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The most reliable way to do a forced landing? High Key / Low Key

Pilot_DAR wrote:

It’s excellent to be aware of your own limitations. When I’m training a pilot, if they cannot cross the threshold within 20 feet of height, and 5 knots of speed, without fiddling the power to do it, we keep practicing until they can. Period. I don’t sign off the type training until the pilot has mastered that amount of precision.

That seems like a heroic amount of precision to me, for a private pilot. Are there no gusts in Canada? I was taught that “fiddling with the power” as you called it is the one way to control your altitude on approach.
Ah wait, I forgot were talking about PFLs here…

Well in that case I still think the precision of “within 20ft” is still ridiculously ambitious.

Last Edited by MedEwok at 14 Feb 08:42
Novice pilot
EDVM Hildesheim

…as some millenary cultures might say ‘perfection is the enemy of the good’ :)

Enstone (EGTN), Oxford (EGTK)

Pilot_DAR wrote:

I don’t understand “unloading the wings” associated with a flare. Unloading the wings to me means pushing to achieve less than 1G, which is exactly the opposite to flaring for landing. When flaring, you’re trying to load the wings to create the additional lift required to arrest the rate of descent.

For simplicity, let say you are at 300ft height above the runway threshold at 100kts with not much remaining runway
Target speed & hight was to be at 50ft hright and 75kts speed but it is not it is not your day

You have the following choices:
A) Slow down to 60kt (load wings), accelerate back to 75kts (unload wings) and flare
B) Do nothing and keep flying at 100kts, slow down to 75kts and flare
C) Try something fancy (steep turn, change field, orbit, S-turns)
D) Accelerate to 130kts, then slow down to 75kts and flare
E) It is impossible to be in that situation

If know how to plot a drag/polar curve vs speed you will get my point (more drag = less energy)
It really does not matter how much runway you have

Few things,
- Power-off/nose down you will not kill yourslef raising flaps at 60kts while pushing stick forward (talking about SEPs not 747s or DC3s)
- A is the closest you can get to parachute without BRS/CAPS, at 300ft is of no good but I would go for CAPS as my best option
- You can raise flaps anytime speed is higher than VS1, not to be confused with raising flaps on power-on/nose up go-around

RobertL18C wrote:

…as some millenary cultures might say ‘perfection is the enemy of the good’ :)

I don’t think (50ft height, +5kts speed) is a good assumption for real forced landings (outside practice) unless that is what you do for a living
I have done 6 field landings (4 in Gliders, 1 in TMG and 1 in SEP), nowhere near those tolerances but enough ground roll
Practicing in 10kts winds in 2-seats is one thing, forced landing in 30kts winds in a 4-seats will never go to plan but into wind will save the show

Last Edited by Ibra at 14 Feb 12:25
ESSEX, United Kingdom

Surely if you are at 300ft above the runway threshold at 100kt then you have no chance whatever of landing, unless the runway is 3km, or you have a massive headwind

If that happens then you are surely buggered because 300ft is too low to do an orbit (in any normal GA type).

There has to be a way to do this right first time, every time.

Administrator
Shoreham EGKA, United Kingdom

Ibra wrote:

A) Slow down to 60kt (load wings), accelerate back to 75kts (unload wings) and flare

I think we mean different things with “unloading wings”. “Unloading” a wing generally means reducing g — not accelerating.

ESKC (Uppsala/Sundbro), Sweden

Airborne_Again wrote:

I think we mean different things with “unloading wings”. “Unloading” a wing generally means reducing g — not accelerating.

Poor choice of wording, but 1G flying straight and level with Lift = 1*Weight and Drag increases/decreases with various airspeed

Peter wrote:

Surely if you are at 300ft above the runway threshold at 100kt then you have no chance whatever of landing, unless the runway is 3km, or you have a massive headwind

Scenario is more likely to happen on days with massive headwinds (lucky) or hot days with no winds (not lucky), question is what one can do?
Most pilot skills goes to the bin bellow 600ft with no engine: done your best, now it is about damage minimization not polishing to perfection

Orbiting bellow 600ft with no engine is not even an option for para-gliders let alone a fast touring with 100kts “min maneuvering speed”
On type I regularly fly an orbit at 100kts: is 1500ft height/2000ft diameter at 45deg and 1000ft height/3000ft diameter at 30deg
So I am only left with almost flying straight and level while adjusting speeds when I am low

Last Edited by Ibra at 14 Feb 12:23
ESSEX, United Kingdom

MedEwok wrote:

Well in that case I still think the precision of “within 20ft” is still ridiculously ambitious.

