Shortfield Tips
 

After watching this video http://www.pprune.org/forums/showthread.php?t=218678 it appears this poor guy got his mass and balance incorrect for a shortfield take off. This got me thinking... I'm only a low hour PPL with not a lot of experience outside of long, wide, paved runways. With the evenings getting longer and the weather finer, I hope to fly (and out) of some short and grass strips around the country this summer.

I think it would be helpful if some of the more experienced pilots on this forum could lend us some words of wisdom re shortfield operations.

Answers on the back of a postcard:ok:

Spend serious time with AFM.

Know your density altitude

Pace out AFM ground roll on landing + safety factor from other end of runway and mark it -- if you're not in the air by that point, you have a reasonable chance to stop and reconsider without damage to a/c or people.

Work out distance to clear 50' obstacle and climb rate at density altitude to determine performance margins against terrain, especially if rising.

There is a takeoff performance computer available which can be used to take in account runway slope, weight and wind. Take with big grain of salt.

Remember that overruns are generally less likely to kill you than flying into something:ouch:

Shortfield tips
 

Don't forget that your aircraft flight manual uses results of a new aircraft with a new engine and an experienced test pilot. See the CAA Safety Sense leaflet on performance.

You have probably already read this, but it warrants taking seriously if you are thinking about short strips.
http://www.ais.org.uk/aes/pubs/aip/pdf/aic/4P036.PDF
Beyond that, several flying schools offer farm strip courses (e.g. Clacton aero club) as do some PFA coaches.

To add to the good advice so far: Know your aircraft. Is its short-field performance limited by take-off or landing?

Most spam-cans can land in very short distances, but need more runway to take off from. This is generally a safe situation, since it's generally possible to take off in the specified distance (once all the safety factors have been added) regardless of your experience. In which case, all the advice from others on the thread is absolutely correct.

If you happen to be flying an aircraft which needs more runway for landing than it does for take-off, though, then lots of practice at a field with a bit of extra length is required first. You must be certain of being able to approach to exactly the point you want, at exactly the speed you need. Then measure the distance it takes you to stop on that runway (ideally in still wind, and at the same weight that you're planning on going to your short field), and add a safety factor to that to find your personal landing distances, which will improve as you practice.

One of the major problems when teaching short field techniques is the reluctance to feel what the aircaft is doing rather than relying on what the airspeed indicator is showing.

Make sure you know how your machine feels at low speed and forget all the "add 5kts for the wife and kids b*ll*cks" that most pilots seem to think is acceptable. With short strips you'll come a cropper very quickly with that sort of mentality.

As others have already pointed out, make sure you are aware of how much runway you will actually require and don't try to start with a very short field, but work your way down in size.

There aren't really any "tricks" as such for making short strip flying safer. If you are over loaded or don't treat the strip with respect, then there is no one trick that will keep you in one piece.

Use your common sense and practise, try setting limits on the runway you normally use, for instance touching down at a certain point and making sure you are stopped by another.

Eventually you'll be amazed at how little runway you actually need compared to others not flying "correctly."

Farm strip flying is also great fun and opens up a whole new realm of interesting places to go.

Just don't try short strips in something like a TB10 or Cherokee 140!:ouch:

Fly the correct speeds! These will almost certainly be lower than you think they ought to be.

Target threshold speed Vat = 1.3 x Vso i.e. 1.3 times stalling speed in approach config

If you're not sure about the aircraft's stalling speed at a particular weight you can always stall it at that weight - with an instructor if need be - then you have a reference point for calculating Vat

Then if the resulting figures are lower than you're used to flying the aircraft at, have a practice - again, with an instructor if need be - at flying the aircraft around at that speed to get the feel for it. That should make you feel comfortable that the 1.3 margin keeps the aircraft nicely in a controllable regime.

Same applies on take-off - if the flight manual best takeoff performance says rotate at X knots and climb at Y, then that's what you should do - adjusted for weight of course.

NS

My best "short-field" advice is pretty obvious and I offer it to all who fly into my strip:

If you put your wheels down on the threshold, you will be unfazed!

