short Field in a 172 is frustrating me !!! HELP

[Dyski]

Hi there,

Getting ready for the CPL ride but those ShortField landings are getting frustrating. The 172 seems to want to float forever and ever!!!

I usually do a shallow approach,drag it in to the threshold and chop the power just before the threshold (Aiming to touch down on the numbers) however it floats about 200 feet past the numbers.

I know i can always idle it a little earlier but my worry is the airplane might drop and wind up short of the runway on the grass.

What is a good practice for the FLIGHT TEST ! somehow 100ft tolerance seems too tight to me.

Any help would be appreciated !

thanks

[tired of the ground]

First of all, if you're trying to learn how to do a short field landing you should choose a point that is ok to land short of. Those thousand foot markers are real convenient (depending on the length of runway). Your instructor should have taught you this however.

It really sounds as though you are approaching too fast if you're floating a long way. Part of the short field portion of the CPL test is that you must calculate 1.3 x Vso and use that speed to fly the short field landing.

What speed are you approaching at?

[mathewc]

Ok, here we go:

DON'T CHOP AND DROP! I have heard from both instructors and examiners that the chop and drop will not get you a great mark on that item. Instead, find a power setting that will take you on a smooth decent profile down to your flare point while still maintaining your 75-100ft over the threshold. This means a more controlled decent starting from a higher altitude, not coming in low and dropping in. In real life would you want to come in 50ft at a low airspeed over trees and then drop in? Probably not.

FULL FLAPS I'm pretty sure that's a gimmie though.

MAKE SURE YOU HAVE THE CORRECT AIRSPEED! If you're finding that you're floating too much, pay attention to your airspeed on approach. You should stay around 60KIAS for a 172 at gross, and a bit less for less weight (you will need to calculate it all out for your CPL exam).

PICK A BETTER POINT! Just because you have an obstacle at the threshold doesn't mean that you should expect the aircraft to settle on just after the numbers. When practicing mine, I figured out that even the 1000ft markers were often too short to put the aircraft down on. If you can pick a more accurate point that the aircraft will realistically settle on you will be in better shape. Remember, the examiner will ask you for a touchdown point, not the closest point to the threshold that the airplane could possibly touch down at. Be realistic about it.

At touchdown apply full back pressure, raise the flaps, and apply full breaking power without locking up. The 172 will stop very very quickly.

Hope this helps!

[crazy_aviator]

in flight training, a true short field landing isnt demonstrated or practiced, In the real world , power is incrementally ADVANCED, the shorter the field is AND in the flare, power isnt reduced , BUT acvanced further!!! The back side of the power curve isnt practiced much !!!

[taylor498]

in flight training, a true short field landing isnt demonstrated or practiced, In the real world , power is incrementally ADVANCED, the shorter the field is AND in the flare, power isnt reduced , BUT acvanced further!!! The back side of the power curve isnt practiced much !!!

Are you suggesting the short field approach should be done in slow flight? I guess you're trying to live up to your username.

----

Like others have said... don't pick your point right at the numbers. It leaves you no tolerance to land short! (unless you feel like doing your soft and short field landing at the same time ) For CPL short field landing, your tolerances are +100/-50 feet, take full advantage of it. Pick the 500 foot marker, the 2nd or 3rd white centerline... whatever you want. Just not the threshold/numbers.

The aircraft will inevitably float a little with any approach... because it is starting to enter ground effect once within a distance of roughly the aircraft's own wingspan above the ground. At about a half wingspan distance, the induced drag is reduced considerably. Less drag = more energy = more "float" Any extra airspeed you are carrying will also contribute to float.

Having said that, the most important point to take away from this is to ask your instructor. Be very careful about any advice you read on an anonymous online forum. (including mine) Chances are your instructor is more than willing to help you with your questions, in addition to knowing all the details of the problem you are trying to solve.

