Soft-Field Landing and the Flight Test Guide

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youhavecontrol
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Soft-Field Landing and the Flight Test Guide

#1 Post by youhavecontrol » Tue Aug 22, 2017 9:42 am

I have been mulling-over this in my head for a while now and I'm wondering what everyone's opinion is on this statement in the PPL flight test guide regarding the soft field landing technique:

"keep the nose wheel off the ground as long as possible with appropriate use of power and elevator
control, while decelerating in consideration of the remaining length of available runway"

In my experience, there's very few fields where holding the nose OFF the ground after touch-down for any extended amount of time has any practical purpose, because most soft fields are also short... and most people aren't landing in a bog. Yes, you hold the aircraft weight OFF the nose with back-pressure, but keeping extra power/speed just for the purpose of keeping the nose up seems like a useless maneuver. Every time I've landed on grass, I've lowered the nose slowly and GENTLY while the elevators were still effective, then added back-pressure again to relieve the weight on it as I apply the brakes (increasing back-pressure as brakes applied).

Any time I've seen the nose held up for too long on the roll-out, it often drops down with more force as the airspeed decreases. The elevators lose their effectiveness and the nose comes down faster from higher, than if you simply lowered it yourself gradually (especially in Diamond aircraft).

Even watching videos on YouTube of actual Grass Landings (not soft-field technique videos), I couldn't find any where they kept the nose up for more than 5 seconds. In fact, most lower it right away and then brake using back-pressure.

The flight test guide says what it does, so we teach it that way, but is it practical? Realistic?
Any thoughts?
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Re: Soft-Field Landing and the Flight Test Guide

#2 Post by lownslow » Tue Aug 22, 2017 9:56 am

youhavecontrol wrote:"keep the nose wheel off the ground as long as possible with appropriate use of power and elevator
control, while decelerating in consideration of the remaining length of available runway"
Translation: don't dig the nosewheel in but don't keep so much power on in its prevention that you roll off the end.

Or let go of the stick on touch down and klomp on the brakes. Whichever.
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Re: Soft-Field Landing and the Flight Test Guide

#3 Post by youhavecontrol » Tue Aug 22, 2017 10:20 am

But what I want to know is, do they expect the pilot to taxi faster just so the nose can remain off the ground after landing? Even if you landed in the first 1/3 of a 3000' runway, do you have to taxi the remaining 2000' fast and with enough power to to keep the nose off the ground, just until the end when you exit? How long is "as long as possible"?

The way they wrote it, it reads to me literally, that they expect the nose to be off the entire time with power applied to keep it that way for as long as your taxi roll-out.

I'm gonna do some more digging and ask the local examiners about their opinion of it.
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Re: Soft-Field Landing and the Flight Test Guide

#4 Post by lownslow » Tue Aug 22, 2017 11:04 am

Look at it this way: as you decelerate you'll be holding the nosewheel a little off the runway by pulling in progressively more and more up elevator. Eventually that elevator is going to hit the stop and as the plane slows further the nose will gently lower to the ground. That's 'as long as possible.'
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Re: Soft-Field Landing and the Flight Test Guide

#5 Post by trey kule » Tue Aug 22, 2017 11:13 am

because most soft fields are also short...
Really? This is a common flight training misconception that invariably gets students confused trying to do both a soft and a short field takeoff or landing.
Because the landing surface is not paved does not make it a soft field...but a gravel strip might need special techniques to protect the prop..
As to your question, I think you are reading far more into the flight test guide than is necessary, and as a result, looking at extremes like taxiing with the nose wheel off the ground..

K.I.S.S.
In a soft field try to gently touch down the mains on a tricycle gear. Not let the nose wheel thump onto the ground, but gently lower and keep light as far as practical depending on the strip length. Keep moving,,,,keep moving. But if you sink and do stop....do not...I cant overemphasize this, try to power out of the problem.. Time to shut down and get out and look at things.