Even with good clear approaches this requires the flare to happen before the a/c is over the strip.

Any tailwind component can really spoil your day up so do watch what the windsock is telling you.


Stik

stiknruda's advice about the flare is particularly worth noting. You can waste most of a 500m strip on a warm and windless day with a speed that is only slightly too high.

There is no magic to strip flying. It is just very different and far less forgiving than 1000's of feet of tarmac. It is very rewarding indeed but just don't get complacent and treat every strip with respect however long, wide or smooth you have been told it is.

Good luck.

Ditto everyone else: nail the speed on the approach and make sure it isn't too fast. Wind is critical, too, obviously. Going into somewhere really short I find the GPS groundspeed readout a real help. It gives that little bit of extra reassurance that it's all going to be OK.

QDM

One tip I seem to remember being told was that if you haven't reached at least ½ your flying speed by the time you are a third the way down the runway on take off you won't make it, but you should still have time to stop.....

It's true of any approach and landing, but perhaps more so in tighter situations - if you don't like the approach, GO AROUND! Don't try to make an arrival out of a poor approach, have another go.

The big advantage over a glider is that you have got an engine up front that (normally) allows you the luxury of another try (or two)!

Also, if you have made a couple of approaches and still aren't happy - reject the idea of landing! This supposes that you have enough fuel to get back home or to your alternate - so planning for a tricky approach should take this into consideration.

On short field take-offs, my instructors were very keen on not wasting an inch of runway when entering and lining up. Also, be fully conversant with the correct flap settings for the particular aircraft type and model you are flying. Just because one Cherokee / Warrior / Archer uses 2 stages of flap doesn't mean they all do - or that it is true in a Mooney etc.

As many pilots are - and short grass strips tend to intimidate to the extent that they are avoided. This is a pity as you will miss so much in your flying career by staying away. However I'll tell you a story...

Many years ago a pilot I knew quite well wanted to go to a grass strip up north. Having only long tarmac experience it daunted him so he wisely took along an instructor for the first trip and again for the second. Go a few months down the line and he'd established a reasonably frequent routine to this airfield.

One glorious June morning he set off again for B***** and rather grandly stuffed the aircraft through the hedge at the end of the runway. Not a mild prang either - wing ripped off (no fire luckily) and some very shaken passengers.

It didn't take long to see where things had started to go wrong. He'd flown there enough to become complacent and didn't see the odds stacking against him. All his earlier flights had been solo but, on this summer trip, he loaded the dice just a little too much:

1. Temperatures were around +21.
2. There wasn't a breath of wind.
3. He had four people on board and a lot of fuel - probably Max AUW minus the 40min fuel for the trip flown.
4. He'd been there enough to think it was no problem.

The scenario was all too obvious to him in hindsight - as it is to most readers here - but he never flew again.

A flight into a short grass strip has to be thought about carefully - not just the first flight but for every subsequent flight. Conditions change enough to make short strips definite go or no go candidates and it is up to the pilot to do the groundwork for every flight to see if they are in his favour.

Never, ever, get complacent on grass.. Keep your head sharp and they can be a lot of fun..

Jabberwok -

Says it all really - for all of our flying! :ok:

One good rule of thumb is that you must attain 75% of take of speed by 50% of the TO run. If not abort, unless you really really know what you are doing!

Also, better to hold down in ground effect to build speed than to climb out with low airspeed.

And most of all, if all goes tits up, fly a controlled crash landing (if there is such a thing), and don't just stall into crash with nothing but the hope of a lucky outcome!!

SS

Watching the video clip mentioned by ronnie3585 reminded me of a lesson I learned about taking off from narrow short strips. If you start to lose directional control either because of crosswind or improper use of rudder, there is a strong temptation to rotate before you attain the proper speed. Most of the spamcans I have flown will lift of at speeds about 5k below the ideal speed and you are then stuck in a high drag profile and you cannot gain enough height/speed to lower the nose.

