Adding Flaps in Ground Effect?

[-]

colin_do@reddit

It can be a useful technique if you misjudge and need to stretch your glide in a PO180, especially if you have johnson bar flaps and you can deploy the first notch quickly. I wouldn't make a habit of relying on it, better to stay a little high and fine tune your approach with a slip than to get in the habit of coming up short.

Reply

[-]

No-Grab-1946@reddit (OP)

For more context, I'm training in a Piper Arrow with the bar flaps, like you said. We are not allowed to slip in this airplane, so it's less flexible than a Skyhawk. Yeah, I agree with you on not making it a habit. This is just something I have as a backup to use when I mess up. (Which happens when I did not account for the tailwind and downwind). When I'm short, I'll pitch the nose down, trading all my altitude for airspeed, and get into ground effect and utilize flaps to float.

Reply

[-]

JohannLandier75@reddit

I took my commercial in the same aircraft. I was going to be short of my touchdown point by enough that I would have busted. I looked over at the DPE when I realized this thinking well damn this sucks and noticed she made an exaggerated point of looking at the handle for the bar flaps. ( My instructor had also mentioned this but said he wasn’t sure how the DPE would view it) so I used them to float to my spot and passed. She later said she expects commercial pilots to be able to demonstrate the ability to use all the tools at their disposal with an aircraft..

Reply

[-]

makgross@reddit

Arrows have no restrictions on slipping, even with flaps. For 172s, extended slips with flaps are “not recommended” (but some instructors will claim they are prohibited even though that was true only for really old straight tail 172s that you’re not likely to find). Frankly, Arrows are relatively easy on PO180s. They fly like bricks with the gear down. You won’t be 500 feet high over the numbers like every 172 driver does the first time.

Reply

[-]

keenly_disinterested@reddit

> For 172s, extended slips with flaps are “not recommended” (but some instructors will claim they are prohibited even though that was true only for really old straight tail 172s that you’re not likely to find). It's like any manufacturer/FAA recommendation: You can choose to ignore a recommendation, but if something bad happens you might have to explain why you chose to ignore it.

Reply

[-]

makgross@reddit

Or you could read what Cessna actually wrote about it in their POHs….

Reply

[-]

keenly_disinterested@reddit

Which version? The 1975 POH states: > Steep slips should be avoided with flap settings greater than 20 deg due to a slight tendency for the elevator to oscillate under certain combinations of airspeed, sideslip angle, and CG loadings. The 1976 POH doesn't contain a statement like that, it simply says there must be a placard near the flap switch that states: > Avoid slips with flaps extended. Either way, the manufacturer clearly says you shouldn't slip the plane with flaps extended. You can ignore that if you choose, but be prepared to explain why you ignored it if something bad happens.

Reply

[-]

org000h@reddit

"Avoid" is a very different word to no "No", "Not allowed", "Not permitted" or "Not approved".

Reply

[-]

keenly_disinterested@reddit

Nowhere did I suggest the POH prohibits slips with flaps. Here's the question though: If your POH says you should avoid slipping the plane with flaps extended would you do it while getting a checkride? If not, why?

Reply

[-]

org000h@reddit

Uhh your literal comment: \> Either way, the manufacturer clearly says you \*shouldn't\* slip the plane with flaps extended. You can ignore that if you choose, but be prepared to explain why you ignored it if something bad happens. "Shouldn't" ... "should not" and "avoid" mean two different things. And yes, I did aggressively slip a C182 with full flaps on a simulated engine failure on my commercial flight test to make the runway. I also slipped an aerobat 150 with half flaps to make the field when i did my aerobatics instructor flight test for another engine out scenario. If the POH says no, it's a no. If the POH says avoid, it's a no unless you need it. That's my take, but you do you though.

Reply

[-]

keenly_disinterested@reddit

Yes, you described exceptions to the rule. We all know that recommendations, even prohibitions, go out the window in the event of emergency. That's clearly stated in the regs. That's not what I'm talking about and I think you know that. No one is going to question if ignore a recommendation in an emergency. > you do you though. Thank you. You too.

Reply

[-]

Select_Respond_8627@reddit

The only people who would really care is the insurance company if you bend the plane and that would just to assign percentage of responsibility. In the event that an incident is related to slipping the plane, odds are pretty good the pilot is going to be responsible regardless of manufacturer recommendations.

Reply

[-]

TheSkyFlier@reddit

They just say to avoid slips with full flaps because it can cause buffeting. I’ve slipped 172s with flaps plenty of time on the stipulation that if I experience buffeting I pull the slip out. I’ve never experienced buffeting.

