Training tips and tricks?

[Fearless Tower]

Why would that be your "only choice"? And with most GA small airplanes you're only about 10 knots difference between landing flaps and flaps up. 10 knots additional speed on a 2500-3000 pound airframe is not that significant. Even flaps up on most turbo props is not that big of an event.

Plus you still have reverse thrust available. You'll eat up a little more runway, but not that much.

Of note, the Dash 8 guy was very calm and not freaking about it. He simply declared an emergency to get the priority that comes with that. He declined the equipment. I probably should have been more clear when I mentioned that in response to the comment that declaring an emergency = rolling the equipment.

 

[poadeleted20]

Whatever blows your skirt, but my definition of an emergency means I'm asking them to roll the equipment.

Newer light plane POH's like the Cirrus family now have a third category of Abnormal Procedures besides Normal and Emergency Procedures. They categorize a flap failure as Abnormal, rather than Emergency, and I like that categorization.

However, the Part 61 regs and the PTS haven't moved that far, and don't discuss the concept of Abnormal vs Emergency procedures, so for those purposes, I put anything that isn't "Normal" in the "Emergency" category, and I think Flight Standards will agree with me. In any event, "flap malfunction" is specifically listed under "Emergency Operations" in the PP PTS, so as it regards instructors endorsing Student Pilots for solo and the practical test, failing to train for no-flap landings in flap-equipped airplanes is a violation of the regulations listed regardless of whether you would declare an "emergency" or not.

 

[flyingmoose]

Back to the original question:

I taught many of my private students spins and at a minimum I would make them demonstrate a falling leaf (holding it into the stall with full back stick and keeping it upright with rudder).

Thanks Brent! I like doing that one also.

 

[RotorAndWing]

However, the Part 61 regs and the PTS haven't moved that far, and don't discuss the concept of Abnormal vs Emergency procedures, so for those purposes, I put anything that isn't "Normal" in the "Emergency" category, and I think Flight Standards will agree with me.

I think not. Flight Standards doesn't rule out using common sense.

 

[poadeleted20]

I think not. Flight Standards doesn't rule out using common sense.

As regards declaring an emergency, I agree, but please remember the context of this discussion -- a Private Pilot who was never trained on no-flap operations before solo or before PP practical test, and the regulations regarding those activities (61.87 and 61.107), not the issue of whether you declare an emergency for a no-flap approach resulting from a flap malfunction. I'm quite certain Flight Standards would consider it a regulatory violation, not "common sense," for an instructor not to train Student Pilots flying flap-equipped airplanes on no-flap approaches/landings before endorsing that Student for solo or the PP practical test simply because the regulations only require training in normal and emergency procedures, not "abnormal" procedures. In fact, I think they'd consider the instructor involved to be bloody stupid, but that's just my personal opinion.

 

[dell30rb]

Hey Ren - spin would work, but I would just hold the stick on the aft stop and keep the rudder neutral and power at idle. It'll bob a little, won't spin,

I've tried that, it definitely bobs gently in/out of what i'd call an incipient and full stall. Never taken my feet off the rudder though, i'd still be worried about a spiral dive developing without some sort of way to see bank/heading changes. On the other hand I can see it doing a 'falling leaf' on its own.

Definitely won't spin, takes effort to get one going!

 

[numl0ck]

Nate, that's a great list. As a new pilot, it gives me some ideas to go improve and expand my flying (in no rush or doing anything unsafe of course).

 

[wabower]

And I'd be willing to bet whatever you want that I could convince them in less than 10 minutes that a no-flap landing contains absolutely no element of emergency, that that the PTS definition of malfunction assumes they work incorrectly (asymmetric deployment or such) rather than the pilot simply electing to land without using them.

In some cases no-flap landings are taught as SOP, even when the planes are so equipped. What should I tell the school at Northwest Regional that teaches no-flap as SOP in their 172 trainers?

Newer light plane POH's like the Cirrus family now have a third category of Abnormal Procedures besides Normal and Emergency Procedures. They categorize a flap failure as Abnormal, rather than Emergency, and I like that categorization.

However, the Part 61 regs and the PTS haven't moved that far, and don't discuss the concept of Abnormal vs Emergency procedures, so for those purposes, I put anything that isn't "Normal" in the "Emergency" category, and I think Flight Standards will agree with me. In any event, "flap malfunction" is specifically listed under "Emergency Operations" in the PP PTS, so as it regards instructors endorsing Student Pilots for solo and the practical test, failing to train for no-flap landings in flap-equipped airplanes is a violation of the regulations listed regardless of whether you would declare an "emergency" or not.

