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-   -   PFL-Field Choice (https://www.pprune.org/private-flying/470306-pfl-field-choice.html)

Grob Queen 28th Nov 2011 19:03

PFL-Field Choice
 
Had my first briefing on PFLs from my QFI yesterday. We weren't able to fly as the wind was way beyond limits so I haven't yet tried it in practice.

However, field choice. I was obviously briefed on the dos and don'ts, but taking into consideration the obvious requirements to avoid obstacles, Rule 5, wind direction etc, I wondered, what would be the preferred choice of crop or stock for fellow ppruners to land in? and why?

Oh and for this scenario, there is no fallow field or hard standing to land in!

billiboing 28th Nov 2011 19:14

WiSSSSO!
 
The way I remember is

WiND- Which way is wind blowing- if high enough remember there are more fields within gliding reach downwind than upwind!. Pick a field into wind!
Size- Look for the biggest first!
Slope- Landing uphill ok provided not too steep- land downhill and ya wont!
Surface. Short crop ok- land with furrows, Rape- forget it!
Stock- Avoid the cows!
Obstructions- Look for wires (or the poles at least!)

'India-Mike 28th Nov 2011 19:37

Shape, size, surface, slope, surroundings. Rule 5 doesn't feature in my decision-making as it won't when one happens for real. And I always choose one that I could get into if I had to, and treat every PFL as if I might have to use the field should the engine not respond for the go-around.

On the Chipmunks I instruct in this is a not uncommon occurrence (despite mentioning it during the briefing) as the front-seater can catch the mixture with the cuff of his nice flying gloves, advancing both throttle and mixture lever together for the go-around (on the Chipmunk forward mixture=lean mixture!)

BackPacker 28th Nov 2011 20:01

Any field that looks reasonably "clean", is easily reachable from my present altitude and is long enough, preferably into the wind, is OK.

Don't go through a long winded decision making process but trust your instincts. And unless the field turns out to be completely hopeless, stick with your decision. A good landing in a bad field is more survivable than a bad landing in a good field.

Also remember that as soon as the engine quits (for real), the plane is no longer yours but belongs to the insurance company. The objective is to be able to walk away, not to save the plane.

B4aeros 28th Nov 2011 20:14

Rule 5 doesn't apply to actual landings.

Stock is never good - if at all possible, avoid fields with livestock.

Crop fields are OK provided:
  • you land parallel with the wheelings (deal with any crosswind)
  • your wingtips & elevator are higher than the crop.
The idea is to round out & land on the top of the crop - it might end in a heavy landing but the undercarriage can cope with it as long as you don't go over any deep ruts during the ground run. Tall crops catching on the Grob's low wings can result in a damaging groundloop.

The only way to judge crop height is to assess how much of the ground you can see through the crop. If you can clearly see the earth, the crop is still small. If you can only see the ground in the tractor wheelings, the crop is maybe 2 or 3 feet high. Once the crop covers the wheelings, you should expect a low wing aircraft to be damaged during the landing, but the pilots should be OK.

A couple of years ago I saw a Cessna in an oilseed rape field. The crop must have been about 4 feet tall, almost to the top of the cowling. The clearly visible ground run was impressively short but the aircraft looked to be undamaged. That was early summer, when the crop was still green. Once oilseed rape turns brown it becomes a thick impenetrable mass that would probably flip any aircraft upside down.


thing 28th Nov 2011 20:31

As everyone else has said. I took me ages being a glider jock to get it into my head that a sucessful field landing in a powered aircraft is one where you and the passengers walk away unhurt; whereas a field landing in a glider is just a normal landing where any damage to the glider is bad news.

I was always trying to do a 'glider' field landing when I first started doing PFL's instead of looking at maximising the chances of being unhurt and sod the aeroplane.

mary meagher 28th Nov 2011 20:56

Quite right. When landing a glider in a field, you have plenty of time. Deciding at 1,500 feet, you have at least 30 to 1 glide ratio, and so about five minutes to plan and decide. No messing around trying to call Mayday, or attempting to restart the engine. So the choice of field can be carefully made according to the rules mentioned above.

