaps in the air you have a tendency to sink, doing it on the ground you can't sink so best to get in the take-off configuration before applying power. Honestly in this situation if you landed too long you should have immediately applied full power in ground effect and started a go-around. If your wheels don't hit at a target point on a short runway, go around. $\endgroup$
    – Ron Beyer
    Commented Aug 24, 2016 at 21:22
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    $\begingroup$ It sounds more like an issue where you should have determined that you didn't have enough runway left for a touch and go, and either committed to a full stop landing or a go around (whichever could be done safely) prior to that point. One good method is to choose a touchdown point while on final, and if it becomes clear that you won't touch down by that point then you should go around. This will keep you out of similar problems in the future. (As to your actual question, you may want to remove all of the extraneous details so that they don't cloud the issue.) $\endgroup$
    – Lnafziger
    Commented Aug 24, 2016 at 21:28
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    $\begingroup$ Thanks for your replies. Passed my checkride and got my license couple of days ago. Examiner put this very same question to me. And upon my answering that I would first retract flaps, said that on a short runway he would recommend to first give throttle. So now I think it's a matter of personal preference, at least in the way of looking at the whole touch-and-go process and objectives. $\endgroup$
    – Andrey Ch
    Commented Sep 2, 2016 at 12:03

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Flaps in a C150 (and pretty much any type) take a few seconds to move. Throttle change is more-or-less instantaneous. If you were to throttle up first, and then change the flap position there is a good chance that you are lifting off while the position of your flaps are changing. This is not a good idea, changing the amount of lift generated by the wings in this crucial stage of flight can lead to a take off stall. You could (and probably will) be too low to recover.

To minimise the chance of this happening, I would say that on touchdown, one of the first things I would do is to set flaps for takeoff ( giving the actuators a second or two to change flap position) before immediately setting take off throttle.

So, yes, your instructor was right. They usually are. In your specific case, I suspect that as soon as you floated too far down the runway, you should have initiated a go-around before touching down. You did not leave yourself enough runway to safely perform a touch-and-go. You dont assess take off distance available once you touch down, you asses it while still flying - you had ~10 seconds to make that call (approach, float, oh shit, go around!)

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    $\begingroup$ Throttle change is near instantaneous, but increase in airspeed (which is what gives the aircraft lift) is not. If you're close to, but not on the ground, it's much safer to go to max power, let the airspeed start climbing, and slowly retract flaps one notch at a time (or slowly, if you don't have notches). Removing flaps reduces drag, but also significantly reduces lift. If you're low, and you go remove flaps without gaining airspeed, you can slam into the ground. $\endgroup$
    – hashinclude
    Commented Feb 23, 2017 at 17:47
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    $\begingroup$ @hashinclude I agree with you entirely - it is a matter of physics after all. This answer assumed you were actually on the ground. $\endgroup$
    – Jamiec ♦
    Commented Feb 24, 2017 at 8:50
  • $\begingroup$ One nit-pick: "Flaps in a C150 (and pretty much any type) take a few seconds to move." Pretty much any type with electric flaps. In planes with Johnson bar flaps (old Cessnas, many Piper models to this day) actuation can be nearly instantaneous as well. $\endgroup$
    – Fred Larson
    Commented Aug 9, 2018 at 16:28

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