 

[poadeleted20]

And I'd be willing to bet whatever you want that I could convince them in less than 10 minutes that a no-flap landing contains absolutely no element of emergency, that that the PTS definition of malfunction assumes they work incorrectly (asymmetric deployment or such) rather than the pilot simply electing to land without using them.

I'll take that bet. You sign someone off for solo in, say, a Cessna 150, and endorse them for the practical test in the same type without ever having given them any training in no-flap approaches and landings, and then let me point that out to your supervising FSDO. I'll bet $1000 against your CFI ticket you get in trouble.

 

[wabower]

Then how do you explain the schools who take the opposite approach and don't use flaps for anything until well after solo? Is every landing an emergency?

I'll take that bet. You sign someone off for solo in, say, a Cessna 150, and endorse them for the practical test in the same type without ever having given them any training in no-flap approaches and landings, and then let me point that out to your supervising FSDO. I'll bet $1000 against your CFI ticket you get in trouble.

 

[Matthew]

Off the flap/no-flap topic:

Two memorable lessons during PP training:

1) similar to the 'lost' scenario that Jesse uses - night, hood, unusual attitude recoveries, partial panel. Then CFI uncovers the instruments and says, "Keep the hood on and using whatever you have available in the airplane, figure out where we are, find the nearest airport and take us there. When you think you are at the airport I'll let you turn on the airport lights and take off the hood so you can see how well you did." I fumbled around for a while, triangulated two VORs to figure out where we were, then tracked a radial until we crossed another radial, and turned on the airport lights. CFI let me take off the hood and the airport was nowhere in sight. Then I looked straight down and it was directly underneath. That was a really good feeling.

2) Night IMC work rather than simulated hood time. We took of into low overcast, stayed in the clouds, flew to a couple of VORs and did an instrument approach back home. My CFI/CFII handled all the clearances and approach procedures, but I flew the plane. Popping out of the clouds and seeing the strobes and runway lined up perfectly was way cool. That was the first time I'd ever seen that, and I thought it was really good to see the whole system in action.

--

One memorable lesson during a flight review:

Flew with a CFI who also flies aerobatics. We did a lot of steep turns and ground reference maneuvers but he really stressed looking at the wingtips for clues to how the plane is flying. You can learn a lot about coordinated turns and bank and pitch angles if you just pay attention to the wingtips. It was a trick that I hadn't learned from anyone else until he mentioned it.

 

[MAKG1]

GA we are used to having thousands of feet of extra runway. And no concerns fir our landing gear if we land at 60 kts instead of 45

Not always. Some of us use 2000 foot runways on occasion. You can do a no-flap landing on that (fairly comfortably if you've actually done it before), but not if you're going to approach stupid-hot.

If you touch down at 60, you're not flaring. That's the approach speed for a 172/152/PA28, and you'll hit nosegear first and probably bounce. Nosegears were NOT intended to take that kind of abuse, and they can and will break.

Read your POH. Flaps make a whopping 5 knot difference in the stall speed for a 172N, from clean to 40 deg. If you speed up beyond that, you're screwing up.

 

[flyingmoose]

Maybe a "stuff I only did well after I had my ticket" list is in order...

Thanks Nate, good list.

 

[flyingmoose]

If you touch down at 60, you're not flaring. That's the approach speed for a 172/152/PA28, and you'll hit nosegear first and probably bounce. Nosegears were NOT intended to take that kind of abuse, and they can and will break.

SO you cant flare at those speeds in those aircraft? No argument that you shouldn't land on the nose gear, but that is a common approach speed.

Read your POH. Flaps make a whopping 5 knot difference in the stall speed for a 172N, from clean to 40 deg. If you speed up beyond that, you're screwing up.

I did read the N model POH and it says Flaps down its 44 and flaps up its 50. So what?
1.3X 44= 57.2 Knots
1.3X 50= 65 Knots
That sounds a lot like what he said.

If I had to guess his statement was meant to show that the difference in the approach speed does not make that much difference. But that is just what I got from it.

 

[MAKG1]

SO you cant flare at those speeds in those aircraft? No argument that you shouldn't land on the nose gear, but that is a common approach speed.

