View Full Version : Cessna 172 landing techniques - what is the difference?


ifresh21
12th Feb 2011, 22:29
Hi guys,

I fly 172R and am a post (first) solo level student. I will ask my instructor next time I fly, but I want to hear what you guys think.

I learned to land my pulling the power when I am still pretty high on final, and gliding all the way down to the runway. I know that some instructors (I flew with one) teach that you keep power in all the way down to the runway, and then pull power just before the flare (basically).

What is the difference and pros/cons of each method? Any safety issues between the two? Which is more challenging?

Thanks a lot in advance.



Pilot DAR
12th Feb 2011, 23:55
In any case, in nearly all nosewheel planes, your objective for a normal landing will be to have the aircraft very nearly stalled just as you touch the runway, with good directional control, and a suitable length of runway ahead.

That said, you will be passing through the speed range (during the flare)from a suitable approach speed, to the stall speed of the aircraft for a nice touchdown. With skill, this can be neatly done power off, from however high you wish. If you're still developing that skill, you will find it easier to lengthen the time you have in the flare, to get everything just the way you want it to be for that nice landing.

With an extra long runway, it is actually possible to touch down with considerable power. Pundits will perhaps jump on me, suggesting this is pointless, but on a really cold day, when you don't want to shock cool an engine, it's appropriate to carry some power all the way in.

However, the opportunity to land with power is no excuse for not practicing the skill of a power off gliding landing.

There is no right or wrong way, as long as the end result is a neat, well controlled landing - but, if you're relying on power to carry you to the touchdown point, and it quits, you're going to look foolish if you don't make the runway - you should have been able to under normal circumstances....

AdamFrisch
13th Feb 2011, 00:33
I find that generally my landings are smoother if I fly the approach with a bit of power and only chop it in the flare. Unless it's a really tight field or a steep approach to clear obstacles.

RatherBeFlying
13th Feb 2011, 01:00
I had the good fortune of finding an instructor who liked to fail the engine after the downwind checks were completed. In the C-172 with 40 flaps available, it was pretty simple to keep the approach tight and select 40 flaps when the runway appeared almost straight down. With 40 flaps, you need a steep descent to keep the speed up and have enough energy to flare -- especially with an upslope on the runway.

So if you are carrying power on the approach, if the engine becomes unhappy, you might not make it to the runway. Removing flap can cost you considerable altitude.

In cold weather, I do carry a bit of power so that the engine will not cool too rapidly; also a warmer engine will be useful if a go-around has to be done.

SNS3Guppy
13th Feb 2011, 02:03
Idle descents to landing are good training, but generally poor practice.

Have a little more respect for your engine.

englishal
13th Feb 2011, 07:16
Since flying from smaller strips, I tend to drag the aeroplane in under power, so lots of drag and high angle of attack. The advantage is that you can more accurately determine your touchdown point, and can keep speed on the slow side of approch speed. You also minimize float, and maximize stopping distance.

Disadvantages include that if you engine stops on final, you won't make the runway (does this ever happen?).

This is not appropriate for all people though, the aeroplane I have flown most recently is designed for STOL operations and has leading edge slats, and at high AoA those slats pop out giving a nice stable approach and excellent short field.

Gertrude the Wombat
13th Feb 2011, 08:54
I learned to land my pulling the power when I am still pretty high on final, and gliding all the way down to the runway. I know that some instructors (I flew with one) teach that you keep power in all the way down to the runway, and then pull power just before the flare (basically).

Yes well, I use power as necessary to keep the approach path reasonable, and depending on all sorts of things (eg headwind and how competent I'm being that day) this might mean having the engine at idle at various points. One runway has a decided sink over the ponds in most weather conditions so what looks like a nice glide approach will almost always need some power as I cross the water.

Also if I follow the teaching "turn base, reduce power to 1500, remain level until below flap limiting speed, flaps 30, descend" I'm sometimes (again depending on wind etc) going to end up over the threshold at several hundred feet, so cutting the power to idle after the base leg turn to see how it goes today often works better for me particularly with a tailwind on base leg.

I've done these things with a variety of instructors sitting next to me on various lessons and check rides over the years and none has ever complained. Well, not about power handling on the approach, anyway.

BackPacker
13th Feb 2011, 10:25
As others have told you, there's something to say for both techniques and in the end we all use a blend of both. And practicing power-off landings is never a bad idea, as long as you have considerations for the engine (shock cooling) and the others in the circuit.