But if the donkey stops in a power plane, the field picks you. Might even be a rooftop, or a clump of trees. Main thing, EFATO, DO NOT TRY TO TURN BACK TO THE AIRFIELD. It is the spin off the lousy turn that will spoil your day. Possible to land and survive on nearly any kind of terrain, forest, lake, housing estate if you land with full control of the aircraft, as slowly as possible.

However, using a power line as arrestor cable tends to spoil the approach.

Big Pistons Forever 29th Nov 2011 00:51


Originally Posted by BackPacker (Post 6831804)
A good landing in a bad field is more survivable than a bad landing in a good field.
.

Words to live by. Flying schools IMO spend put far too much emphasis on some elaborate protocol for selecting a field, especially arcane discussions about what kinds of crops are best, how to deal with furrows, water puddles, farm animals, etc etc etc. The criteria I teach for for field selection is
simple

-Close (so you are sure you can make it)

-Open (as in no obstacles on the approach or big rocks walls ditches etc on the field)

-Big (to give you more options if you are high or low) and

-Flat, in that order.

And remember better is the enemy of good enough. Go to the first "good enough" field you see and then concentrate on flying the aircraft to your chosen touch down point.

Finally a personal pet peeve is flying schools spend a lot of time about what to do when the engine fails but hardly any time talking about what to do with a partial power loss, which are far more common than total abrupt engine failures. In any case about 80% of all cases of total loss of engine power are directly caused by the actions, or inactions of the pilot, so I think flight schools should spend a lot more time working on students preventing the engine from stopping in the first place, rather than just what to do when the engine suddenly stops.

A and C 29th Nov 2011 05:05

Rule 5 the realistic practice killer
 
As an instructor I am carefull about the location of my students PFL's but if the practice is going well and into a good clear field away from people or livestock I am more than happy to go around at about 50ft.

Doing so lets the student know that they could have got safely into the field, having a blank "not below 500ft rule" makes the whole practice a joke as the student is never sure that he/she would have got into the field without having an accident.

Remember Rule 5 is a rule, not being able to land an aircraft without power is a death sentence.

Pilot.Lyons 29th Nov 2011 07:37

When i did got about 100ft from field and thought.... "is he going to tell me when to power up?!)
The wind was bad.... From my ass

But now, i wouldnt have wanted it any other way
Just like when i was going solo on a runway with 12 inches of snow and the only way you knew where to land was from my tyre tracks from take off!

I enjoyed training more i think

IO540 29th Nov 2011 08:20

I also think that, taking the "90+ % case" of flying over countryside, the best thing is to turn roughly into wind (that alone is likely to make a huge difference to the energy which one needs to lose on landing) and pick a series of fields that are lined up along your heading.

It is much easier to control azimuth than it is to control your rate of descent, the latter of which will in any case be largely determined for you.

The more technical method, also taught by the military (low key, high key, etc) is to pick a field nearly below and follow one of several specific procedures to fly a circuit into it. That's great if you are good and current and practiced, and has the advantage that you are better placed to survey it for obstacles etc, but I think most PPLs will not make such a good job of it when under pressure.

I know which method I would pick.

chrisN 29th Nov 2011 09:53

One thing to add to the above. It was posted that “The only way to judge crop height is to assess how much of the ground you can see through the crop. If you can clearly see the earth, the crop is still small. If you can only see the ground in the tractor wheelings, the crop is maybe 2 or 3 feet high. Once the crop covers the wheelings, you should expect a low wing aircraft to be damaged during the landing, but the pilots should be OK.”

There is another way. If the wind is significant, wheat and barley (and even long grass) show waves of windswept tops running across the field. If you can’t see them, the crop is short (or it is not windy). If you can, the crop is long enough to make at least some difference.

Regarding stock, avoid if possible.

Horses – the landowner will be really upset if they are expensive and/or in foal. You may thtink horses are expendabale compared with people, but the owner may not agree. I was told once that a prematurely dropped foal could cost £500,000. Dunno if that’s true.

One cow in a field is not a cow, it’s a bull. Avoid if at all possible. If not, once out of the aircraft, hide behind it until the bull seems unlikely to be interested in you.