Btw. Some planes were really never designed go be flown into or out of soft fields...as a pilot you should be able to figure which ones arent.. .

The King videos have a very nice example of a real soft field t/o. And landing..
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Re: Soft-Field Landing and the Flight Test Guide

#6 Post by CpnCrunch » Tue Aug 22, 2017 11:25 am

Typically you only use power to cushion the landing. As soon as the main wheels touch, you cut the throttle. I think the flight test guide is talking about using power in the flare, NOT when the wheels are actually on the ground.

Most soft fields that I've come across are not short. There are some short grass fields, but generally they aren't very soft. Obviously you'd modify your technique in this case and not use power to cushion the landing (assuming that the main wheels won't dig in).

If it's a short field AND you're worried about the main wheels digging in, you probably shouldn't be landing there.
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Re: Soft-Field Landing and the Flight Test Guide

#7 Post by youhavecontrol » Tue Aug 22, 2017 11:54 am

Trouble is, I've even watched videos from Canadian flight schools emphasizing the use of power after touch-down and holding the nose high for the remaining runway length. I agree that it's not necessary and this stuff should be kept simple, but the test guide states it pretty clear (from what I read) that they want power, as necessary to keep the nose up AFTER landing:
g: touch down in the first one third (1/3) of the runway/landing surface;

h: touch down using power as necessary to achieve and maintain the landing attitude for the slowest possible touch down on the main wheels while preventing nose wheel or tail cone contact with the ground;

i: keep the nose wheel off the ground as long as possible with appropriate use of power and elevator control, while decelerating in consideration of the remaining length of available runway;
This isn't always possible, or safe, for that matter, if your primary training aircraft is pathetic at soft-field operations in general... such as the Diamond Eclipse. With the T-tail, that thing has very little prop-wash over it's elevator and the elevator surface area is tiny compared to Cessna or Piper, so you need a lot more speed to keep the elevator effective. This means, that if a person tried to keep the nose up for too long in the roll-out, they would have to taxi stupid fast or watch the nose drop with a 'thud' as the speed drops below the effective range of the elevator.

I just with they'd change the wording in the test guide. It seems different schools have different interpretations of it even... and I certainly have NEVER seen a bush aircraft land on any runway, just add power and keep the nose high for the heck of it, unless the ground was crazy rough.
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Re: Soft-Field Landing and the Flight Test Guide

#8 Post by CpnCrunch » Tue Aug 22, 2017 12:13 pm

Can you post a video of that?
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Re: Soft-Field Landing and the Flight Test Guide

#9 Post by photofly » Tue Aug 22, 2017 1:56 pm

CpnCrunch wrote:Typically you only use power to cushion the landing. As soon as the main wheels touch, you cut the throttle. I think the flight test guide is talking about using power in the flare, NOT when the wheels are actually on the ground.
Respectfully, I disagree with that. Add a touch of power just *as* the main wheels touch. Once you've got the airplane stable on two wheels, gradually idle the throttle, and lower the nose. The idea is not to roll the whole runway length with the nose gear in the air; instead to demonstrate that you have the finesse to land on and remain on two wheels and to lower the nose wheel gently when you and only you decide. A count of two is quite sufficient to prove the point.
Most soft fields that I've come across are not short. There are some short grass fields, but generally they aren't very soft. Obviously you'd modify your technique in this case and not use power to cushion the landing (assuming that the main wheels won't dig in).

If it's a short field AND you're worried about the main wheels digging in, you probably shouldn't be landing there.
I do agree with this.

If your flight test aircraft isn't ideal for demonstrating the technique, that's something you can discuss with the examiner.
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Re: Soft-Field Landing and the Flight Test Guide

#10 Post by youhavecontrol » Tue Aug 22, 2017 2:18 pm

CpnCrunch wrote:Can you post a video of that?
Now I feel like I'm eating my words after what I posted last :oops: . Last time I watched the video was more than a year ago, but it made me raise my eyebrows at the time. I just re-watched the video from the flight school and they don't taxi the full length, but they kept the power in during the roll for about half the runway before closing the throttle and setting the nose down. Even saying on the landing roll after touch-down, "the power is now at 1400rpm." and rolling for about 10 more seconds before lowering the nose. ..so not as long as I remembered.. but it was still long enough for me to look at the demo and think, "nose up that long? do I teach this right?" and then reading the flight test guide and going "woa.."