I think it's important not to focus on one or the other too much, but to understand some of the aerodynamics behind it.

First, what happens when you reduce the power to idle? Of course, thrust is reduced so you either maintain the pitch attitude and bleed off speed, or you have to lower the nose to keep the speed up. Trim plays a role here too. If the aircraft is trimmed correctly it will drop the nose by itself to maintain speed. But if the aircraft is not trimmed correctly you need to know exactly what control position/force is necessary to achieve the desired effect.

But that's not all. Due to propwash effects, p-factor and whatnot, reducing the power will induce yaw to the right (assuming the standard US Lycosaurus setup) which you need to counter with left rudder. For the exact same reasons that increasing the power, for instance at the startup roll, requires right rudder.

At your stage in training, do you find yourself intuitively controlling the rudder properly already so that the ball is centered? Or, in crosswind landings, can you keep the aircraft aligned with the runway intuitively while you play with the bank angle to induce a sideslip and maintain the centerline? Do you already know or feel the pitch attitude that's required to maintain speed with idle power, or to bleed off the correct amount of speed? If not, I can well imagine that your instructor is teaching you to land in stages, where you first reduce power to idle, have a second or so to consciously counter the yaw and pitch effects of this, and then start the flare.

And second, talking about the flare. This is not just a maneuver to bring up the nose so the nosewheel doesn't hit first. It's also a maneuver that's used to bleed off energy. After all, any movement of the controls, at any time, results in induced drag. But in the flare you are at the wrong end of the drag curve which multiplies this effect.

This is one of the two reasons we don't approach at stall speed. We need that extra energy for the flare. The steeper your approach is, the more energy you need. (The other reason is for protection against gusts.)

So again, your instructor will teach you to fly your final approach at a certain speed, and an approach angle that belongs to that speed. Eventually you should be able to fly to book (POH) numbers but initially your instructor may want you to fly a little faster than that. That gives you the ability to close the throttle a second or so before the flare, stabilize the aircraft again, maintain the pitch attitude so speed bleeds off, and still have enough energy left for the flare itself.

As you progress further, you'll fly the aircraft much more intuitively and you can combine all these actions. Heck, you could even extend the reasoning behind all this, and do something opposite if that's required. Pilot DAR has given you an example already: Leaving a bit of engine power on to prevent shock cooling. I'll give you another example. I was downwind 1000' in a fully loaded (4 adults) PA28 and needed to fly a tight circuit because of a 737 on final, which I had to get in front of (ATC orders). So I made a tight turn onto a tight final and approached the runway at a relatively high rate of descent. Instead of closing the throttle in the flare, I used a very small and short burst of power to cushion my ROD, and then made a very nice and controlled idle power touchdown. Without that burst of power I'm not sure if I would have gotten the energy to fully cushion the flare.

bose-x
13th Feb 2011, 10:54
As the owner of a 172 I tend to pretty much glide the last 100ft or so just using trickles of power to correct for any turbulence etc. So pretty much a blend between glide and power.

The 172 needs to be put down at the correct speed or it will just bounce back into the air or wheelbarrow and shimmy down the runway. Carrying power to touch down will inevitably find you to fast and thats when things go wrong.

By using a blend of glide and power you control the approach speed exactly and thus the touch down speed.

With an extra long runway, it is actually possible to touch down with considerable power. Pundits will perhaps jump on me, suggesting this is pointless, but on a really cold day, when you don't want to shock cool an engine, it's appropriate to carry some power all the way in.

I will respond to that. Maybe in the minus millions of Canada this could be a problem but the power requirements for a normal circuit have allowed the engine to cool down from cruise power and taking power off further for a glide approach is going to make little difference. Especially as the nature of a glide is no different from the taxi back to the ramp.

At the end of the day there are many ways to skin a cat. Look listen and learn and then use what is best for you. When you own your own aircraft you will use the technique that is not only safe and comfortable but also the kindest to your aircraft.

Pilot DAR
13th Feb 2011, 12:21
the power requirements for a normal circuit have allowed the engine to cool down from cruise power and taking power off further for a glide approach is going to make little difference. Especially as the nature of a glide is no different from the taxi back to the ramp.


On a warm summer day, agreed. Though, lets remind ourselves that the power to fly the "normal" circuit, could in many cases be about cruise power - which does not really afford the engine much opportunity to begin to gently cool down.