Reply

[-]

keenly_disinterested@reddit

Not all C172 manuals say what you claim. Some don't make any comments about why, they simply say you should avoid slips with flaps extended. Again, you can ignore the POH if you like, just be aware that you might have to explain why. BTW, because you've done something the manufacturer says you shouldn't without getting into trouble in the past is not a good reason to keep doing it. Look up "normalization of deviance space shuttle." I'm not suggesting slipping a C172 with flaps will result in catastrophe, I'm commenting on your justification for doing so against manufacturer recommendation.

Reply

[-]

TheSkyFlier@reddit

I totally agree, read the POH. I read the POH for the planes I flew and followed it. Of course if it’s prohibited, it’s prohibited. People getting advice on how to fly their planes from randos on the internet is definitely bad practice. I’ve flown with a genuinely concerning number of pilots who don’t follow a single word of what’s in their POH. I ask them for Vy and they say “I dunno point it up.”

Reply

[-]

eSUP80@reddit

Me neither, done it many times with our 74 C172. If you did…. Nose down, less slip 🤷‍♂️

Reply

[-]

wapkaplit@reddit

Keep it in your back pocket as a tool for when you really need it (and by that I mean an emergency). For normal ops you should be flying a stable approach and going around if you're short. If you've lost the engine, you're gliding in, and you realise you're just a tiny bit short, as an absolute last ditch effort you can drive the nose down assertively, pick up some speed, level off and go straight to full flaps, using the float to balloon up a little bit and hopefully make it to the runway. It's a final resort.

Reply

[-]

aftcg@reddit

Slip the dammed airplane. Something is wrong at your school if they won't let you slip a Cherokee.

Reply

[-]

SaratogaFlyer@reddit

Agreed, this is some grade A malarky!

Reply

[-]

R5Jockey@reddit

What?? You can’t slip your Arrow? The ACS specifically mentions slips in the skills section (S7) for the power off 180.

Reply

[-]

Icy-Bar-9712@reddit

Shit, its a PPL maneuver. Slip to land, touchdown point +400 on the standard.

Reply

[-]

No-Grab-1946@reddit (OP)

We slip a whole lot in our 172, just not in the Arrow. Honestly, I don't know why; I should ask my CFI next time. I've only flown the Arrow for the final stage of Commercial training; the rest was in a 172.

Reply

[-]

No-Grab-1946@reddit (OP)

Honestly, now that I think about it, I really don't know why. I went back to our SOP and also the Arrow POH, and there are no restrictions on slipping. Students in our school, including me, are very proficient in slipping to land because most of our training, from pre-solo leading up to the last stages of Commercial, is in 172s. Now, I honestly can't find any literature that prohibits slipping our Arrow. It's just something that the instructors don't demonstrate, and the students collectively don't do. It sounds stupid, I know.

Reply

[-]

colin_do@reddit

Is that a flight school policy? What a handicap.

Reply

[-]

Swvfd626@reddit

100% is, I did my complex in the arrow 3 & 4 and we're we're specifically thought to do a slip to land.

Reply

[-]

EpicRedhead13@reddit

Is that a POH thing or a school thing? I leaned forward slips as part of my PPL in an Arrow II.

Reply

[-]

Aggressive_Lime2214@reddit

Some of these advanced flying techniques need to be reserved for those you know good and damn well what they’re doing, and gatekept from low time pilots until they have a deep and thorough understanding of aerodynamics and flight science. They can get themselves into a lot of trouble with these if they don’t know what they’re doing.

Reply

[-]

exadeuce@reddit

You're destabilizing yourself during a critical phase and you don't want to do that. Unless you're extending your glide a few feet to pass over lava, I can't imagine a scenario in which the risk is worth it. You can put the wheels on the grass in front of the runway, it's fine.

Reply

[-]

No-Grab-1946@reddit (OP)

Not lava, but I'm extending a few feet to pass the checkride :)

Reply

[-]

exadeuce@reddit

You know what's worse than failing a checkride? Damaging an aircraft during a checkride and failing anyway.

Reply

[-]

Oogaboogacoo@reddit

If you damage an aircraft by adding a notch of flaps in ground effect, especially in the arrow, you’ve got some other issue with control of the aircraft.

Reply

[-]

exadeuce@reddit

Oh well I guess we should just throw out all that stuff they teach us about stabilized approaches. Just control the plane correctly and you will never damage a plane ever. Why didn't the FAA think of that!?