I don't want to post the video, because I don't feel right about posting another person's content for criticism. ..especially a CFI demo video from a guy with probably more hours than me.
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Re: Soft-Field Landing and the Flight Test Guide

#11 Post by CpnCrunch » Tue Aug 22, 2017 3:07 pm

Yeah, that's definitely weird. Perhaps they were just demonstrating keeping the nose in the air for a long time?

If you cut the power when the main wheels touch, there's no problem keeping the nosewheel in the air for a while. I'm not sure why you'd need to have any power after the main wheels are on the ground. Generally the touch of power is just before touchdown, to cushion the landing. If you only add power after touchdown, I don't see what is being achieved. (Unless I'm misunderstanding photofly).
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Re: Soft-Field Landing and the Flight Test Guide

#12 Post by photofly » Tue Aug 22, 2017 3:23 pm

Well, I don't need power to cushion the landing, and in fact if you read the flight test guide carefully a soft landing isn't one of the criteria the candidate is judged on. You're (merely) looking for a slow landing on the main gear, keeping the nosewheel up in the air and under control. That is, it's a landing on a soft field that you're trying to achieve, not a soft landing on a field.

I use the power to counteract the nose down moment created by the drag from the grass (or whatever). That means applying the power as the wheels start to drag, at the point of touchdown.

Here's the relevant part:
touch down using power as necessary to achieve and maintain the landing attitude for the slowest possible touch down on the main wheels;
keep the nose wheel off the ground as long as possible with appropriate use of power and elevator control, while decelerating in consideration of the remaining length of available runway;
So that's what I do.

To be honest, when demonstrating on clean tarmac you don't even need to add any power, and as the flight test guide makes clear ("as necessary") you're not obliged to.
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Re: Soft-Field Landing and the Flight Test Guide

#13 Post by youhavecontrol » Tue Aug 22, 2017 3:42 pm

Now I'm really itching to talk with the examiners I know about this to see what they look for/expect. Anyone on here a TC examiner?

I emphasize power as required when I teach the touch-down, because I've had students flare perfectly, having the aircraft settle down nice and slow, only to rise up again as soon as they add the power they think is mandatory in soft-field (happens mainly in the Diamond because it's practically a glider). I can see using power for a brief moment, as the mains touch, in especially soft conditions to counteract drag, but certainly not for very long.
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Re: Soft-Field Landing and the Flight Test Guide

#14 Post by trey kule » Tue Aug 22, 2017 3:49 pm

Yeah, that's definitely weird. Perhaps they were just demonstrating keeping the nose in the air for a long time?
Taxiing with the nose gear off the ground seems to be one of those " hey watch me" things, so I expect you might be right. Lots of 206s with bent tail cones from idiot show offs.

To the OP, I still think you simply are not interpreting the guide properly.
When I read it, it seems to me it is saying gently lower the nose gear at the slowest posdible speed, keeping in mind that the runway remaining needs to be considered.....so you are not adding power and oh so gently and lightening the nose gear....and overrunning the runway.