So, when it's minus millions out (well for my flying, I begin to think of things as getting cold at -25C), The nature of a glide is very much different to that of taxiing in as it affects engine cooling! The glide will be at let's say four to five times? the airspeed of taxiing? That's a lot of cooling in the glide, compared to the ground (depending upon how you taxi!). When the engine stops developing power, it stops developing most of it's heat. But if you're still flying, you're still cooling. Too much cooling all of a sudden is very bad for the cylinders.

On the 6000 foot runway, where I fly to work a few days a week, I amuse myself sometimes with partial power takeoffs, and high power landings, in the mighty C 150. With full power RPM being 2750, I have quite happly gotten airborne and "climbed out" with 2100 RPM, and landed with no less than 1900 'till I had all three wheels on.

Aside from skill development, there's no real need or benifit for these odd power settings. But I did find the skills useful when I was required to do partial power take offs in the Caravan for the purpose of takeoff distance data gathering, and a high power landing in it, so as to be extremely gentle with an unintended "object hanging loose beneath the aircraft" situation.

bose-x
13th Feb 2011, 12:36
Though, lets remind ourselves that the power to fly the "normal" circuit, could in many cases be about cruise power - which does not really afford the engine much opportunity to begin to gently cool down.

Cruise power in my 172 is 23/2300 which gives 128kts. Circuit power is 15/2300 which allows me to get into the 85kt white arc for the second stage of flap. There is no way that I can fly a circuit at anywhere near cruise power and still get the speed back enough to get the flap in and land.

Maybe in some aircraft you need cruise power to fly an airliner circuit to a massive runway but to fly a normal circuit then you are a very long way from cruise power and thus a very long way from shock cooling when making power changes.

I have yet to fly any variant of 172 that required cruise power to fly a normal circuit.

I fail to understand how a glide after circuit power is going to shock cool. As explained the circuit power in a 172 is very low, the engine has already cooled during the circuit, taking the power off is not going to see much more of a change and certainly not enough to shock cool.

bfisk
13th Feb 2011, 12:49
Your objective, in the end, is to touch down at the correct speed at +/- the correct point on the runway. This is valid for all aeroplanes: the C172 as much as any.

To achieve this, the power reduction becomes a factor of how close you are to your optimum path and speed, and what the trend of those two parameters are. It may sound obvious, but if you're slow and steep, you don't want to pull the power early, as you'll need the energy in the flare to arrest the descent before stalling. If you're fast and shallow, you need to bleed energy off, as you have plenty and little is required for the flare.

So it's all about judging how well your approach went by the time you approach/pass the threshold. A few extra knots? Pull the power early, anticipate the pitch down, and be prepared for a correction to this and then a flare on top of that.

Lagging behind the power curve a bit? Keep the power in in longer.
Anticipate the lessened need for pitch changes and don't over-flare as it could easily result in ballooning.

Steeper approaches are more difficult, and will bite you to a greater extent than a shallow approach, so be mindful of the PAPI or GS angle when going to different fields.

Being high or low to start with should really have been corrected earlier, although when you gain more practice, you can do "last-second" corrections to this too.

This judgment will take a while to develop, and mature with experience. However, it seems like most students and instructors like to fly the C172 on the conservative side of the book - ie with higher approach speeds than what the book says, and using these speeds there is normally sufficient energy to pull the power early (say, when the threshold disappears below the cowling).



So to sum up: be mindful of your planned approach speed and watch it as you get close to touchdown. Then decide on when and how fast to pull the power, and that in turn will dictate your flare technique. Nail it every time - and remember that a good landing is at the correct speed and at the correct position - sometimes it will be a greaser and sometimes... well, sometimes it's just another safe landing!

Pilot DAR
13th Feb 2011, 14:31
I think I see the problem....

Circuit power is 15/2300 which allows me to get into the 85kt white arc for the second stage of flap. There is no way that I can fly a circuit at anywhere near cruise power and still get the speed back enough to get the flap in and land.

Maybe in some aircraft you need cruise power to fly an airliner circuit to a massive runway but to fly a normal circuit then you are a very long way from cruise power and thus a very long way from shock cooling when making power changes.


There I am in the mighty C 150, trying to be a courteous pilot in the circuit, fly the 85 knot speed of the rest of the circuit aircraft, and not slow up the works.... 'cause I know there's a pilot behind me flying the circuit at his circuit speed of 85kts with a "second stage" of flap (I'm not quite sure what a "stage" is relative to flap in a 172, the ones I fly are specified in degrees - I'll have to fly a UK one one day, and see the differences).

