PA28 Approach Speeds on Finals

[ChiSau]

Would be grateful for any thoughts on this from experienced PA28 drivers.

I did my learning on a c152 and then, like many people, moved on to a PA28 161 Warrior to do most of my flying. I am still a low hour (c65) PPL having only passed in November.

My question is this: I believe I was taught that my approach speed on finals in the Warrior should be 65 kts. Having flown out of a different airfield recently with a different instuctor, he teaches approach speed 75 kts and over the numbers at 65kts - favouring more speed on approach to give better aileron response but was very keen to stress the need to make sure you weren't too fast over the numbers.

Any thoughts?:confused:

[2WingsOnMyWagon]

I do 70kts on final, and 65kts over the numbers. You dont want to be fast over the threshold, as the warrior tends to float.

:ok:

[Jhieminga]

There's something to say for both approaches to the problem. There's nothing wrong with turning final and settling down to 65kts and staying there until touchdown, but there may be some advantages to a slightly higher final speed.
- Indeed better aileron control
- A better margin in gusts or turbulence
- Perhaps ATC/other pilots will appreciate it as not every airplane at your field goes that slow on finals (just imagine you flying a couple miles of final at 65 with a twin behind you).
The drawback is that you will have to let the speed bleed off just before reaching the runway, which will take some getting used to if you haven't done this before. If you don't then indeed a PA28 will float, and all your landing length calculations will go out the window.
In my view 75 on finals is a bit quick, 70 might be better for starters. It is up to you if you want to use it but in lesser weather it is always a safer bet to have a couple of knots extra.

[Bodie]

ChiSau

I'm in an Archer 181 so it may be slightly different, but it's still a PA28.

I usually approach at 70KIAS too. However, I fly out of a short strip, so always have full flap on short final. When I select full flap I reduce my approach speed to 65KIAS with 60KIAS over the numbers.

If I were landing on a longer runway I would take 2WingsOnMyWagon's approach speeds. Like he (or she) says, the PA28 can float like hell.

If I were landing on any strip in strong winds, I would always approach at 70KIAS with 65KIAS over the numbers. The lower groundspeed makes this feasible, and if the wind drops you should encounter less sink (and hopefully not hear the Stall Warner!).

It’s a good point your different instructor made about the aileron response, I find the PA28 much sloppier in slow speed configurations than the C152. However, I still use the approach speeds just mentioned.

Bodie

[Final 3 Greens]

Chi Sau

The key is to arrive at the threshold at the required speed, which if I recall for the -161 is 63kias (but check in the POH)

If you can fly an approach that allows you to get there at this speed, that's fine.

Some of us who have a few hours in PA28s will tend to come down final at 70kias or even 75, knowing that pulling the power back and raising the nose will give pretty instant speed control when need (she isn't a slippery jet!)

Personally I use little power and full flaps, but approach down a glidepath of about 5.5 degrees, which is quite steep - I'll be looking at 600-650fpm down on the VSI at 65-70kias.

This lets me fly a short final approach (necessary at the field where I fly PA28s) and is also some insurance against engine failure.

I've also seen people fly a 3 mile final on the PAPIs at bigger airfields.

You might wish to consider working out a point (e.g. 300 feet agl or 1 mile) where you want to be stabilised - i.e. airspeed where you want it, power set, carb heat on, sink rate circa 450-500 fpm etc. That gives you a nice comfortable short final approach.

Just a point about aileron authority, the '28 does respond nicely to a squeeze of rudder on final - I use this to maintain the centreline if the nose drifts a little.

[Hersham Boy]

I'm flying an Archer now, if it's relevant. I was tough to go for 2 stages of flap on base and settle the a/c at 80kts (as it's rather wallowing at 70kts) and then to apply third stage of flap on short final and speed automatically comes back to 70 kts if you're trimmed right (it always has for me, and I'm seriously tyro, so I guess it's true!)

I'm not looking at the IAS over the numbers, to be honest, but I would guess that I'm prob closer to 65kts. And it lands luvverly.

Hersh

[Flap40]

At the school where I used to teach we used 75kts if flapless, 70kts with flap25 and 65kts with flap40.

On the -161 2300rpm will usually give you 100kts cruise (ie inside the white arc), if you reduce power to 1500rpm for the approach and select flap25 and hold the fwd pressure on the column as the aircraft decelarates it will stabilise very nicely at 70kts (give or take a couple) without having to ****** around with the trim!

Editied to say b.u.g.g.er instead of ******:= := := :=

[Genghis the Engineer]

"The airplane should be trimmed to an initial approach speed of about 70KIAS with a final approach speed of 63 KIAS with flaps extended to 40°. The flaps can be lowered at speeds up to 103 KIAS if desired".

PA28-161 Cherokee Warrior II Operators manual, as revised 20 Nov 1981. Para 4.29 "Approach and Landing".