Reading AAIB bulletins suggests to me that this is a relatively common cause of take off accidents. In my view, if you start to go sideways before you reach proper flying speed, abort the take off.

There are grass strips and grass strips. Barton for example might be grass, but you really do need to listen to the tower and lining up to wait is often the norm.

Off a farm strip, I see it as one continuous movement, keeping momemtum going when at the threshold, never stopping and running the risk of getting stuck. As has been suggested elsewhere, have a marker on the r/w which indicates the half way point. Know when to abort.

Equally, I do not deploy flap until desired speed has been reached (reduces drag in the roll). Once deployed, get it up sharpish and into the ground effect (for the low wing in particular), once required speed achieved for flight, up you go - for real.

On landing, you must nail the speed early. Always easier to add on a few knots.

Cardinal rule, use an instructor for the first few times.

The Wombat

Another thing's weight. Critical not only on the take-off obviously, but landing too. It puts your stall speed up and can leave you wallowing at speeds where usually you are nicely in control and the plane feels good. Read Stick and Rudder for a nice round-up of low speed handling (and everything else too).

Your aircraft light and your aircraft heavy are two completely different machines, confused at your peril.

Cheers,

QDM

Great advice guys, keep it coming. Hopfully it will keep some of us out of the accident report pages:}

On the point of when it is best to rotate I have heard many differing views. The 172 I fly has will usually want to get airborne at about 55kts (on average of course) however in a shortfield situation i would prefer to keep it on the ground for another 10ks give or take - until it feels right. I dont rotate early as Im not fond of flying in the back end of the drag curve.

[B]Wombat[B] suggested to lift off and fly in the ground effect to bulid up speed. Would it not be safer to leave the main wheels on the ground (provided you have the runway distance) in case of crosswind, gusts, aborting the take off etc, instead of wallowing around in the ground effect in a low speed/high drag situation?

I know there are many variables e.g. wind, weight, temp & pressure etc but is there one "safer" method for take offs?

If you're deliberately keeping it on the ground for another 10kts then that means a greater take-off run and a greater take-off distance. By definition that means you are not using the short field technique, so it is not appropriate for use in a short field situation. Do what it says in the book.
NS

The technique specified in the manual in all nosewheel light aircraft I've flown is something like:

* Configure the a/c as required
* Hold the a/c on the brakes while applying full power. Confirm that the correct RPM & MP is achieved.
* After brake release accelerate & rotate at the speed specified in the chart to achieve Vtoss by 50'
* Retract gear & flap as scheduled
* Climb at Vx until clear of obstacles.

If you choose to accelerate beyond the specified speed(s) you will have a reduced t/o performance. It's a fallacy to think that doing so improves take off performance OR is necessary to avoid operating behind the power curve. Unlike jets, light a/c aren't behind the power curve after take-off & during climb out.

If they were then rotating at a faster speed would improve performance unless the limiting obstacle is very close - in which case the manufacturer would want to include such things in the performance chart to maximise their claims for the aircraft.

If you rotate at a lower speed than specified then you risk being behind the power curve & reducing take off performance. Some a/c have sufficient power to do this and still improve the take off performance. You lose handling quality protections & buffers built into the scheduled speeds however.

There are considerations & techniques that can be used that are outside the manufacturer's manual but try explaining to the insurers & the CAA if you stuff it up & damage the a/c...

<<There are considerations & techniques that can be used that are outside the manufacturer's manual but try explaining to the insurers & the CAA if you stuff it up & damage the a/c...>>

If you stuff it up, then it is a case of whatever you were actually doing you say "I was flying by the book, M'lud." You're hardly likely to say "Yes, I rotated 10 knots too early / late."

Of course, if the aircraft was overweight / out of CG that won't wash!

QDM

ODMQDM you are either not a pilot, or you are dangerously misinformed.

Point (1) GPS groundspeed has absolutely nothing to do with setting yourself up for a good landing, its airspeed thats critical. There is no role for Gps in landing except getting you to the vicinity of the field.