If I am to countinue my courtesy, and not slow down to my normal home circuit speed of 60 - 50 knots, I'll be flying with a power setting for my normal cruise speed of.... you guessed it.... 85 kts!

When I see how rapidly, even in the summer, my cylinder head temperature will drop off, when I throttle the engine, it reminds me to always treat it with easy power changes, and minimize cold weather gliding. I extend this attempt at courtesy, to the owners of the other aircraft I fly. I have never been accused of cracking a cylinder, and I'm going to try to keep it that way. If others choose to fly differently, that's between them and the aircraft owner - that's why I don't lend my plane to many people!

bose-x
13th Feb 2011, 15:08
The question was about a 172, not the mighty 150.......

You keepmon flying in whatever way makes you happy in the 150. :bored:

Slopey
13th Feb 2011, 18:50
If it's a 172 with 40 degrees of flap on it, and you're landing at a short strip, you'll need some power on to stop it falling out of the sky. You need a fair bit of power to keep 60 kts with the barn doors out on a normal approach.

Our '74 172 lands much better with a little bit of power on down to the threshold - makes it easier to nail the speed, and as has already been said, you want to nail the speed or it'll float a fair way, and if you put it down fast, you'll get a wicked nose gear shimmy.

flyinkiwi
13th Feb 2011, 18:57
That's what I love about the 172, it's massive approach envelope means you can try different ways to land and not bend it. My advice to the OP is, at this point in your training it is best that you do exactly what your instructor sitting next to you tells you to do, even if they contradict another instructor. Once you have more hours and are more confident in the aircraft you fly and your own ability you can experiment a little.

ifresh21
13th Feb 2011, 19:46
Thanks a lot for all the help. You guys are amazing with the responses. I haven't completely read them all, but I guess both ways are good and most people use a combination

SkyHawk-N
13th Feb 2011, 19:56
ifresh21, what you have to realise is that your instructors are probably teaching you the safest, most straightforward way of landing at your particular airport. You are in your training phase and what you are taught is to give you a good general grounding and to get you through your flight test. Once you have your PPL, you get more confident and you start flying to loads of other airports you will find that you develop and use a number of different techniques to get back on the ground. There is no one right answer.

Cows getting bigger
14th Feb 2011, 15:55
I teach on 172SPs and use both techniques. I start with the 'powered' approach because it helps to demonstrate that throttle isn't a 'speed controller'; it is an aircraft control and therefore has a number of interlinked effects.

Trying to steer clear of numbers, most approaches are flown with 1500-1700rpm although the precise figure doesn't actually matter. I sometimes demonstrate landing with this power setting if a student pilot has difficulty understanding what is happing in the flare (speed reducing, AOA increasing) as the technique gives more time in the flare to observe what the aircraft is doing (not good practice on a short runway :) )

I tend to stick with powered approaches until the student pilot is achieving a high success rate and then introduce the glide (from downwind). Once these two approaches are sorted, we then discuss how each type of approach has advantages/disadvantages. Both need to be part of a pilot's repertoire although the glide is the more difficult art.

One final point. "Chop(ing)" the throttle is not necessarily a good word to use. Throttle is a variable control and deserves to be treat with some care. I prefer to describe the technique as reducing power or retarding the throttle in a measured fashion. As already stated, there are a number of aerodynamic effects when you change power and good pilots want to carefully balance these effects.

Ultimately, you will become more comfortable with a particular technique (just as most pilots have their favoured x-wind technique). As long as you understand the pitfalls of each and the times where you may need to use an alternative, you will be fine.

Pace
14th Feb 2011, 18:30
I teach on 172SPs and use both techniques. I start with the 'powered' approach because it helps to demonstrate that throttle isn't a 'speed controller'; it is an aircraft control and therefore has a number of interlinked effects.

CowsgettingBigger.

Here I am going to disagree with you :E

Both throttle and column are energy controllers.

One taps into energy from the engine the other taps into potential energy in the airframe.

A glider has no engine as such so its throttle (if you like) is the stick and in still air is the only link to tapping into the potential energy of the airframe.