[crazy_aviator]

Taylor, I have been flying for 25 years without any accident, infraction or incident ! Have you ever flown the mountains or done an aerobatic maneuver? My handle doesnt necessarily match my knowledge, ability or professionalism in aviation ,,

[iflyforpie]

Advancing the power to get into the back side of the power curve isn't the best thing to preach to a student practicing short-field.

The first thing that happens when you advance the power is your trimmed speed is reduced (don't believe me, try it!). The plane loses responsiveness and large airspeed excursions are inevitable.

I usually do a shallow approach,drag it in to the threshold and chop the power just before the threshold (Aiming to touch down on the numbers) however it floats about 200 feet past the numbers.

The opposite happens when you chop power! The plane actually speeds up if unchecked with the yoke. A shallow approach also means less flare--another airspeed robbing maneuver. Many people trying to spot land do a shallow approach, but this winds up being counter productive (and potentially dangerous).


The best thing to do is set up the plane for 1500 RPM, 55 KIAS and 40 degrees of flap. 60 KIAS is too fast. It is stable as a rock at these speeds (when I am lighter I approach at 50 KIAS) and requires minimal adjustments with the throttle if you are doing a higher than three degree approach (four whites--you should be for short field).

Gradually reduce power as you are coming over the fence and increase back pressure-keeping your aim point about 200 feet in front of your touchdown point. If the stall horn comes on early, just add a smidgen of power. But it should come on as the wheels touch.

You should not be looking at you airspeed after the end of the runway passes under your nose. At this point and you should be controlling altitude with the yoke and letting airspeed decay.

[Big Pistons Forever]

Too fast is a common mistake. In a C 172 with one person and half tanks I use 60 knots bleeding the speed back to 50 knots on short final. Aim for just short of the touch down point and smoothly reduce the power to idle as you flare (The nose will try to drop as the power comes off so be prepared to firmly rotate to the landing attitude). The aircraft will make a nice tail low landing after minimal float every time. One of the problems with the way slow flight is presented at FTU's. 55 kts with 10 flap is not slow flight. I get all my students to try to get the airspeed indicator to read zero. I expect them to manoever the plane including 30 deg banked turns with the stall warning horn going continuously. With a bit of practice the airplane will tell you by the way the controls feel and the aircraft performance exactly where you are in the power/drag curve and how much margin you have. Only with that knowledge can you IMHO make truely safe short field landings.

[AuxBatOn]

Don't try to grease it. Put it down firmly enough, but not too much (so you don't bounce). That way, you are on the ground sooner, meaning you can use the brakes sooner and by landing firm, you actually reduce your ground speed by dissipating some of that energy into the ground via the wheels.

[Blue Side Down]

Lets not try to make this too complex-

1. Drag pulls you out of the sky faster than anything else- learn how to use it- flaps and slipping makes getting into short fields easy. Power is the only thing that fights against drag, so don't use it!
2. Aiming short of where you want the wheels to plant should be a given- just pick a sensible aiming point.
3. Practice makes perfect. Practice power off approaches using some flap and enough slip to put the plane where you want it every time. If you don't hit the mark the first time, try it again until you do. Skill improves as more gas is burned.

voila

[hairdo]

At touchdown apply full back pressure, raise the flaps, and apply full breaking power without locking up. The 172 will stop very very quickly.

Smidge of a problem if you do it in that exact order. See, you're aircraft probably has a bit of flying capability left when you touch down (unless you did a full stall touchdown), so the aircraft might just decide to hop back off the runway, and this has the tendency of eating up runway. But if you apply the brakes right after touchdown, then follow with flaps and back pressure in quick succession, followed by more brakes (more weight on the wheels, more braking capability), you should be able to achieve a pretty short rollout.

Biggie with the float is the approach speed. Set the aircraft up at POH recommended speeds for the weight, and as you are approaching short final (at least by 50ft AGL), slow the aircraft to 1.3Vso (as per commercial formula). If you are feeling ambitious, fly the whole approach at 1.3 Vso, but it's really not necessary, and it restricts your vis. That will help to keep any float to a minimum. Don't worry to much about a firm landing (not to be mistaken with a bounce). The greaser is not the goal, but if you can do that AND nail your touchdown point, BONUS!!!