You touch down AFTER flare. The comment was on touchdown speed, not approach speed, and compared it to 44 knots (the stall speed, not the approach speed).

If you touch down at 60, you will be nose down.

 

[JHW]

As I've accompanied new pilots on shopping trips for their first plane, the thing that impresses me is that they know how to fly the airplane but not how to do anything else.

How to work a gas pump
How to pick a harmless place to do a run-up
Which way to park
Picking a calm wind runway to minimize taxi length.
How can we keep this engine warm while we go to town?
Plugs are fouled what can we try?
Should we consider going VFR over-the-top in that direction, why or why not?
We need to deviate around this air mass storm, which side should we take?

I've flown with a lot of newbies who remind me of my kid, she'll tell people "I can fly fine, I just need dad to start the engines". I expect that from a 9-year old. OTOH I think an adult who just wrote a multi-thousand $$ check for an education, probably didn't get their money's worth.

 

[dell30rb]

You touch down AFTER flare. The comment was on touchdown speed, not approach speed, and compared it to 44 knots (the stall speed, not the approach speed).

If you touch down at 60, you will be nose down.

I was giving a 15 knot difference as a possible scenario. Didn't specify an aircraft.. GA aircraft can mean almost anything.

The point was - that many of the transport category aircraft are usually heavy with passengers/cargo, and flaps on some of those airplanes really transform the wing. And make a huge difference in landing speed.

And sure I know there exceptions for folks who might be flying a fully loaded baron into a 2000 foot runway or what not. Just generalizing..

 

[dell30rb]

How to work a gas pump
How to pick a harmless place to do a run-up
Which way to park
Picking a calm wind runway to minimize taxi length.
How can we keep this engine warm while we go to town?
Plugs are fouled what can we try?
Should we consider going VFR over-the-top in that direction, why or why not?
We need to deviate around this air mass storm, which side should we take?

That's a good list. One of the more confusing things after I got my PPL was figuring out 'where to park'. There is a sort of etiquette that is not taught but is picked up on after you visit enough airports.

 

[poadeleted20]

Then how do you explain the schools who take the opposite approach and don't use flaps for anything until well after solo? Is every landing an emergency?

I can't explain why they do that, and wouldn't even begin to try. But based on everything in the AFH, PTS, and POH for every certified production airplane I know with flaps, a no-flap approach and landing is an abnormal procedure.

And my bet still stands -- $1000 against your CFI ticket if you endorse someone for solo and the PP practical test in a flap-equipped airplane without ever giving them training and confirming their proficiency on a no-flap approach and landing and the FSDO is told of that and you don't get in trouble.

 

[Dave Krall CFII]

Why would that be your "only choice"? And with most GA small airplanes you're only about 10 knots difference between landing flaps and flaps up. 10 knots additional speed on a 2500-3000 pound airframe is not that significant. Even flaps up on most turbo props is not that big of an event.

Because your only other choices are trees, mountain sides, granite creek beds, etc.... And even then.

Don't fly in the mountains much?

Also, what if your only engine out landing site is a beach? I've seen a C182 flipped and totaled and a 150 wrecked because of improper soft field landing techniques calling for full flaps that weren't used in scheduled landings.

 

[denverpilot]

I'll throw another one on the list...

Going to a city you've never been to before, that has multiple airports... Which one to pick was a wonderment at first. AF/D helps, but places like PoA in the modern day are better.

Back then you guessed and then looked around to see how rusty the fuel pump was. Haha.

 

[wabower]

That wasn't my proposition to start with, it was that I could get them to agree that a no flap isn't an emergency, and that bet stands. But on the other one I'll make you a better deal. If you ever catch me signing off a primary student for anything you can have the ticket, big watch (if you'll promise to wear it) and entire Kirshner library.

I can't explain why they do that, and wouldn't even begin to try. But based on everything in the AFH, PTS, and POH for every certified production airplane I know with flaps, a no-flap approach and landing is an abnormal procedure.

And my bet still stands -- $1000 against your CFI ticket if you endorse someone for solo and the PP practical test in a flap-equipped airplane without ever giving them training and confirming their proficiency on a no-flap approach and landing and the FSDO is told of that and you don't get in trouble.