Add the engine and you now have another source of energy available.
Both are sources of energy so ignore one at your peril :sad:

We are back to the old arguement of pitch for speed or power for speed neither which is totally correct as it should be pitch for energy power for energy.

pace

Cows getting bigger
15th Feb 2011, 04:18
I think we're actually saying the same thing, more or less. :O

Pace
15th Feb 2011, 09:14
CowsGettingBigger
I am aware we both know what we are talking about:)
Instructors tend towards the pitch for speed in low powered singles as the most important factor is to keep the student away from high AOA situations.
Me? I like to regard the whole thing as energy management,throttle and column.
In the citation we don't even pitch for stall recovery!
It is nose on the horizon and power out :E

Pace

englishal
15th Feb 2011, 09:49
Do you stall the Citation regularly :E

Actually it really depends where you are on the drag curve. If you are getting on the back of it then pitch for speed is the main thing. If you are flying an ILS at 100 kts you pitch for glidepath.

I learned about landings from my CPL examiner, he showed me a very short field in a C172 (then made me repeat it), coming in right on the back of the drag curve at about 50 kts for a precision landing at the end of the runway. He then stomped the brakes and had us stopped in 100m (172SP).

(He also "failed" my flaps just after turning a tight base and wouldn't let me go around and said that if I touched the runway early I'd failed :E Used floated along about 4500' of runway after crossing the threshold at about 100 kts :}. He said he was hungry and didn't want to waste time taxying....oh and that I'd passed!)

Pace
15th Feb 2011, 10:17
Englishal
Not on day to day ops :E I have annual recurrents sometimes in the sim sometimes in the aircraft. In the aircraft I have an old style examiner who puts you through the works including stall recoveries in different configs.
It goes against the grain to hold the nose up in a stall and just to go for full thrust! You power out but that's how it's done.
Short landings In a single I prefer high drag high power as you get a more precise touchdown point and more definate touchdown rather than missing the numbers and floating down the strip in an engine off glide approach.

Pace

Pace
15th Feb 2011, 14:01
As an addendum

I never understand pilots who claim gliding distance in the event of an engine failure as an arguement to support this method.

The least likely period for an engine failure is in the relatively low powered approach and landing phase.

Infact in a glide approach with the throttel closed you wouldnt know that you had an engine problem until you needed the power?

You are more likely to misjudge your glide and end up missing the numbers or too fast trying to get the numbers or floating down the runway admiring the scenery than in a powered approach.

I fully understand that instructors dont want students in high power high drag situations so the safest way for the inexperienced is a glide approach well away from HAOA situations.

For more experienced pilots juggle airframe potential energy and engine energy and drag to your advantage. It is far more accurate precise and ultimately safe method as well as giving more airfow over the wings, elevator, and rudder!

Pace

Mark1234
15th Feb 2011, 16:15
I tend towards a 'glide', approach by default because of primacy - it's what I was taught from the get-go. I can do whatever, but I really hate seeing aircraft dragged in on a long flat approach against full flap at (it seems inevitably) high airspeed. I've heard this described as a 'stabilised' approach, but to me it just looks like bad flying. Sorry.

Getting that off my chest, there was a point :) Two actually!
1) For me, the gliding range arguament is more about keeping the circuit sensible, rather than leaving the ATZ on every lap.
2) Given my 'primacy', I'm quite happy putting the plane where I want it (almost) every time off a glide. Usually I start somewhat high, and sideslip the excess. I'm actually more inclined to make a horlicks of it if I try the powered variant - so is it that the powered variant is more/less accurate, or is it just that you do what you're used to better than what you're not?
2.5) Airspeed and AOA ought to be entirely independent of the glide vs powered arguament. Pick an airspeed and stick to it either way, and know why you picked that..

FlyingKiwi_73
16th Feb 2011, 01:46
Infact in a glide approach with the throttel closed you wouldnt know that you had an engine problem until you needed the power?



This to me is the crux of the disscussion, glide aproaches have their uses for practice (i do em, and they are fun), but do it all the time as your landing technique and one day on short final you may find some sink (on my airfeild we cross a river on short final and this often happens) you need to use that throttle, cold engine? (are you using carb heat on these glides):= what happens if it fails? you'll land short and won't feel so clever.

Considering this guy is a student i'm surprised you instructors aren't all over this as a potentially dangerous practice.:eek:

Pilot DAR
16th Feb 2011, 03:00
what happens if it fails? you'll land short and won't feel so clever.


