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

Welcome back @Pilot_DAR

I think the idea behind the high-key low-key system is to be in a position where a landing is 100% always assured – provided you are in the high-key position at (or above) the required height.

The bit I still don’t quite get is how do you reach that place if gliding from very far away; from a possibly much greater height.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

The bit I still don’t quite get is how do you reach that place if gliding from very far away; from a possibly much greater height.

Well with the L-39 it was a huge part of the checkride. There are lots of ways to do it but you have to wing it a bit. The idea of high and low key is they give you points to get to – essentially they create a structured plan. You need to judge where you are, what the wind is doing and the best way to make sure you get there at or a bit above the altitude.

Of course the problem in a real flameout or engine failure is you can’t be too high to land but definitely cant land short.

EGTK Oxford

There are lots of ways to do it

I wonder what the ways are?

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

I wonder what the ways are?

To lose height in an aeroplane?

EGTK Oxford

To lose height and end up at the correct height at the correct place (high key)?

As I see it, one cannot just orbit down because each orbit is going to lose a lot of height, so the “resolution” of the process is too coarse.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

As I see it, one cannot just orbit down because each orbit is going to lose a lot of height, so the “resolution” of the process is too coarse.

I tended to. A couple of hundred feet doesn’t hurt. You need to know the performance of your plane of course. S turns. Dropping gear and adding flaps also help adjust approaching final. You can push the nose down and trade altitude for speed and lose the speed later.

EGTK Oxford

We have have wires totally crossed Jason but I do know how to fly a glide approach and so do most people

The current topic is how to arrive at the high key position.

Or are you saying that if you arrive at HK say 3000ft too high (I am sure the L29 loses a lot more than 200ft in an orbit ) and another orbit would place you too low, you depart HK 3000ft too high and make the adjustments as required on the way to LK and final?

Administrator
Shoreham EGKA, United Kingdom

It is exactly the same principal as arriving at the threshold at 0 feet. If you can’t orbit, you could slightly widen out from the runway. Do some S turns etc.

It is a glide approach and the concept of high key and low key are just a system to realise that. Buster has some good techniques in his book for very long distance glides, but I tend to take the view that there are no points for style if you lose an engine and the most important thing is to make it work.

Last Edited by JasonC at 04 Jan 18:50
EGTK Oxford

Apologies for surfacing so late in the discussion, had bad time as of the Friday before Christmas, my wife had an high speed accident on the A1M, had to look after her and also did not want to turn friends away so had to prepare everything on my own. Luckily the car saved her and she suffers of bruises and a broken finger

172driver wrote:

Ben wrote:
and kept the 45 degrees all the way down and this also dictates the turning point to base and final.
That may work on a low-wing aircraft, it won’t on a Cessna (or other high wing).

Can you please explain why? The wing tip might hide your approach only during the turn or is there something else?

In explicit response to Peter’s question, for me, the obvious answer is similar to Jason’s response, you just ‘bend’ or ‘straighten’ your approach to the point.

One example: In the event of an engine failure at 10k, you hit ‘nearest’ on the GPS and it directs you to a point midfield on the nearest runway (which you can make). You are gliding down from 10k and you want to be at 2k over the field to do some sort of circuit (high key). Most aircraft are going to glide down at less than 1000 ft/min; this means you have lots of time (8 minutes!). Surely you will use some of that time to do your checks, try a restart, whatever.

As you start to get close to your high key you are going to have to clear you head and make some decisions:
- If you are really high, you could orbit.
- If you are pretty high, but not enough for an orbit , then you could aim a bit to the right or the left of your high key. As you get closer you are going to have to use your judgement, if you are back on target altitude turn towards the high key, otherwise, stay wide.
- If you are only a bit high, you could maintain status quo, or slip a bit.

A combination of these should get you to the high key. The problem comes if you leave it too late, because it is difficult to loose a lot of elevation in one spot. Another problem is if you aim too far away from the field ( you don’t want to get caught by other variables, say unexpected wind direction). After a couple practice runs, I think you can get a feel for it.

Maybe it is just me, but I do a variation of this on every approach. It could be because I learned to fly in Vancouver, you are always coming in at 10 or 12k to clear the mountains and have have to land at sea level (often a glide descent). I am always planning to arrive at the circuit height. I normally just watch the GPS ETA, if it says 10 minutes to run, and I have to loose 9k then it is a 900 fpm descent (I used these numbers for easy math, I prefer 500 fpm). If I really cock it up, or ATC keeps you high, occasionally an orbit is required, but no big deal.

You have to do a ‘spot’ (accurate) power off landing for your Canadian CPL, so I have done lots of practice and tried a few techniques:
- Get to the high key and then do a sort of figure 8, with a lobe on either side of the runway centre line
- Join overhead and orbit, adjusting your final orbits so that you meet the key points.
- Aim for a point mid-downwind at 1500 feet and work it out from there. (Obviously if you are over the field at 2k, you can make it to mid-downwind at 1500 feet).

Each of these techniques works with practice, I was taught the figure 8 method in my PPL, but am not fond of it. I understand some gliders (I haven’t done any soaring) prefer the orbit method; I can see this, because if you are orbiting the field it is virtually assured you will be able to land on it, no matter how bad your approach is (even if you end up doing it backwards, i.e. downwind).

I am most fond of the mid-downwind point, because it stops you from being too close and too high, but the high key points are designed to help you with this.

Last Edited by Canuck at 05 Jan 15:24
Sans aircraft at the moment :-(, United Kingdom
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