 

[gkainz]

find a couple of airports on the chart that you haven't been to ... maybe one LARGE and one very small .... maybe one with a restaurant on-field for a debrief over coffee

 

[poadeleted20]

That wasn't my proposition to start with, it was that I could get them to agree that a no flap isn't an emergency,

I never said otherwise. What I said is that signing off a trainee for solo/PP practical test in a flapped airplane without doing no-flap approaches and landings was a violation of 61.87 and 61.107, and I'll stand by that.

 

[RotorAndWing]

Because your only other choices are trees, mountain sides, granite creek beds, etc.... And even then.

Don't fly in the mountains much?

So you are now telling us it's impossible to land a small GA airplane on a short/soft field without flaps?? What did those GA airplanes do for years that didn't have flaps installed??

Better yet, if you are flying on to a "mountain" strip in your C-150 and the flaps fail, you now have an emergency? Who do you declare this emergency too? And you are there without any options??? Are you planning a no option flight into a strip where it's so short that a couple of knot speed difference on approach will either be successful or a crash? Really?

Also, what if your only engine out landing site is a beach? I've seen a C182 flipped and totaled and a 150 wrecked because of improper soft field landing techniques calling for full flaps that weren't used in scheduled landings.

And I've investigated accidents where the airplane was destroyed but yet was in fine working condition right up to the accident. In a C-172 as pointed out earlier there is less than a 10 knot difference between full flap and zero flap. Are you still trying to contend that that much speed difference is that critical? If so it falls under "pilot error".

 

[MAKG1]

I've seen a C182 flipped and totaled and a 150 wrecked because of improper soft field landing techniques calling for full flaps that weren't used in scheduled landings.

What IS the correct soft field landing technique for a C182?

It's not in the POH. Neither is a soft field takeoff. Short fields call for full flaps on landing, 20 deg on takeoff.

I prefer to do all my landings with full flaps, unless there is some reason not to (including practicing reduced flap landings). But soft field landings like that don't seem to be very soft, even with some power in.

 

[jpower]

I would definitely have liked to do some more real(ish) go/no go decisions (or when to make a precautionary landing decisions). For example, your voltage is starting to read a few tenths of a volt low. What do you do? At what voltage do you finally decide to land? That sort of thing.

And now for a mini hijack:

Yeah, kind'a like the the fighter pilot who called for landing priority because his single-engine jet fighter was running "a bit peaked." ATC told the fighter jock that he was number two behind a B-52 that had one engine shut down. "Ahhhh," the fighter pilot remarked, "The dreaded seven-engine approach."

I've seen this quote several times...but what in the world is an engine that is running "a bit peaked?"

 

[Dave Krall CFII]

So you are now telling us it's impossible to land a small GA airplane on a short/soft field without flaps?? What did those GA airplanes do for years that didn't have flaps installed??

Better yet, if you are flying on to a "mountain" strip in your C-150 and the flaps fail, you now have an emergency? Who do you declare this emergency too? And you are there without any options??? Are you planning a no option flight into a strip where it's so short that a couple of knot speed difference on approach will either be successful or a crash? Really?




And I've investigated accidents where the airplane was destroyed but yet was in fine working condition right up to the accident. In a C-172 as pointed out earlier there is less than a 10 knot difference between full flap and zero flap. Are you still trying to contend that that much speed difference is that critical? If so it falls under "pilot error".

Let's add rough water landings in seaplanes to the list!

Yes, the speed difference of full flaps makes a difference on landing on rough waves that hit the floats like wet concrete, AND can easily make the difference on getting off the water at all for takeoff. Next thing, aircraft could be washed onto rocks in frigid water. Yes again, can definately be an emergency to not have flaps.

On short strips, ESPECIALLY at high DA, flap operation can be a big deal breaker in safe landings. Say a pilot is headed for a backcountry destination that has plenty of runway length for an aircraft's full gross load, but suddenly MUST land at a very short strip enroute.

And no, no matter how well a slip is executed it won't do nearly as much as full flaps, that's why the old guys that slipped aircraft all the time invented flaps, to be going slower on actual touch down.

As far as declaring an emergency, that's a laugh in places where no one can hear your transmission. Yeah, of course you can land with no flaps and overshoot the end at even ten knots and shear your nose wheel off, then see if an emergency becomes "correct" term.

On a long, paved runway which it sounds like you frequent, not a problem obviously, where one can get away with all kinds of things because the length offers so much time to land. It's a matter of degree.