Letting alone for the moment, my sensativity to over cooling, or shock cooling engines, I do not see it as much of a risk, in this sense - as long as your "aim point" is a little down the runway. If you open the throttle find it has quit (like a cub I used to fly), you're just going to land more short than you'd planned - there should still be some runway there. If the runway is so short that you are aiming for the button, I'm thinking that you want a power on approach for a precision touchdown, so you're covered.

It is always a choice to fly a slightly faster glide, and burn off the extra few knots in a last minute sideslip, or the flare. The effect will be similar to carrying power all the way down, though the plane will still slow down more quickly in the flare, so be ready, and not high.

If in doubt, carry some power. Particularly if the plane is unfamiliar, or the eye height is different to what you're used to. The power will give you time to "feel" for the runway, and if you muff it, the power is already resulting in the nose being higher, so the plane will be more tolerant of a premature touchdown.

SNS3Guppy
16th Feb 2011, 06:56
We are back to the old arguement of pitch for speed or power for speed neither which is totally correct as it should be pitch for energy power for energy.

That argument is largely perpetuated by airline pilots who fly big airplanes that do require such thinking. In a half-million pound airplane, one doesn't have the operational flexibility that one has in a 172, when landing. Stable approaches are critical, and one is more rigidly locked into concepts such as power for speed and pitch for the glidepath. These debates end up trickling to a light airplane discussion, and it's not nearly so critical a subject (it's also worth noting that while pitch and power are very interchangeable on a light airplane while conducting an approach, they're a lot more interchangeable in a big airplane, too; more so than most of the airline-types who create these arguments may realize. It's also worth remembering that a lot of those folks do far more of their approaches and landings through automation, so their view of what you should or shouldn't be doing in a light airplane may not necessarily be your best source when learning to land the 172).

If you're high on the glidepath, you may elect to reduce power, or you may elect to pitch down, or you may elect to reduce power and pitch down. You already know that decreasing your angle of attack (pitching down) will result in a speed increase, but then if you're also pulling power back, perhaps not. Flying is the art of managing the responses you can expect from the airplane in the context of the environment in which you're operating. For example, on a calm, cold day you might expect the airplane to nose over slightly and go down when you pull the throttle to idle during an approach. On a hot day in the desert, you may find that due to the environment and thermals, you're going up and speed is increasing. So it's what you expect the airplane to do, coupled with the reality of what's really going on.

Don't get locked into a rote formula of pitch for this, power for that. Don't get locked into a practice of always landing with flaps, or full flaps. You've got all kinds of flexibility in a light airplane. Use it.

Be careful with slips. I was a slipping fool for years. I grew up as a kid flying airplanes with no flaps; slips were the order of the day. I also grew up working on airplanes, and have seen what little bit holds the vertical stab onto the airplane, and the damage that can be done to that little bit. I've seen cracked bolts and vertical stab attach brackets. I've seen damage to the airplane, fatigue, cracking stress. There's a lot of stress on that vertical stab when you're slipping.

I used to slip large, four engine airplanes, fully cross controlled, down canyons while working fires. I threw them around like a super cub. I don't do that anymore. In fact, if I do slips any more in any airplanes, they're mild at best. I learned after many years, many thousands of hours, and a lot of hands-on inspection and maintenance that what I believed as a kid isn't necessarily the best or safest way. You should be able to slip, you should understand the slip, but you shouldn't have to slip, if you can help it. It's better to plan ahead so that you don't have to.

When you do slip, however, remember that unlike adding flap (assuming you're in an airplane that has flaps), the slip is "free." You can throw sink into that approach and pull it out with abandon with a little cross-control action. Don't want the drag and the sink any more? Release that rudder and aileron, and it's instantly gone. You can't do that by retracting flaps; you lose lift and increase sink. Coming out of a slip does just the opposite; you're increasing lift without the penalty that comes from retracting flaps.

The notion of always being in a position to glide to the runway has always struck me as a foolish idea. There are many aircraft and many situation in which one can't glide to the runway. I've heard a lot of instructors insist that their students always be in a position that they can glide to the runway. While I'll fully support the position that one should always be able to glide to a landing in a light airplane, there's absolutely no reason why one should always be able to make the runway. Think about it; two minutes after you take off, unless you're staying in the traffic pattern and flying a tight downwind, you're not going to "make" the runway. Why should it be an issue when you're approaching to land?

subsonicsubic
16th Feb 2011, 13:32
I fly my mates 172 around the Philippines. We land at RPLC ( 13000 feet plus) and at Woodland (1000 feet approx) and lots in between.