And perhaps you are aiming for a point that is too early. Consider how long the runway (or simulated runway) is, how long you need to safely stop the aircraft, and work from there. If you have a 3000ft runway, and your aircraft needs 2000ft to stop safely, I doubt you really need to land on the threshold. Perhaps the 500ft marks would be good (if they exist on the runway), as you have a 500ft buffer on each end.

Anyhoo, that's my 2 cents.

[FlaplessDork]

I usually do a shallow approach,drag it in to the threshold and chop the power just before the threshold (Aiming to touch down on the numbers) however it floats about 200 feet past the numbers.

This is a sure fire way of killing yourself and come up short. Chop and drop will get you a slap with a ruler if you try that with me. Fly anything heavier and you'll drop like a rock.

One little trick I use is to take your Landing Distance over 50' and subtract your Landing Roll factored for winds, weights, alt's and temps. That is the distance before your touchdown point to aim to be 50' in the air in a stabilized approach. Do a normal approach and flare to that point and adjust your timing of pitch and reduction of power to make your planned touchdown point. Use the runway centerline stripes and markings as a guideline to measure distances, each stripe is approximately 100' in length, and the space in between is 100'. You make also have touchdown zone, and 1000', 1500' markings to use as a guideline.

Another thing I do when training for shorts, is never have the student land on the same point. Teaches them to use the correct judgement in planning approaches and flares. If they use the threshold as a guide for the approach and flare, it will show up really quick. Lucky we have a very long runway, and sometimes I will get them to land at the far end of the runway with only enough room to land on the last circuit of the day (safety is key on this one, I dont recommend trying this if you're unsure of the student or airplane performance) to provide that learning factor of intensity.

[FlaplessDork]

in flight training, a true short field landing isnt demonstrated or practiced, In the real world , power is incrementally ADVANCED, the shorter the field is AND in the flare, power isnt reduced , BUT acvanced further!!! The back side of the power curve isnt practiced much !!!

Are you suggesting the short field approach should be done in slow flight? I guess you're trying to live up to your username.

I believe he is refering to the flare short of the runway. Most of my short fields landings I carry some power in the flare and time it right and I will actually touchdown much slower than a power off flare. Your stall speed is substantially reduced with power. The twins I fly, you'd never get away with the chop and drop. You'd break the nose gear, and worse come up short.

[AEROBAT]

in flight training, a true short field landing isnt demonstrated or practiced, In the real world , power is incrementally ADVANCED, the shorter the field is AND in the flare, power isnt reduced , BUT acvanced further!!! The back side of the power curve isnt practiced much !!!

I agree 100%. You touch down at a much higher angle of attack and when you pull the power you really quit flying. Some planes I have flown I noticed that if you touch down tail wheel first with a bit of power I can land shorter than than a power off three pointer. Not to be confused with "dragging it in" at a shallow approach angle. Basicaly I round out a bit higher and use power to arrest the sink.

I have heard it said that a 172, when light, will float 100' for every 2 knots above the ideal approach speed.

[deflux]

in flight training, a true short field landing isnt demonstrated or practiced, In the real world , power is incrementally ADVANCED, the shorter the field is AND in the flare, power isnt reduced , BUT acvanced further!!! The back side of the power curve isnt practiced much !!!

I have heard it said that a 172, when light, will float 100' for every 2 knots above the ideal approach speed.

I can definately believe that...

The first instructor I ever had, had me flying 70kts in a 172 with full flap on a short field landing. POH says 60kts..

The next instructor I had explained why that was BS and suddenly everything got alot easier..

[AEROBAT]

The first plane I owned was a 150 and the stall horn would go off long before it ever got close to actually stalling. I was getting the annual done and asked the AME if he could adjust the stall horn. He just laughed and said duct tape it if you don't like going off early. So I did!