 

[NineThreeKilo]

(aside from all the PTS stuff)

Pre-Solo
Take offs and landings:
headwind, x-wind, tailwind, quartering tailwind
Flaps (if equipped) and no flaps, slips with flaps and no flaps,
Power off with and with out flaps.
Engine failure on t/o roll
Falling lead stalls (especially for folks flying non-spin friendly aircraft)


Pre-Test PPL
VMC to REAL IMC (done safe and legal)

Lost procedures, getting flight following without knowing the freq, having a sectional, AFD, etc (calling 122.0 with aprox location and asking for the freq)

Short and soft field (real short and soft field conditions), all configurations and power settings, 50/70 go-no go point, proper flap utilization.

Off-Field survey, length and go/no-go decision via over flight

spiral to land at night

Fuel Ops, Proper runup, direction and methods (foul plugs, mag issues, etc), rolling shutdown, tie downs with the correct knots, airing up tires.

Energy management, (hook turns, etc)

Cleaning a windshield and aircraft

Max Gross ops

When to pull flaps, when to dump flaps.

Probably forgetting a few

 

[RotorAndWing]

Let's add rough water landings in seaplanes to the list!

Yes, the speed difference of full flaps makes a difference on landing on rough waves that hit the floats like wet concrete, AND can easily make the difference on getting off the water at all for takeoff. Next thing, aircraft could be washed onto rocks in frigid water. Yes again, can definately be an emergency to not have flaps.

On short strips, ESPECIALLY at high DA, flap operation can be a big deal breaker in safe landings. Say a pilot is headed for a backcountry destination that has plenty of runway length for an aircraft's full gross load, but suddenly MUST land at a very short strip enroute.

And no, no matter how well a slip is executed it won't do nearly as much as full flaps, that's why the old guys that slipped aircraft all the time invented flaps, to be going slower on actual touch down.

On a long, paved runway, not a problem obviously, where one can get away with all kinds of things because the length offers so much time to land. It's a matter of degree.

You're really stretching this trying to justify your answer as to why you feel that a lack of operating flaps constitutes an emergency.

Flaps on most light GA airplanes don't make much difference, sorry that's a fact. It's all about energy management. The flaps only play a small part.

 

[Dave Krall CFII]

You're really stretching this trying to justify your answer as to why you feel that a lack of operating flaps constitutes an emergency.

Flaps on most light GA airplanes don't make much difference, sorry that's a fact. It's all about energy management. The flaps only play a small part.

Can you amplify your view on the specific examples above, instead of a glittering generalization?

 

[RotorAndWing]

Can you amplify your view on the specific examples above, instead of a glittering generalization?

I've stated my view quite clearly which is simple: In most GA airplanes flaps is a very small part of the equation on computing landing distance. In most light Single engine planes there is maybe a 10 knot spread between full flap and flap up and given the light airframe (2000-3000 pounds) the landing distance is negligible.

As for the other part, flap problems would be considered abnormal procedure, not emergency. Flaps don't go down, use alternate procedure, land. Very simple.

You're taking a simple problem and attempting to compound it in order to make a point (an inane one at that). In your example if you are taking a C-172 to a remote strip and the strip is only long enough to get the plane in with full flaps and not a foot more, and you haven't given yourself a contingency option in the event of a problem that's just poor planning on your part, not an "emergency" situation.

Back to flaps. In the large Transport aircraft I've flown the flap problems were considered abnormal, not emergency items. Even some others have chimed in on business turbo props and jets having similar procedures. So why would we consider a flap problem as an "emergency" in a SEL (or MEL) airplane when considering the operational factors?

 

[Dave Krall CFII]

Somewhere along the training path I like to demonstrate the "trapped on top of a layer with total gyro and electrical failure" scenario. I know it's a trumped-up deal but helps demonstrate aircraft performance and behavior characteristics that the student may not have seen before.

At altitude, tell the student to maintain S heading on the compass, power to idle, full flaps, full aft trim. Then tell him to cross his arms on his chest and control direction with rudder input only. Plane will slow to slightly over VSO and descend nicely with minor bobbing oscillations that may briefly activate the horn. Student's confidence and understanding in the maneuver, and the simplicity involved in achieving it, are usually "wow, I had no idea it would do that."

For simulated IMC demo or more realistic failure, use the same drill with foggles or hood on the student and a bath towel thrown over the panel.

Excellent excercise. Which aircraft won't it work in?