G

[Lowtimer]

*HEALTH WARNING - I am not an instructor, please take the following as something to discuss with your instructor, not as any kind of final wisdom*

The threshold speed, which in my Warrior manual is 63 KIAS, for a full flap approach, is the important one. You can quite easily fly all the way down final approach at that speed but it's not normal practice, most schools teach you to decelerate as you progress down the last few hundred feet of final approach. This helps guard the inexperienced and / or unwary against wind gradient, and also teaches you to cope with flying an accurate approach path despite changes in speed and nose attitude - all of which learning will serve you well in later life as you progress on to slicker types and more spohisticated kinds of flying (e.g. it may be desirable to come down an instrument approach at a much higher speed for traffic separation, then you will make quite a large adjustment in speed as you transition to touchdown).

However, one thing people don't seem to talk about much in most PPL training is weight. That 63KIAS Vat is for max gross weight and should be correspondingly reduced at lighter weights. Stalling speeds and target threshold speeds (based on stalling speeds) vary with the square root of the variation in weight, e.g if you increase the weight by 21 per cent (121% of the original weight), you need a 10 per cent increase in threshold speed (110% * 110% = 121%.

Take a Warrior or Archer with not much kit on it, ten gallons of fuel a side, and a skinny solo student and you are hundreds of pounds below max gross weight. This is a leading cause of people in taper-wing Warriors and Archers floating all the way down the runway. Fair enough, no-one wants their training aeroplanes being stalled on final approach , and early stage students cannot be expected to nail the speed within one or two knots every time. A 10-knot trickle into the overshoot will not normally hurt anyone whereas a stall into the undershoot is a possible killer. But I really do think, later in training, this is something that PPL instructors should explicitly address, and I would encourage more advanced students / newly qualified PPLs to ask them about it.

[StrateandLevel]

75 Kts is OK on base leg, but once you turn final, reduce to 70 Kts. When you select the 40 degree flap setting, it will reduce the speed by 5 Kts to you thereshold speed of 65K. The attitude picture remains constant, retrim and there you are!

[Flyin'Dutch']

Nobody here seems to refer to the basix

Vat = 1.3*Vstall (in that config)(+10 if conditions require)

Nowt wrong with taking your machine to the stall whilst exploring the envelope and taking a note of the stall speed in the various configurations.

Then:

What PA28 are we talking about?

A -140 is a lot lighter and has a different wing than a -235.

As stated here the POH is a good starter and but will give speeds for MAUW.

I am a bit concerned about:

A 10-knot trickle into the overshoot will not normally hurt anyone whereas a stall into the undershoot is a possible killer.

See what you are saying but every year there are more AAIB/NTSB accidents from people going in at the far end than doing a straight forward stall on the approach (not saying that there are not a lot of stall/spin accidents with people skidding in with nose high attitudes and the following spin, but I am now talking about stalling on the approach/finals bit)

And if people have problems with speed control, and I am not talking about the last 1 or 2 KTS, but am talking about having to fly 10 kts too fast, they would do well to brush up on this skill.

As always FWIW

FD

[QDMQDMQDM]

Talking about approach speeds...

http://www.supercub.org/phpBB2/viewtopic.php?t=1139

QDM

[ChiSau]

Thanks guys and girls for the comments, as usual PPRUNE proves to be an invaluable training aid. The point about weight is a particularly good one and one I hadn't considered before.

Out of interest......when I was doing the conversion from a C152 to the PA28 I was taught by the instructor to do a finals approach at 75kias (the best glide speed) all the way to the threshold. When I queried this with another instructor, because it seemed a bit fast, I was told to approach at 65kias!

At the risk of trying people's patience, does your advice change if its a glide approach??

[QDMQDMQDM]

The point about weight is a particularly good one and one I hadn't considered before.

It's the critical point, as the Super Cub article graphically points out. Stall speed increases with weight and therefore if you use 1.3 X stalling speed in the landing configuration as your rule of thumb approach speed you can only really do that with an idea of what your stall speed is at your current weight.

It is instructive that the military Air Observation Post pilots of the 60s, flying Auster 9s, used to do a stall in the landing configuration on more or less every flight to see what the actual stall speed was.

At the risk of trying people's patience, does your advice change if its a glide approach??

With a glide approach, you want to make the field at all costs, therefore you fly at best glide speed for distance until you're sure you can make it in, then drop flap and slow down and hope like hell you don't undershoot! There's no sense rounding out in the right place, but 10kts too fast and floating over the runway to the hedge beyond. The thing to watch out for is the transient ballooning effect as you bring the nose up to lose speed which for a moment makes you lose height less quickly. But only for a moment.

You need to read Stick and Rudder. ;-)

http://www.amazon.com/exec/obidos/tg/detail/-/0070362408/qid=1044544050/sr=8-1/ref=sr_8_1/102-1768203-6423352?v=glance&s=books&n=507846

QDM

[Lowtimer]

Flyin' D,

I entirely agree with you - when I said...
A 10-knot trickle into the overshoot will not normally hurt anyone whereas a stall into the undershoot is a possible killer.
... I was simply acknowledging some of the concerns that may lead to some flying clubs encouraging what in my view are excessively high approach speeds, especially the idea that you have to use max-gross speeds even when very lightly loaded.

Agree also that no-one should be out on their own in they can't hold the speed within 10 knots.