I have never considered pitch alone or power for that fact. On final I'm adding/ reducing pitch and power dependant on conditions, view, airspeed and what my "pants" are telling me.

Light GA singles react very well to a burst of power if needed and I enjoy the options this give me on approach.

At RPLC I'll often spool in under power and have that wonderfull option of trading a long boring taxi for a long, sweet greaser and a quick run to the ramp.

Saying that, I almost topped myself getting under the wires and below the power curve in a 172 that "tempted" me with 40 degrees during a spot landing competition...

Every landing is and can be markedly different. It's something I celebrate in the 172.

Best,

SSS

Pilot DAR
16th Feb 2011, 16:18
Interesting as these comments are, they seem to me to somewhat perpetuate the "fly it by rote" approach, rather than "being at one" with the plane. I entirely accept that there comes a size, class, and purpose of aircraft where flying by rote is the most appropriate way. A C 172, or most other GA aircraft, are not in this category.

A 172, like most light aircraft, will respond very well to being flown by feel. So feel it, and use all the elements of flying available to you, in harmony, to get the result you want. I agree that it is unwise to actually fly the aircraft so as to conflict with good airmanship, or the recommended techniques for the aircraft, but other than that, try a varity of techniques - don't just fly it by rote, or "the numbers".

Pace
16th Feb 2011, 16:55
I've heard this described as a 'stabilised' approach, but to me it just looks like bad flying. Sorry.

Mark

There must be an awful lot of bad pilots flying heavier stuff around the world.

Its nothing to do with the size of the aircraft but being in harmony with all the forces drag and energy that is available to your aircraft.

I can understand a student whoi is not in harmony with all those factors where the instructor says push for speed as that keeps the student on the right side of the drag curve but as he gains experience he should practice energy and drag management and getting a true feel for his aeroplane?

Pace

FlyingKiwi_73
16th Feb 2011, 21:35
I agree with Pace - Thats why gliding is an excellent opportunity to learn kinetic energy management, you learn very quickly about how to manage the 'profile'.

My issue with this post was that a student is closing the throttle to perform a glide approach to land, he prefers this, maybe he has speed management issues? has trouble trimming with idle power on at 70 knts? i know i did.

Aside from the shock cooling issue, A student i'm not sure would know what to do if encountering sink on short final, especially with first stage or worse 2nd stage flap deployed, the natural reaction would be to add power and raise the nose, and i can guarantee this won't be a gentle application increasing the likely hood of losing the power right at the point you need it

At my airfield landing short on almost every runway would probably kill you, this may not be the same on some of the larger tarmac airfields in the UK, but I'm sure those drains, gutters or runway edges would bend a nose wheel quite happily.

Mark1234
17th Feb 2011, 09:42
Pace: I suspect we're talking about different things - I've seen (or rather not seen) plenty of aifcraft being dragged to the field with full flap, heaps of throttle, on such a flat approach that they're hidden behind the hedge. That's certainly not 'in harmony'. No issue with being 'on profile', but there's a matter of where, and how.

If you're flying something that approaches at circa 150kts and the engines can't go below flight idle of something like 50% thrust (and it weighs a few 100 tons..) you're going to need to be 'on profile' a hell of a long way further back than in a 172 cessna - I don't really see how 'one size fits all'.

SNS3Guppy
17th Feb 2011, 13:08
Every landing is and can be markedly different. It's something I celebrate in the 172.

Perhaps celebrating arriving at a point when you can make all your landings as similar as possible would be a better goal.

I can do whatever, but I really hate seeing aircraft dragged in on a long flat approach against full flap at (it seems inevitably) high airspeed. I've heard this described as a 'stabilised' approach, but to me it just looks like bad flying. Sorry.

Whomever described that to you as an example of a stabilized approach has provided you with an incorrect understanding.

A stabilized approach means that you are configured and stable, ready to land. How it's applied may vary, but if you're passing through short final fully configured, at a stable speed, at a stable rate of descent, with the airplane under control, then you're flying a stabilized approach to landing.

If you're making that approach to land under instrument conditions, then you should be on speed, configured, and stable by a thousand feet above the field at a minimum. This frees you to concentrate on flying the approach precisely at a critical time, rather than trying to get the airplane under control.