 

[Dave Krall CFII]

What constitutes an emergency is at the discretion of the PIC and nobody else. If your cahones are big enough that a flap failure only constitutes an abnormal procedure, then more power to you. If someone else chooses to be cautious and consider any abnormal procedure as the first step in an accident chain that demands to be broken, then I say more power to them.

Looking at flap incidents, I found this one interesting...not your average failure to deploy... http://www.thomaspturner.net/split flaps Musketeer.htm

Excellent write-up. I've always wondered just how bad it might be if only one flap was down. Worse than I thought....

Pilot experience is a big factor in the reality of the severity an "emergency" v. the semantics game.

 

[poadeleted20]

In most light Single engine planes there is maybe a 10 knot spread between full flap and flap up and given the light airframe (2000-3000 pounds) the landing distance is negligible.

If you consider a 40% increase "negligible," I'm with you. If not, you might want to recompute your data. Nevertheless, I agree that flaps locked up constitutes an "abnormal," not "emergency" situation, although I still think the FAA would say that training in that "abnormal" situation is required by 61.87(d)(11) (at least as an "equipment malfunction" if not as an "emergency procedure") before solo and by 61.107(b)(1) before the practical test.

 

[wabower]

My experience is limited to the normal trainers up through 182's on warm days. Can't ever remember trying anything bigger.

Excellent excercise. Which aircraft won't it work in?

 

[NineThreeKilo]

If you consider a 40% increase "negligible," I'm with you. If not, you might want to recompute your data. Nevertheless, I agree that flaps locked up constitutes an "abnormal," not "emergency" situation, although I still think the FAA would say that training in that "abnormal" situation is required by 61.87(d)(11) (at least as an "equipment malfunction" if not as an "emergency procedure") before solo and by 61.107(b)(1) before the practical test.

40%, what the heck are you flying?

Having a flap failure (not a asym. flap, those get a little hairy if your not quick) is not a emergency, aint that big of a deal, most of the planes I did training in (and the plane I learned to fly in) didnt even have flaps!

In a 172/152/PA28/Grumman/Mooney/etc it aint that big of a deal.

I train 0 flaps and full flaps, but it normally only takes the average student a one or two t&gs to figure out 0 flap, not rocket science.

This why you are sposed to teach slips, 0 flaps with a slip really aint a issue.

I would not speak poorly of a CFI who didnt do 0 flaps before solo, I'd just call that average for a low time or old weekend warrior CFI.

 

[poadeleted20]

40%, what the heck are you flying?

A plane whose landing approach speed is about 10 knots faster without flaps than with. Do the math -- about 40% more energy to lose on touchdown, and a flatter approach path which extends the obstacle clearance distance. Landing distance in a typical flap-equipped light single is extended about 40% -- really.

I would not speak poorly of a CFI who didnt do 0 flaps before solo, I'd just call that average for a low time or old weekend warrior CFI.

I speak poorly of any CFI who fails to do the regulatory minimum before sending a trainee solo. I'm sure we've all heard the line about "if the min wasn't good enough, it wouldn't be the min," but if less than the min was good enough, the min would be lower, and the regulatory minimum for solo includes flapless landings. If you doubt me, I'll happily make the same bet with you that Wayne declined to accept.

 

[RotorAndWing]

A plane whose landing approach speed is about 10 knots faster without flaps than with. Do the math -- about 40% more energy to lose on touchdown, and a flatter approach path which extends the obstacle clearance distance. Landing distance in a typical flap-equipped light single is extended about 40% -- really.

OK, let's look at book numbers. In a C-172S at sea level on a 20C day, zero wind, ground roll is 585 feet with flaps at 30. At zero flaps that is increased to 789 feet. Somehow I don't think the average GA pilot is operating into 1000 feet strips routinely with a C-172S, but if he is he is still achieving POH performance data.

Even clearing a 50 foot obstacle it will need 1350 feet at flaps 30 and 1822 feet at flaps zero.

So take an average airport of 3000 feet and a landing to clear a 50 foot obstacle in zero wind, no flaps and that leaves a stop margin of 1178 feet.

 

[poadeleted20]

OK, let's look at book numbers. In a C-172S at sea level on a 20C day, zero wind, ground roll is 585 feet with flaps at 30. At zero flaps that is increased to 789 feet.

So, about 35% -- I was pretty close.

Even clearing a 50 foot obstacle it will need 1350 feet at flaps 30 and 1822 feet at flaps zero.

Even closer to 40%.

Thanks for confirming what I said.