Common sense.
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Re: Soft-Field Landing and the Flight Test Guide

#15 Post by youhavecontrol » Tue Aug 22, 2017 4:00 pm

trey kule wrote: To the OP, I still think you simply are not interpreting the guide properly.
Photo pretty much explained it so no need for me to repeat.
I get the photo pretty clear, but the flight test guide isn't based on if the student flips the plane over or not. I'm still curious about how to define "keep the nose wheel off the ground as long as possible." Why do they specify it in that way? As long as possible is a crazy long time when you have power available. I don't think they're careless in their words, so as literal as TC can be, this literally doesn't make sense to me. I guess what I'm asking is what does TC expect after writing like this, and what's the overall consensus on how they wrote it? I don't want to see a student lose marks because the examiner didn't see him roll for 2000' on a paved runway with the nose up.
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Re: Soft-Field Landing and the Flight Test Guide

#16 Post by photofly » Tue Aug 22, 2017 4:17 pm

trey kule wrote:
Yeah, that's definitely weird. Perhaps they were just demonstrating keeping the nose in the air for a long time?
Taxiing with the nose gear off the ground seems to be one of those " hey watch me" things, so I expect you might be right.
That's the perfect way to practice the technique; but the idea is to be able to do it on grass, not on tarmac. And for a count of two, not for 2000' of runway.
Lots of 206s with bent tail cones
.
Well, don't do that. Obviously.
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Re: Soft-Field Landing and the Flight Test Guide

#17 Post by photofly » Tue Aug 22, 2017 4:18 pm

double post
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Re: Soft-Field Landing and the Flight Test Guide

#18 Post by CpnCrunch » Tue Aug 22, 2017 4:26 pm

photofly wrote:Well, I don't need power to cushion the landing, and in fact if you read the flight test guide carefully a soft landing isn't one of the criteria the candidate is judged on. You're (merely) looking for a slow landing on the main gear, keeping the nosewheel up in the air and under control. That is, it's a landing on a soft field that you're trying to achieve, not a soft landing on a field.
I think the point is that if you land on a soft field you should make a soft landing so the main wheels don't dig in. I learned to fly on grass and was taught to use power to cushion the landing, and all the flight schools I've been to all seem to teach that technique for soft field landings. (The one with the SOPs specifically says to add power in the flare).
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Re: Soft-Field Landing and the Flight Test Guide

#19 Post by CpnCrunch » Tue Aug 22, 2017 5:24 pm

I see the flight test guide does mention about using power after landing. I've never noticed a forward moment from grass. The only place I can see this being advocated is whittsflying.com saying "Use power to keep the aircraft rolling nose-high until ground conditions allow the nose wheel to be lowered". Presumably this is if you land in water or mud, and need to keep the nose-wheel off the ground until you're over more firm ground. I think this would be a pretty unusual occurrence for landing in something with a nosewheel.
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Re: Soft-Field Landing and the Flight Test Guide

#20 Post by pelmet » Tue Aug 22, 2017 5:38 pm

After touch down at idle power, hold up elevator as the aircraft slows down during the landing roll in order to keep the nose wheel off the ground as long as possible. As you slow down, more and more aft elevator is required to keep the nosewheel off the ground until such time as you have full aft elevator. Keep holding this full aft elevator as the aircraft continues to slow down and throughout the taxi in order to lighten the load on the nosegear

Works well on some aircraft like Cessna's and not so good on Piper's where I found the nose came down pretty much right away regardless. In other words, the effectiveness of this varies from aircraft type to aircraft type.

It is possible in certain circumstances that a pilot might keep some power on for a particular reason but that is an additional technique to the above.
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Re: Soft-Field Landing and the Flight Test Guide

#21 Post by PilotDAR » Tue Aug 22, 2017 6:27 pm

As it was a wet spring and early summer, my runway remained soft, so all my operations were soft field, just to reduce rutting the runway. For me that's a power on approach with full flaps, Touch in an area I know to be more firm, flaps back to 15 for most elevator effect during rollout, while holding nosewheel just off. Power as needed to carry the plane to the point where I know it will roll to a stop for turnoff nicely. Nosewheel just off will settle on as speed decays/power reduced - no dropping the nosewheel on - gentle!