Reply

[-]

Oogaboogacoo@reddit

No, but in no way is that destabilizing your approach When you’re already in ground effect. And there is no greater risk with doing so than landing in the grass and running over runway lights like you suggest

Reply

[-]

exadeuce@reddit

Part of the criteria for stabilized approach is being in the correct landing configuration. The reasons for this are not trivial.

Reply

[-]

Oogaboogacoo@reddit

That criteria says same configuration when on final approach. So it would be unsafe to adjust flaps at all by the time you’ve turned final? You’re telling me the same technique that works in an arrow won’t work in a 737 which is not the aircraft your brand new commercial single engine pilot is flying? I would have never guessed and would think landing in the grass before the runway would be perfectly fine for that aircraft too

Reply

[-]

exadeuce@reddit

landing a Cessna in grass really is fine.

Reply

[-]

Oogaboogacoo@reddit

So that means the same thing works in the 737 right

Reply

[-]

exadeuce@reddit

You're getting dumber and dumber here. Bye forever.

Reply

[-]

Oogaboogacoo@reddit

Bro lost goodbye lol

Reply

[-]

No-Advertising-1402@reddit

Also works the other way around too if your speed isn’t too high, lol. Take flaps out when you’re floating long and catch the sink

Reply

[-]

ShittyLanding@reddit

You can also level off above ground effect, let the speed bleed off, and then set her down if you don’t want to monkey with the configuration.

Reply

[-]

No-Advertising-1402@reddit

Definitely a good way to handle it!

Reply

[-]

No-Grab-1946@reddit (OP)

Here's an interesting thing I just realized. Most of the instructors in my school are very against the practice of putting flaps up to stop the float but teach (or are neutral) on the practice of adding flaps to float.

Reply

[-]

No-Advertising-1402@reddit

Yeah because if you screw it up you slam the hell out of it haha. But it’s fun to try. I would never suggest doing it on a ride. I ended up needing it on my ride because I botched it a bit but my examiner and I agreed it was fine beforehand as long as I hit the point.

Reply

[-]

draggingmytail@reddit

Didn’t some guy just come in here a couple days ago and complain that he failed his checkride for “flap boosting” ?

Reply

[-]

rFlyingTower@reddit

This is a copy of the original post body for posterity: --- I'm coming up on my Commercial Practical, and throughout my training, I have always been nervous about my PO180. Fortunately, recently, learning has occurred, and I have been successful with this maneuver. One of the techniques I was taught by my CFI while practicing PO180 is to incrementally add flaps in ground effect to float further when needed. I know the general concept of this is that adding flaps equals more lift and more induced drag, but in ground effect, adding flaps equals more lift and not as much induced drag. So, to my understanding, it doesn't sound like a hazardous technique that I can keep in my arsenal when I mistakenly turn base too late. Now my question is, in the eyes of other pilots, CFIs, and DPEs, is this a "bad thing" that I shouldn't do? I'm asking this because I saw one of the posts on here of a pilot failing his Commercial Practical partly because of this practice. TL,DR: Is putting flaps in ground effect frowned upon, and if yes, why? And should I do it on my Commercial Practical? --- Please downvote this comment until it collapses. Questions about this comment? [Please see this wiki post before contacting the mods](https://www.reddit.com/r/flying/wiki/index/rflyingtower/). --- I am a bot, and this action was performed automatically. If you have any questions, please [contact the mods of this subreddit](https://www.reddit.com/message/compose?to=/r/flying).

Reply

[-]

Useful-Photograph744@reddit

The PO180 is an has always been a misunderstood maneuver. It is not an emergency maneuver but one that shows mastery of aircraft energy management. Adding flaps in ground effect is certainly a way to make your point in a pinch but I would not rely on this to pass your check ride. Whether or not you bust your ride for this is up to the DPE but I would always discourage my students from this in training. Before you go for your check ride make sure you can reliably make your point under various wind conditions without the use of flaps in ground effect. For practice I would even recommend you try to do this maneuver without changing configuration at all. Try them completely clean all the way to touchdown and do a few where you dump your flaps abeam your point. This can be a great way to really see how different flap settings affect your glide.

Reply

[-]

dudeman1018@reddit

\>Whether or not you bust your ride for this is up to the DPE Is it in the ACS or not?