A lot of cows in a field may include a bull. (Been there etc.) Avoid eye contact with the bull should you have to go into such a field. Cows sometimes change where they want to eat, and if you pick the empty side of a field to land in, they may suddenly move into it. Happened to a friend of mine. Ditto sheep – and that happened to me once. (We both just got away with it).

The crucial thing, as said by others, is to maximise safety of people, not the aircraft. (While glider field landings are normal, and usually uneventful, in the end it is still a piece of sporting equipment that can be mended or replaced. People not so easily.)

In extreme cases:

If the field is short, it is better to hit the far end slowly, having lost some energy, than hedge/wires etc. at the near end at flying speed.

If landing towards unavoidable trees, aim the nose between them and let the wings hit the trunks.

Hedges are not as soft as you might think. In July, a glider pilot had to choose between a groundloop or going into a hedge. He chose the latter, thinking it would cushion his arrest. Wrong – the nose of the glider hit a stem/trunk of one of the bushes, and resulted in really bad leg fractures. A ground loop to put a wing into it (if it even got that far) would have damaged the glider but probably avoided pilot injury (been there, too.)

(I have landed in a glider in over 100 fields, so write with a bit of experience, though not all apposite to power emergency landings.)

Chris N

Gertrude the Wombat 29th Nov 2011 10:44


I also think that, taking the "90+ % case" of flying over countryside, the best thing is to turn roughly into wind (that alone is likely to make a huge difference to the energy which one needs to lose on landing) and pick a series of fields that are lined up along your heading.
Round my way this is known as the East Anglia Method:

(1) Set up a circuit

(2) Work out which field you are going to end up in

(3) Tell the instructor/examiner that that's the one you've been aiming at all along

jollyrog 29th Nov 2011 12:49

Even better, just fly a circuit, ignore all the fields and draw a mental picure of your your favourite home aerdrome approach. Fly it as you would.

At 500 feet, ask the instructor if you should apply power now. Apart from that question, don't communicate with him at all during the circuit.

Works every time.

Heston 29th Nov 2011 13:04

Which is why instructors are trained always to ask the stude to nominate the field at the start of the exercise!

Gertrude's East Anglia method works for real, of course, as well as for PFLs (at least where there are lots of big fields - hence the name)

H

Pull what 29th Nov 2011 13:04

GQ, to answer your question-crop or stock.


Stock is never good - if at all possible, avoid fields with livestock.
Not quite correct- sheep & horses are no real problem if they move out of the way! Avoid ostriches, cows & bulls.
Crop is OK if you land with the furrows, if you land across them you will probably overturn.
Most students seem to think they need to pick a field that looks like a 1000 metre private strip and is perfect-you just need the best clear area which is not going to damage you!

BackPacker 29th Nov 2011 13:32


sheep & horses are no real problem if they move out of the way!
In case of an engine failure your aircraft has just gone completely quiet apart from some wind noise. And even if the animals see you coming, they will probably not recognise you for what danger you are and move out of the way. So I would not bet on animals conveniently creating a nice clear landing strip for you in your chosen field.

So in that respect any type of livestock in the field is bad news, unless you manage to avoid them.

Having said that (but now I'm a glider pilot talking), if you have the choice, sheep and horses are better (less bad) than cows and ostriches, indeed. Not because of the damage during the landing roll, but because cows and ostriches are very inquisitive and will damage the aircraft while trying to investigate what just landed in "their" field. Horses and sheep are apparently less inquisitive, or are more easily shooed away. At least, that's what I've been told - I have yet to make my first outlanding.

Genghis the Engineer 29th Nov 2011 13:54

I did a precautionary landing into a field full of cows once, when I returned to fly out a few hours later the prop had clearly been used as a scratching post and the exhaust as a lick.

There was, I think, an Auster a couple of years ago which did something similar and most of the fabric got eaten off.

G

thing 29th Nov 2011 15:10

Cows are notorious for eating fabric/dope finishes.

shortstripper 29th Nov 2011 19:12

Yep ... cows have very abrasive tounges! They're very inquistive and will destroy an aircraft in seconds! However, they're lovely and really don't mean to spoil your day. Once they're bored with the wreckage you'll find them layed around chewing the cud wondering what the next distraction will be :\

SS


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