Then I learned how to feel for the airplane stalling, getting feed back from the controls rather than an instument. In my opinion a lot of Cessna AC tend to have stall horns that go off too early. I used to fly a 337 and had no problem landing without a lot of float. The other guy who flew it used to come in too hot because he would panic as soon as the stall indicator started to go off. One day he ran it off the end of a 3000' runway. The runway was icy but in reality he should have had no problem.

[Dyski]

Thanks a lot guys,

That was great advice, i resolved it by taking I flyforpie advice and it works. Thanks all

dyski

[ywgflyboy]

Two options.

1. Switch to a Piper Cherokee if available. They sink like a rock
2. When you cut the throttle what happens? The RPM does drop but it takes time. The more power you come in with, the more you have to loose when you "retard" the throttle.

I have personally found coming in dragging the plane along at 2000rpm does not work for me and have gone to almost flying a normal approach path.

Has your instructor not offered you any tips on correcting this?

[Bede]

Most of you are making this far to complicated than it has to be. Keep in mind, you won't ever land in a field shorter than the take off distance, so while trying to land on the back side of the power curve will win you points during your Alaskan super cub landing competitions, it won't do you much good on a flight test or even in the back country.

First off, when doing a short field landing pick three points: flare point, touchdown point, go around point.

Some introductory practice:
1) Go out on a zero wind day. On approach, aim for the beginning of the runway with full flaps and at the speed given in the POH. (For this exercise the beginning of the runway is your flare point) In the flare, power off and hold for as long as you can. When you touch down, figure out how far down the runway you touched down.

2) Do the same thing on a day with 10 knots of wind and 20 knots if you want to.

Practice:
3) Now, go out and practice your short field landings. With your knowledge of how far the aircraft floats, select a flare point that is far enough back to let you touch down at your touchdown point (keep in mind the wind).

4) I will guarantee you that if you select a decent flare point (keep in mind changes in wind and aircraft weight), and are on speed, you will touchdown well within your 100' tolerance. If you want you can put a 50' fudge factor in and allow the aircraft to touchdown a little faster. This way, you can save the embarrassment of touching down prior to your touch down point if all your speed bleeds off.

Mountain Flying Bible by Sparky Imeson is an excellent read.

[hairdo]

This way, you can save the embarrassment of touching down prior to your touch down point if all your speed bleeds off.

All sounds like good advice Bede, but it always confuses me when people land short of their touchdown point on a short field landing. Unless you are engine out, you should never land short of your intended landing point. If you are short in the speed and distance department, why not just add a bit of power to keep the aircraft off the ground for a few more seconds (or less)?

[Bede]

That is true, but I have got students from other instructors were flare, power off, power way on, power off, bounce, bounce.

If you plan the approach right, you shouldn't have to add power. Better to add power than to land short though.

[niwre]

aim point
aim point
aim point

If you don't set yourself up with a proper aim point (sticking too it and all other things considered) no matter where you decide to land, no matter the "float" (adjust for it then) you are setting yourself up for failure. Get your landing configuration set as early as practical or it will cause some undo "busy work" on short short final and can cause things like that bounce because one was busy with flaps or power and not with your aim point, round-out...

Using the 1000s is not my cup of tea as one does not practice maximizing the use of the runway. We can play what ifs and bad day at the office games but learning to maximize the runway length will give a student greater confidence in their abilities when confronted with an actual short runway. Not learning to can lead to poor habits.

Try to give yourself some parameters if all you have is 6000'+ (or whatever) runways to choose from. Try to pretend its a 2500' runway or something similar and base your aim points off that. If practical go to another airport where there is a short runway where you need to follow a proper procedure. If you and or your instructor can create a realistic scenario as possible it will lead to greater confidence.

[niss]

What do people here consider to be a short field for a C172 or a PA28140?

[trampbike]

530 ft ground roll at sea level, 20 degrees celcius and 2300 lbs for a c172.

640 ft (same conditions) on a Piper!

Well, that's not my opinion, they're the POHs opinions!

[niwre]

that may be so

but then add 1000 feet cause of aiming for the 1000' marker practice and add 200' cause people say they can't get the plane to stop floating