Reply

[-]

dinnerisbreakfast@reddit

The real issue is that if you need to use flaps in ground effect to make the runway, then you are going to be well short of the threshold at a very low altitude. Many examiners would not risk the aircraft, their certificates, and possibly their lives on the assumption that you will be able to stretch the glide to the runway once you are in ground effect. I have actually had to use ground effect to stretch the glide to the first brick of the runway, and it was not something that you should ever be doing just for practice. If you're over the runway, sure, test the theory. But if you were on a checkride in a perfectly good airplane and you decided to take it that low, that far short of the runway, I would really have to question your decision making.

Reply

[-]

Useful-Photograph744@reddit

The ACS is vague on this topic which is why it is contentious. The applicant must demonstrate knowledge of a stabilized approach and energy management concepts. The applicant must demonstrate the skill follow a planned path to their selected touchdown point while correctly configuring the airplane. A DPE can argue that your need to use flaps in ground effect violated the knowledge of a stabilized approach and that you did not correctly follow a glide path to your landing point with the aircraft correctly configured. Commercial ACS CA.IV.M.K1 CA.IV.M.S3 CA.IV.M.S6

Reply

[-]

cobinotkobe@reddit

Interestingly the Power off 180 is the only landing task to not have the “stabilized” criteria in the skills section. It has it in the knowledge section (CA.IV.M.K1 as you cited) but not the skills section where it differs from the other landing tasks

Reply

[-]

colin_do@reddit

I love that. "I am aware that stabilized approaches exist; however, this maneuver will not be an example of such." Check and check.

Reply

[-]

No-Grab-1946@reddit (OP)

Thank you, I like the source cited

Reply

[-]

Shamrock132@reddit

That’s the fun part, it doesn’t matter! There’s examples on here of people failing because they added flaps, and examples of people saying adding flaps was the only reason they passed. It’s probably the most misunderstood maneuver by examiners, instructors and applicants.

Reply

[-]

saml01@reddit

Guy on here just failed a check ride doing that. Id take my chance on leniency then doing something obvious and signalling to the dpe you knew you were short.

Reply

[-]

ShaemusOdonnelly@reddit

Wtf. Ground effect becomes significant at an altitude of about half of the wing span. If you only start to stretch your glide at that point, that is way too late. You would have flown critical parts of the final approach at too low of an altitude. I can see why people have failed a checkride for this. Some input from a glider pilot: If you have a headwind, the actual best glide speed is higher, so increasing the approach speed can help to stretch the glide. The reverse is true for a tailwind.

Reply

[-]

org000h@reddit

This 100%! Recognise an unsuitable / unstable approach and correct it early ... if you're fixing stuff in the flare, you dun goofed a few miles ago. And absolutely - I'm sure in a few POH's I've seen different glide speeds for different weights and winds, and it's always been somewhat counter intuitive to what I initially thought it should be.

Reply

[-]

shanihb@reddit

I was taught by a DPE to not use flaps on a PO 180 until the runway was made. If I was a bit short, reach for the Johnson bar, verbalize “flaps identified and ready to be used”, and use them as necessary to float or dump them to hit a spot. As u/Purple-Surprise-8529 said, I would ask the DPE his opinion before any checkride.

Reply

[-]

Gh3rkinman@reddit

It is a valid technique in the right situations and with awareness of the hazards involved. Kind of like anything in aviation really.

Reply

[-]

PoemCritical@reddit

As a DPE, I just expect you to mange the energy correctly to land +200/-0 from your selected spot on centerline. However you make that happen, doesn't matter to me. That said, YMMV depending on the examiner.

Reply

[-]

MalTheCat@reddit

Here’s how I always taught it: Adding flaps in ground effect is a tool in your arsenal; only use it as a last resort to hit your point. If the DPE fails you for doing it, well, you were going to fail by missing your point anyways.

Reply

[-]

R5Jockey@reddit

This. Exactly this. If your option is to fail because you landed short or long or use flaps to nail your point…. Use flaps. There’s literally no downside at that point. So be prepared for either.

Reply

[-]

Temporary-Fix9578@reddit

I’d argue that adding flaps is safer than retracting in ground effect. I don’t really see them as equal

Reply

[-]

MalTheCat@reddit

I think that’s probably fair but it’s definitely possible if you’re still just a shade off the ground and still floating to take the flaps out and settle the plane down with less float. Again, DEFINITELY not the goal or recommended but the physics are there.

Reply

[-]

dendronee@reddit

My thought is…. If you’re pulling a rabbit out of a hat you should have gone around. This “technique” is a crutch for poor initial application and may lead to further poor performance. I applaud using all tools from the shed but please be careful. It may work one time and not the next.

Reply

[-]

R5Jockey@reddit

The whole point of the power off 180 is that you can’t go around. We’re not talking about normal landings here.