Point (2) The aircraft stall speed increases with the mass of the aircraft, however the Vs quoted in the manual is at max weight

Point (3) Aircraft these days are relatively predictable beasts, refined by geniuses for us idiots to fly. If you stuff it up, then its because you didn't do it by the book - the question then becomes - were you a simple idiot or did you do it deliberately? 10 knots by the way is unforgiveable, 5 knots maybe. By the way, lieing to the authorities is a 'crime involving dishonesty" that at least over here will put your licence, as well as your aviation security identification card (ASIC) renewal in jeopardy

Most schools teach using a reference speed of 1.2 or 1.3 Vs over the fence, however if you are even two or three knots over that in a Cessna you will bounce and float forever.

Best advice is to read the Pilots Operating Handbook and do exactly what it says, otherwise as wiser folks have said, you are your own test pilot.

"bouncing" the aircraft by fiddling with the flaps on takeoff is also a recipe for disaster, you should be concentrating on speed and attitude, not fiddling with a switch or a johansen bar.

do what the manual says no more and no less.

Sunfish,

you obviously have too much time on your hands - almost a thousand and a half of posts in less than two years....

I saw the flaming that you got on Mil Pilots.

QDMx3 (David, great doctor, great GA pilot) really can fly.


Albeit some of the stuf that you wrote was bonzer, some wasn't, so my suggestion would be; read what was being written in context and then you might want to wind your neck in a bit!

Stik

Looking at GPS speed on approach?
Confusion over stall speed?
Advocating lieing?

I think not.

Best advice is from NorthSouth do it by the book

On a more serious note, either do a course, or you might like to consider setting up a sort of "navex' that takes you to five or six different strips.

Wow, sunfish, you need to chill out a bit mate.

The book can quote whatever stall speed it likes. The indicated speed your particular aircraft stalls at is another matter. In my aircraft, which is a Super Cub, the ASI is not all that reliable down at stall speeds and low speed flying is a lot about how the aircraft 'feels'. That is critically dependent on weight. You ignore the weight of your aircraft in strip flying at your peril, both on the approach and obviously on take-off.

GPS groundspeed on approach is an extremely useful indicator when going into a very short strip and here's someone else who thinks so: http://cubdriver749er.com/

Airspeed 45 knots, groundspeed 45 knots is one thing. Airspeed 45 knots, groundspeed 40 knots is a completely different thing. A glance at the Pilot III on the dash when going into somewhere really short can be a reassuring, wonderful thing: picture looks right, plane feels right, airspeed is right, groundspeed is right, let's keep going.

QDM

My apologies QDMQDM, I didn't realise you drive a Cub. I am somewhat sensitive to this issue after learning the hard way about what happens when you land a Cessna even a few knots too fast - $1500 insurance excess on a new firewall.

I am now a strong believer in "the book" and practicing with rearward CG and at gross weight as well. One thing I wish for is that performance charts were of a standardised layout - Cessna's seem about the most comprehensive, I also wish that the use of "factored" (ie +15%) and "non factored" charts was discontinued because its confusing. The most incomprehensible charts I've seen are the good old Tobago's.

Ronnie, one of the problems with asking a question on the forum, particularly a question of such importance as short field take off technique, is that you will inevitably get contradictory answers and as has happened in this case, things do go off at a tangent.

I watched the spat sunfish / QDM and this made me rethink what I told you. In the case of my advice, deploying flap just before rotating into the ground effect is, perhaps, best left until you have a bit more experience. Deploy prior to the roll. In both cases however, get it up into the ground effect at the advised speed. The ability of the aircraft to accelerate when in the ground effect is better than with wheels on the ground. When you reach speed to achieve a positive rate of climb, "rotate" a second time and up you go. Speeds for this in the Archer I fly are 45kts rotate into the ground effect (with 2 stages of flap), increase speed in the straight and level until 65 kts, then climb - still with flap. 500 ft, get rid of flap in stages.