Hmmm…

If flying a 3 degree approach, and all other things being equal, being 20 feet higher than intended crossing the threshold, will put your touchdown nearly 400 feet further down the runway than would have been if you crossed at the intended height. I like to have my wheels touching within a hundred feet or so of my intended aiming point, which must mean that I’m aspiring to 5 feet or so of crossing accuracy, so I’m not thinking that a +-10 crossing foot height is not too ambitious, but, to each their own on landing precision.

When I’m training forced approaches, I will state a feature on the surface, where I intend that the pilot touch down. I certainly expect +- 100 feet of touchdown precision, or we keep practicing. My mentors have demonstrated precision in that range, so I aspire to it, and mentor it as a goal for pilot skill.

Ibra wrote:

at 100kts………accelerate back to 75kts (unload wings) and flare

I simply don’t understand this.

Ibra wrote:

Most pilot skills goes to the bin bellow 600ft with no engine:

Then it’s surely time for more practice! ‘Sounds like this is the heart of the problem with forced landing technique, if true. I will fly many flights where the entire flight will be 500 feet or less, and some water flights where I would never climb higher than 250 feet. I would agree that an “orbit” (presuming we’re interpreting that as being a 360 turn) is not advisable during a power off approach below 600 feet, for the simple reason that you’ll have used up most of that altitude just going around the once.

Ibra wrote:

On type I regularly fly an orbit at 100kts: is 1500ft height/2000ft diameter at 45deg and 1000ft height/3000ft diameter at 30deg

I do understand how the diameter of the orbit will be a factor of the speed and angle of bank (I’m trusting your numbers on this), but how does the plane know how high it is, and how is that a factor in the turn?

Last Edited by Pilot_DAR at 14 Feb 16:10
Home runway, in central Ontario, Canada

Pilot_DAR wrote:

I simply don’t understand this.

I mean at if you find yourself in that (high unlikely) scenario you need to do something?
Not necessarily A to E but I am really keen to how YOU would burn that extra energy

The scenario is “300ft height above the runway threshold at 100kts with not much remaining runway”

Last Edited by Ibra at 14 Feb 16:53
ESSEX, United Kingdom

Ibra wrote:

The scenario is “300ft height above the runway threshold at 100kts with not much remaining runway”

Land/crash somewhere else, ‘cause in an airplane, I’ve botched it so much, I’m not going to get it in there!

You can make a mess of many things while you’re flying, and cause the next desired step to be impossible. The key is to apply the skill to have your head a minute or two ahead of the plane, so you see that it’s not going to work out, and make it right (or at least better) while you have a chance.

I focus on training pilots to get it right (within a fairly tight and appropriate range of tolerance), so massive changes in plan, or aerobatic maneuvers are not required to get back on plan. If you have arrived to the runway threshold 300 feet higher than intended, regardless of your speed, you’ve botched it, unless you have planned that for an intended long landing on a very long runway. There’s no point in speculating about a “fix” for that situation, a whole new plan will now be required.

Every flight manual for a certified plan is going to provide the pilot with suitable procedures for that plane, and it’s going have words like “This flight manual is not a substitute for competent flight instruction”. That’s the part about not arriving over your intended landing runway 300 feet too high!

It is worthwhile for fixed wing pilots to thoroughly understand the concept of a height/velocity curve for a helicopter.

https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram

Though fixed wing pilots excuse themselves form considering such unusual concepts, I assure you that this concept applies every bit to a fixed wing as a helicopter, and I can scare the dickens out of you demonstrating it. There are certain combinations of airspeed an altitude from which entering a gliding descent to a power off landing will certainly result in a crash. While you’re considering the main “curve” in the graph, don’t overlook that little sliver on the bottom right. For a helicopter, there are also combinations of high speed, and low altitude from which a gliding (autorotation) landing is difficult. Happily, airplanes fair better with this part of the graph.

Airplane manufacturers are not required to present this information in the flight manual, as helicopter manufacturers are. If I had my way, this graph would be presented for airplanes too. In the mean time, the airplane manufacturers keep their lawyers satisfied by specifying a “best glide speed”, which somewhat (though not wholly) will keep the pilot out of the “avoid” side of the curve.

If, while considering “what you would do if…” for power off landings, anything which comes to mind violates the flight manual techniques, or standard training, or seems to not fit the theme of the H/V curve, you should stop considering it. It’s been done before and the accident investigators wrote a report saying why no pilot should attempt it.

Home runway, in central Ontario, Canada

Interesting to read that wiki description.

What would a corresponding diagram for a SE plane look like?

Administrator
Shoreham EGKA, United Kingdom
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