Reply

[-]

MEINSHNAKE@reddit

It’s a technique that you can use, but it isn’t something you want to rely on.

Reply

[-]

The_Big_Obe@reddit

I always taught people to plan to be a bit long. Better to make the field than not. Then after you are fully configured. I taught reducing speed and an early slip were your tools to control touch down. As others have said, if you are currently consistently needing a bandaid to make your points in the PO180. You probably still need more practice. A challenge with all my students was the let's see who can get closer to the point. Me or you. PVT and COMM students. I always went first. This way when I usually got the maneuver correct as a more senior CFI, the student had a chance to watch a more experienced pilot do the maneuver and I got a much needed currency landing. For the student, they got to see my planning and where I made my changes. Plus it was a fun challenge for both of us PS, it was so funny to most of my students when I messed it up and they won. It happens

Reply

[-]

No-Grab-1946@reddit (OP)

Taking notes for when I become a CFI :)

Reply

[-]

The_Big_Obe@reddit

Many ways to skin a cat. CFI'ing gets pretty boring after a while. You'll come up with games and things you find fun to keep it interesting.

Reply

[-]

RecentAmbition3081@reddit

You’re getting taught wrong. IMHO

Reply

[-]

fatmanyolo@reddit

I’ll share in your downvotes, it’s bad technique. I’d have only shown a student that as a last “Hail Mary” to throw at it if they were about to fuck it up.

Reply

[-]

storyinmemo@reddit

I taught this on my CFI ride with a Johnson Bar flaps handle. Flaps are a meaningful aerodynamic control. In a glider I am manipulating speed brakes for what amounts to a similar effect. This is very aircraft dependent. In jets you get auto deploying spoilers. With any back country plane or STOL competition, you'll see them hand on the flaps lever to dump the flaps.

Reply

[-]

Raccoon_Ratatouille@reddit

If the alternative is hitting something short of the runway you probably don’t have anything to lose, but plan a is to fly the PO180 right the first time

Reply

[-]

Puravida1904@reddit

I was always told you should be stabilized by 200ft AGL, so no forward slips or flaps below that…

Reply

[-]

Mountain-Captain-396@reddit

Sometimes you gotta slip er' in

Reply

[-]

Due-Letterhead6372@reddit

Some people frown on it, I don't. It is a useful technique, but be careful, that one guy who was a check airman at a 141 school will fail you for adjusting flaps below 200 AGL!

Reply

[-]

zkoolie@reddit

Guy sounds like a tool

Reply

[-]

Due-Letterhead6372@reddit

It was a reference to a post yesterday about this same topic where a guy said exactly that.

Reply

[-]

HexaJet@reddit

I’ve spent a year or two as a 141 cert check instructor, and I wouldn’t fail someone for that unless they were actively endangering the aircraft. Few DPE’s advice to me on the matter was “don’t scare me, and everything will be fine”

Reply

[-]

Purple-Surprise-8529@reddit

Ask what your examiner thinks when you schedule the ride well ahead of time. “I’ve heard different opinions, what does a perfect one look like to you?”

Reply

[-]

LawManActual@reddit

I’ve seen it, I don’t like it. There is no other time we teach to change configuration in ground effect, I’ve watched other peoples students a few times cause a tail strike trying to do it. I think it shows poor ADM, personally. It’s one of those controversial items that there isn’t a right answer to. Proceed with caution.

Reply

[-]

parking7@reddit

I think you answered your own question. Some DPEs will frown upon and it and some won’t. So you should tailor it whenever you should be doing this on the practical or not. From a practical perspective you should learn flap manipulation on final with the right CFI and know it’s not the end of the world to change config on final. I ended dumping the flaps (from 30 to 0) on my PO180 in my commercial checkride as I was about to float way past my point. DPE was fine with it.

Reply

[-]

bobnuthead@reddit

I don’t personally use it, or tell people not to, but I’ve heard multiple stories of DPEs being upset by it, not just online. Mileage varies.

Reply

[-]

shockadin1337@reddit

The DPEs i’ve met were fine with it. I did it on my commercial ride in my flying brick and my DPE gave me a high five lol

Reply

[-]

DingleBurg2021@reddit

I used it on my commercial. Worked great.

Reply

[-]

FlowerGeneral2576@reddit

I’d focus more on proficiency in executing the rest of the maneuver correctly, such as timing your base and final turn better, as opposed to planning on using this technique from the get-go.

Reply

Reply to Post

87 Comments