Regarding using a gps to assist with shortfield landings is again, something I would suggest left until you have more experience. Whilst QDM may suggest a "glance" at the gps speed indicator prior to landing, the truth of the matter is that it is one more thing to worry about in what is already a high workload scenario. Leave it until you have a better idea of what you are doing.

When I learned STOL, (and I don't include in learning the five minutes you get during your PPL training) I found a FI who had a good reputation for such things. He started me off on a 600 mtr hard surface and only after I had nailed it (about four attempts) did he take me to the 450 mtr grass strip.

I must confess that I find STOL very very rewarding and get a buzz out of pulling up after a good short field landing. In fact, I am still amazed in how short a distance you can bring an aircraft to a full stop when doing it correctly.

Enjoy

The Wombat

It depends on the aircraft type, too. That's why the best advice is to follow the advice in the book.

I learnt to fly on PA28s. My instructor taught me to do a short-field take-off by holding the controls fully back and getting the aircraft airborne asap, then holding it in ground effect. This technique works perfectly well on a PA28. I then tried it on a C152, and found that holding the controls fully back in a C152 results in a sufficient increase in drag that the aircraft will not get airborne. Fortunately, I was on a long runway when I discovered this.

(Incidentally, although I don't fly PA28s all that regularly any more and never into short fields, I don't believe the technique I've described is what the book says, so it's not what I would teach either. But it does demonstrate nicely that a technique which works well on one aircraft type might not work on another.)

FFF
--------------

I've just watched the videos on that site, and am staggered that he can land in places like that! How on earth does he know he can take off again??

I should have clarified when talking about using GPS groundspeed that most of my landings are in places without windsocks. Most of the time you can assess wind directly from track across the ground, but when the wind is light it is useful to have a GPS groundspeed readout.

QDM

There are many possible variables to take into account, and what might be right on one day, wrong on the next.
Getting it airborne, or at least getting the nosewheel up early, is appropriate for long grass or soft (draggy) surface. Once free of the drag, accelerate as stated above (to what airline pilots, who do this every time they fly) call v2, then climb.This should take only a very few seconds. On a firm strip, that's not necessary, and in fact can be counterproductive, as the increased drag produced by high AoA wings will reduce acceleration.
For landing, as stated above, speed control is all-important. Since there is reduced margin to counter windsheer etc, very wise to become sensitive to that phenomenon, at those low speeds, in a safe environment first. Practise doing minimum-speed steady-rate descents at altitude. Chuck in a turn or two. Learn to feel when the controls get sloppy.(Or sloppier). Most light singles have a mediocre power/weight ratio, so get a negative gust on short final, with a heavy load, at min speed, be very ready to use all the throttle. For this reason, deselect carb heat at least above 100'.
Some lighties (eg the 172) were originally recommended to climb for obstacle clearance at 1.2 Vs; this changed to 1.3 when the certification requirements changed about 20-25 yr ago. My point being that if you are capable, the aeroplane can be made to perform better than the book says it can. I've tried this and it works. (Not recommended in a slab-wing cherokee, though.)
IMO the 182 pilot in the sad video dragged it off the ground prematurely, losing directional control in the process, and was partially stalled for about the next 6 seconds (I reckon the right wing drop after liftoff was the beginning of a wing drop stall) and once clear of the buildings was pretty
much completely stalled.
Best advice, go to a few strips with a good instructor. Get happy in operating into them,in a variety of weight/weather conditions.
What sort of a/c is it you'll be using?

Just watched the video of the Super Cubs landing on the gravel spits...WOW my jaw is still on the floor!
How do they take off again? Especially the guy that used the river to begin his landing roll!

It was a 172R but just upgraded to a 172SP. Its better for STOL as you really notice the extra 20hp on take off.

Re my previous post, maybe I over estimated a bit when I said I would hold it on the ground for an extra 10kts, its more like five.

I cant but agree about nailing the approach speed. A flying buddy of mine recently left very big skid marks on a very small runway! Was too high and too fast but committed anyway...bloody stupid of him but at least he walked away with no damage done.