Most airlines use stable approach criteria that require the aircraft to be in a stabilized state by a thousand feet in instrument conditions, and five hundred in visual conditions. The aircraft may be slowing to it's final speed until that point, and one may be configuring the airplane during the approach (indeed, standard practice in most transport category airplanes for a precision approach is to apply the final configuration at the glideslope intercept point, or for non-precision, to be fully configured before reaching that point).

This works well in light airplanes, too. Unless you're an ag pilot, you probably shouldn't be rolling wings level at 50' above the field as you hit the threshold in a tight turn, while snapping out flaps and pulling power to idle. That would be an unstabilized approach.

It's hard to make a good landing out of a bad approach to land. Make a good approach to land, and you greatly increase your chances of making a good landing.

Gertrude the Wombat
17th Feb 2011, 14:47
If you're making that approach to land under instrument conditions, then you should be on speed, configured, and stable by a thousand feet above the field at a minimum.
Not how I was taught to do approaches on my IMCr course, not least because it would take about a day and a half to come down the approach with full flap.

Piltdown Man
17th Feb 2011, 15:37
A powered approach will generally be a flatter approach and appears to be the normal approach a most airfields. They appear to be flown a bit faster and a the circuit a little wider as a result. At many busy GA airfields this will allow more traffic to be circuit at the same time. So far all of these are upsides for the flying club and airfield operator. One of downside happens when it all goes quiet up the front. Where will you go? The other is when conforming to a traffic pattern, you'll often conform to the speed. In my opinion, most G/A aircraft are flown far to fast on approach. Long runways mask the real problem and that is, you may not have learnt and practiced the correct technique for performance landings. So when you HAVE to do one...

A glide approach is a nifty procedure for keeping the circuit small and tight and the noise to a minimum. When flown correctly, you are insured against engine failure (by definition) and the result will generally be well aimed touchdown and a short ground roll. The downside will often be seen when someone pulls one of these out of the bag, unannounced, in the middle of a crowded circuit. Potentially they'll be descending over the top of people on finals and be totally unaware of their presence. Cooling could be another problem as could carb. ice under the right (wrong?) conditions.

Give me the choice, and I go for something between the two. But no matter which approach you do, getting the picture and numbers right is what its all about.

PM

SNS3Guppy
17th Feb 2011, 15:46
A powered approach shouldn't be any "flatter." A standard glide path should be used. Vary it with flap use, slips, etc, but don't fly flat simply because you've got power.

Whether you're flying a flapless glide or a full-flap power on approach, your arrival to the runway should look remarkably similar each time.

Not how I was taught to do approaches on my IMCr course, not least because it would take about a day and a half to come down the approach with full flap.

Never overlook the possibility of having been taught incorrectly.

FirstOfficer
18th Feb 2011, 19:08
YouTube - What a scare! (http://www.youtube.com/watch?v=R2VQjxuhYhc&feature=related)

Talking About landings...

subsonicsubic
20th Feb 2011, 04:19
Perhaps celebrating arriving at a point when you can make all your landings as similar as possible would be a better goal.

I think my post explains quite clearly why I employ differing techniques...

Gertrude the Wombat
20th Feb 2011, 09:44
I think my post explains quite clearly why I employ differing techniques...
As a much more general rule "fitness for purpose" quite often works better than "one size fits all".

SNS3Guppy
20th Feb 2011, 19:09
I think my post explains quite clearly why I employ differing techniques...

Yes, it does, which is why I gave you the counsel I did.

corsair
24th Feb 2011, 18:13
When the 172 first gained tricycle gear, the brochure trumpeted it's 'land o matic' landing gear. Judging by some landings I've seen and.....ahem cough, cough, been on board for. Some people took that too literally. Carry a little too much speed on finals and it will float forever or at least until the hedge interrupts proceedings.

Personally like others I used to vary my approaches to match the circumstances. Flying into a 400 metre strip requires one approach style and a long airport runway requires another. The fastest I ever approached in a 172 was in Memphis, 120 mph over the threshold to avoid delaying the masses of DC9s lined up for departure and behind me.

I did come unstuck one day when I flew a 172 with a cruise prop. On a flat calm day, it just didn't want to come down. After three go arounds. I didn't know whether to laugh or cry.

FlyingKiwi_73
24th Feb 2011, 19:12
I once turned in on W1 at NZWN so fast we nearly on two wheels, there was a Dash-9 behind us and the controller was getting rather insitent. Now that was a FAST taxi. we landed long and everything, the tommies just aren't that fast.