Back track for takeoff is 15 flap, stick all the way back, power, nosewheel just off the surface, until I stop to turn around. Takeoff 10 flap, nose very high to transfer the weight to the wings as early as possible. break ground with stall warning, then hold in ground effect to accelerate to a safe climb away speed.
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Re: Soft-Field Landing and the Flight Test Guide

#22 Post by crazyaviator » Tue Aug 22, 2017 6:30 pm

IF you know you are going into a soft and short field' LOAD the aircraft to its aft C of G limit . ( ballast if necessary ) That way, you can land slowly , touch down on the mains and KEEP the nosewheel off the grass until it is PARKED using power as required ( If you are good enough ) Ask me how I know ! BTW, It is always good practice to load the plane towards its aft C of G anyways !
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Re: Soft-Field Landing and the Flight Test Guide

#23 Post by photofly » Tue Aug 22, 2017 7:36 pm

CpnCrunch wrote: I think the point is that if you land on a soft field you should make a soft landing so the main wheels don't dig in. I learned to fly on grass and was taught to use power to cushion the landing, and all the flight schools I've been to all seem to teach that technique for soft field landings. (The one with the SOPs specifically says to add power in the flare).
We disagree then: I dont think that's the point. Of course you shouldn't dig the main gear in, but you shouldn't knock the wings off or jarr your passengers spines either. Even on a soft surface, achieving a soft enough touchdown not to dig the gear in requires only normal technique. (Unless your normal landings are truly dreadful). Whereas keeping the nosewheel up in the manner TC wants you to does require special technique. According to TC.

It's funny how different our experiences are, too. I have never been taught or needed to add power to cushion a landing, on any surface, except to fix screwing up by flaring too high. Nor have I been to a flight school that advocated it. Doing so would also contradict the flight test guide, the Flight Training Manual and the POH for the 172 and 150. Make of that what you will, and maybe the aircraft the OP is flying has different procedures, but...

I've always found the best way to get a soft touchdown is to worry about everything else instead - airspeed, attitude, flaring at the right place and holding the nose up etc. There's even a rude phrase for doing it wrong: "fishing for a greaser".

Regardless, specifically a soft touchdown isn't part of the criteria for the soft-field approach and landing exercise. I don't think that's an error or inadvertent omission on the part of Transport Canada.
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Re: Soft-Field Landing and the Flight Test Guide

#24 Post by photofly » Tue Aug 22, 2017 7:48 pm

CpnCrunch wrote:I see the flight test guide does mention about using power after landing. I've never noticed a forward moment from grass. The only place I can see this being advocated is whittsflying.com saying "Use power to keep the aircraft rolling nose-high until ground conditions allow the nose wheel to be lowered". Presumably this is if you land in water or mud, and need to keep the nose-wheel off the ground until you're over more firm ground. I think this would be a pretty unusual occurrence for landing in something with a nosewheel.
Once again we disagree :) - that sounds exactly what the flight test guide is asking for, and exactly how it should be done!
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Re: Soft-Field Landing and the Flight Test Guide

#25 Post by CpnCrunch » Tue Aug 22, 2017 7:58 pm

photofly wrote: add power to cushion a landing...Doing so would also contradict the flight test guide, the Flight Training Manual and the POH for the 172 and 150.
I'm not sure how it would contradict any of those. The FTG specifically says to "touch down using power as necessary".
photofly wrote: I've always found the best way to get a soft touchdown is to worry about everything else instead - airspeed, attitude, flaring at the right place and holding the nose up etc. There's even a rude phrase for doing it: "fishing for a greaser".
I'd agree with that. But it's just much easier to consistently get a greaser by using some power, which is why most flight schools (except perhaps yours) advocate it. I have to ask: how much actual experience of real soft-field landings do your instructors and students actually get, given you have a tarmac runway there?
photofly wrote: Regardless, specifically a soft touchdown isn't part of the criteria for the soft-field approach and landing exercise. I don't think that's an error or inadvertent omission on the part of Transport Canada.
Perhaps it should be. Anyway, I'm more interested in having a good technique for actual soft-field landings on beaches and grass strips rather than just trying to do the minimum necessary to pass the flight test.
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