The POH in my PA28 says absolutely nothing about short field take off. All it says is that the normal T/O procedure is, no flap, full power and rotate at 74 mph. This is the configuration for the take off performance data in the POH.

However, on grass, I was trained to use 2 stages of flap , rotate at 65 mph and accelerate in ground effect to 74. Many years ago I was taught, in extreme cases, to increase flap to full at 60 mph and then gradually reduce back to 2 stages while accelerating in ground effect. I was also taught this, incidentally, as a rough water technique in a Cub float plane. I have never done it without an instructor in either case.

Can anyone tell me what effect the use of 2 stages of flap is likely to have on take off distance. I still use the normal calculation in the book because its the only one I've got.

As a general rule, flap allows you to rotate at a slower speed, which has the effect of reducing the ground roll.

However, the extra drag from the flap will reduce climb performance. (Remember that an aircraft climbs because it has more thrust than drag - so any extra drag reduces the amount of thrust available to climb with.) Which is why many aircraft's POH give the option of different amount of flaps depending on whether there are obstacles at the end of the short field (use less flap) or not (use more flap).Strange - I'm sure mine does, but as I said, it's been a little while since I last looked. I'm pretty sure it suggests 2 stages of flap and a lower rotate speed..... but maybe my memory has failed me?

FFF
---------------

All aircraft are different, natch.

In the Super Cub full flap pops you off the deck into ground effect like a cork and then best angle climb is at a truly terrifying 45mph with full flap. What happens if the engine fails in that attitude at 100 feet does not bear thinking about.

QDM

Pulse1

The book doesn't specifically mention a short field procedure because the one given *is* the short field procedure. The technique specified meets certification criteria about handling qualities, speed buffers etc. Other techniques may get the a/c off the ground earlier - although not necessarily clear an obstacle further along, or may clear a higher obstacle nearby but usually do so at the expense of losing protective speed buffers or reduced handling qualities.

Landing techiques have the same caveats.

Do other techiques work? Sure, but you'd better be very sure of your skills & judgement. My previous job required me to fly into strips as short as 380 m, often in strong turbulence & with obstacles nearby, sometimes at night for air ambulance in rather nasty weather. There are times when operating on the very edge of the performance ability of the a/c will get you in or out, but there will be an increased risk.

For goodness sake, do it by the book!

For what its worth, here is what my Piper Arrow manual says:

"Short field takeoff with an obstaccle or soft field differs slightly........Flaps should be lowered to 25 degrees (second notch)....allow the aircraft to accelerate to 50 to 60 knots depending on aircraft weight and rotate to climb attitude. After breaking ground accelerate to 55 to 65 knots and select gear up. Continue accelrating etc etc.

As for landing, all they say is for short field is full flap and enough power to maintain approach speed (75 knots). Reduce speed during the flareout and contact the ground close to the stalling speed (55 knots). It then goes on to talk about holding the nose wheel off, putting weight on the mains and raising flaps. It then cautions about using partial or no flaps in high wind or crosswind conditions.

From memory the Warrior manual says much the same thing, except I can't remember if you use flaps at all.

Please be very very cautious about instructors who show you a "special" technique unless they are old and very experienced and can explain in detail how and why the procedure works.

Remember that most training is done at well below max weight and what works when your instructor demonstrates it may not work so well when you have Mum and the two kids on board.

Please note that in a Cessna 210 (laminar flow wing) if you rotate too early you will simply traverse the entire length of the airstrip before hitting the fence.

There are a few other interesting ways to get killed, like getting a little too slow on approach and falling out of the back of the drag curve.

As for applying flap during the takeoff roll, you are asking for trouble. One day you will either forget because you are dealing with some other problem, or something will occur just as you reach down for the switch or the bar. I've already nearly been killed by a sticky Cessna flap switch and I don't take my eyes off the runway just to check if the flaps are extending. Things can happen very fast and you don't need to add unnecessarily to your own workload pulling this trick. The gravel strips I've used require all your attention just to keep the aircraft pointing in the right direction and on "centreline"

For goodness sake, use the book!