Yes, there is a lot to be said for going up to a safe height and seeing exactly what your aeroplane can and cannot do at a given threshold speed, and getting an idea for the stalling speed at today's weight, and 1.3vs is a very good rule of thumb for threshold speed in a given configuration. The only thing I'd add is that a few types do seem to suffer from disproportionate amounts of position error right at the very low speed end of the scale, and this can distort the calculation a bit, which is one reason why a POH for a certain type might possibly give an indicated Vat which is some way off 1.3Vs

[Genghis the Engineer]

Am I the only person here troubled by the fact that there seem to be instructors out there who are not so much expanding upon the advice in an approved POH for a certified aeroplane (which is inevitable) but actually changing it.


Incidentally lowtimer, the certification requirement for most light aircraft is that from 1.3Vs to Vne the ASI should never be more than 5kn out. There is no requirement for accuracy below that speed other than it must be documented so in terms of determining 1.3Vs in IAS you are quite right. My experience is that most light aircraft ASIs underread near the stall, which means that 1.3Vs(ind) could be dangerously slow.

G

[Final 3 Greens]

Flying Dutch/QDM

I think that you'll find 63kias to be (for all practical purposes) 1.3Vs for a PA28-161 at gross.

Where the fun begins is when you're below.

There is a formula in some SEP POHs to reduce airspeed by "x" knots per "y" lbs under gross, but to my best recollection, Piper do not do this.

The further complication, to the very good point about stalling every flight that QDM made, is that it is quite possible to take the airspeed on a lightly loaded Warrior to the bottom stop (due to position error) with full flap and still keep flying! I think I recall Ghengis once making this point too <apologies to him if I have misquoted>

So there is a bit of a prob if wishing to get really accurate.

Genghis

You make the point much better than I - we must have been typing at the same time!

[Genghis the Engineer]

I've certainly seen that on one or two aeroplanes, but I don't think the Warrior is one of them.

There's a fun little Italian STOL aeroplane called a Savannah which certainly does that (in flight test we put an extra low speed ASI on separately, I think it was actually stalling somewhere around 15-20KCAS).

G

http://images.photobox.co.uk/dev/raid/s/0/9/7/97494/211544/2131482.s.jpg

(This thing)

[Final 3 Greens]

Wow

What a cute looking little plane - are those flaperons by any chance?

Bet you don't need too much runway with that one. :D

[Genghis the Engineer]

They are permanently offset flaperons with twist to give washout with a parallel wing. You can also just about see on the picture the permanently out leading edge slats.

I did about a quarter of the UK certification testing on it, the rest done by a chap who had spent about ten years in Africa as a missionary pilot. I was scheduled to be in the right hand seat for the t/o and landing tests, but after watching him doing the first few I politely suggested I (with far less hours on type and none of his bush flying experience) should do it since nobody was going to approach the performance he was getting. He agreed and we got a field length about double what he had.

Which, adjusted for still air, was 130 metres (460ft) to a 50ft screen height at MTOW.

By jove that was fun ;)

They're at www.sup.uk.com if you're interested, I'm not sure why it's not quite certified yet since we finished flight testing almost a year ago, but I saw the company in December and they were optimistic about "very soon".

G

[ETOPS773]

I personally like the way I was taught,90-80-70
90 Downwind,80 base,70 final,65 last 200ft.

I usually fly upto the tabs with 2 pax.

[QDMQDMQDM]

There's a fun little Italian STOL aeroplane called a Savannah which certainly does that (in flight test we put an extra low speed ASI on separately, I think it was actually stalling somewhere around 15-20KCAS

Stick vortex generators on a Super Cub and it will get very near to that when light. The thing I've never understood though is how you keep an aircraft with such a low stall speed (=flying speed) on the ground when it's windy.

QDM

[Keef]

I've been told all sorts of approach speeds for PA28s, and I'm sure the folks who told them to me were convinced they are right. Problem is, they aren't all the same.

I tend to read the POH (I know, I have no imagination) to see what that says.

For the PA28-140 that I learned on many years ago, the book said Vso ranged from 39 to 50 knots depending on weight. That gives a Vat of 51 to 65 knots. I wrote all that in the front of my logbook, just so I knew where to find it.

The Arrow I fly now has a quoted Vso at MTWA of 60 knots (no information is given for lower weights). I use 80 knots all the way down, aiming for 70 over the fence if it's a short runway.

Works a treat.

[Final 3 Greens]

Keef

I use the same speeds for an Arrow 4 - works beautifully as you say, juts find that one has to pull a bit harder to make the T-Tail earn a living; what model Arrow do you fly?

Didn't remember the VSo varying so much on the -140 (mid you, I've got to the age where that isn't surprising ;) ), but the lower end numbers certanly show why it's difficult to be certain about the minimum safe approach speed on a very light PA28.

Add in position error and Genghis' comments about ASI errors and typical under reading and this is probably reason enough for a new PPL like the original poster to be conservative and use 63kias (POH VAT at gross.)

Genghis

I missed the slats! Must try to find one of these when available and have a go.