Landings in gusty conditions

[Major Major]

Hmm, it be getting gusty out there over the next few days...

Let's say I happen to be flying a PA28-161 out of Barton on 27L and the wind was 270/15G30, so it's right down the runway but it's gusty.
Now, normally I'd drop the final stage of flaps on finals over the motorway at about 600ft (give or take) and would approach at 65Kts.

However, when it gets gusty I'm not entirely sure how to handle it. On the one hand, I've been told to nail that approach speed no matter what, so surely I'd be adjusting attitude constantly depending on what the wind was doing.

On the other hand, a voice inside my head is telling me that if I'm nailing 65Kts and the wind drops by 15Kts, I'll suddenly have 15Kts less IAS and the stall warner will probably come on...so the temptation is to go in faster, say at 70Kts, for a bit of a safety margin.

What do you guys do?

[S-Works]

Your first answer was correct almost, adjust with power, choose the position on the runway you want to land on and keep it in that position on the windscreen with power and small attitude adjustments. If you put the extra knots on for the "wife and kids" the wind drops close to the ground, on a short runway where do you intend on getting rid of the excess speed? The hedge most likely.....

[Major Major]

Thanks Bose...Given that hedges are oft mentioned as good at retarding aircraft, I've often wondered why they don't fit arrestor hedges to aircraft carriers...it would make for some nice greenery...

[big.al]

arrestor hedges to aircraft carriers

Well that's an excellent idea - they work great at Netherthorpe, so why not?

:)

[Speedbird48]

Hi Major Major,

Where were you when the instructor was teaching this stuff, or better still where was the instructor, if indeed he taught it??

A rule of thumb is to add 1/2 the gust factor to your normal speed.

Are you sure that you want to use "the final stage of flap" under those conditions??

Watch for inbound!!

Speedbird48

[S-Works]

Half the gust factor only works for lighter winds and long runways. Example, my Cessna approach speed is 70kts. Today wind is 18kts G30, half of gust factor is 6kts giving an approach speed of 76kts. Enter ground effect wind is in the ebb after a gust and you are way to fast.

It is much better to fly the correct numbers in the correct manner.

But hey what would I know.

[Johnm]

I was taught the half gust factor trick so in the example quoted difference between "steady" speed and "gust speed" is 15 knots so add 7.5 knots. However that's approach speed and you'd be wise to come over the threshold at less than approach speed if you don't want to float forever in a Warrior. The little bit of extra momentum on the glide slope helps avoid too much corrective throttle and attitude for us less than skygod pilots whenit's gusty.

My similar Archer would in the conditions you describe fly base at 75 kts final at 70 (instead of 65) and still cross the threshold at 60 but I'd be ready for a (very) little blip of throttle to cushion the touch down if the wind drops at the last second.

In fact once set up on the final approach (visual) I don't really look at the clocks and dials I look at the picture in front of me and try keep it constant until I'm ready to close the throttle completely and land.

[gcolyer]

I sort of agree with Bose.

The PA28 dakota I use has an approach speed of 77 kts. I always add the 1/2 gust factor and usually have no issues.

However the other day sure as hell as Bose describes the ebb I ended up to fast when trying to stop on a short and narrow runway, which resulted in some hefty breaking and lots of rudder pedal work.

Bose I beleive you know the aircraft and the group as the other 3 memebers are on the PPL/IR committe.

[Major Major]

I should clarify that I'm still a student and my understanding of my instructor's guidance thus far has been to nail the numbers all the way down (both on the grass and on the dials), as per Bose's advice.

I don't want to start a 'bash the instructor' thread as the half gust factor rule of thumb may well have been taught and I've just been too thick to get it - but bearing in mind the last time it was gusty we were on the (even) shorter 20/02, it might have been thought to be inappropriate given the extra few knots that would be carried down to the threshold.

You're right on the flaps; in the conditions we're discussing I'd probably not drop that final stage.

GColyer has more or less described how I end up in these circumstances - lots of rudder work and heavy braking, which is fine until you want to get down on 20/02 after a recent downpour...

It sounds like I need to be able to do both depending on circumstances - and if I can get my thottle/attidude control good enough to fly the correct approach speed, then I can certainly add a few knots for the wife and kids if I've got a 1000m runway to play with.

[Will Hung]

My advice, for what it's worth, is, forget drag flap, two stages is all you want in gusty conditions in case you have to go around. Set yourself up nicely on base at 70, don't try adjusting for IAS too much as it might be up and down like a whores drawers, then just do what you've been taught to get to this stage, control your height with power. Simple. (although it wasn't as a PUT) ! Happy landings.

[S-Works]

Adjusting speeds outside the POH is just poor pilot skills and you will get caught with your pants down eventually.

Nowhere in my POH does it say anything about adjusting the speeds for gusty conditions. It does state that all figures in the POH are subject to the aircraft being flown exactly at the stated numbers.

Learning to fly at the correct numbers is all about becoming a good and safe pilot, adding rules of thumb and old wives tales is about being an average pilot. Most of the time the average pilot gets away with it, the times that they don't makes for entertaining reading in the AIB reports or to often sobering reading...........

[flyme273]

Airliners rule is to add 1/2 the headwind plus all the gust (above the headwind) up to max 20kts.

so in your example (app70 kts Hwind 18 kt G30) add 1/2 of 18 kts plus 20 kts for gust = 29 kts. Approach speed is therefore 98 kts.

I know this will meet with some controversey and it does seem too fast.

However lets analyse what we are doing. First the gust- it means exactly that. One minute its there, the next its gone - very dangerous. If one only adds 1/2 gust then next minute one will have minus 1/2 gust - not safe.

The headwind correction partly restores the ground speed so no risk of running out of runway.

This is for Approach say 4 mls Dme to near threshold. Nearing threshold start to reduce power and round.

In practise for a Piper, I would certainly add the gust correction and maybe ease up on the headwind and use 1 or 2 stage flap subject to runway.

I would question the wisdom of flying a light aircraft on a day with G30 knots at the airport - that is a lot of wind, particularly as you are a student. I don't think I would get airborne.

flyme

[Wrong Stuff]

It's been a while since I've looked at a Cessna handbook, but from what I remember that surprises me, Bose-X. In their Operating Details section (section 2 in the old days) Cessna used to give a recommended approach speed range and suggested you adjust the approach speed dependant on wind speed and turbulence - ie gusts. Perhaps yours is a later version and they changed their recommendations.

[Major Major]

FlyMe;
Some good points there but I worry about carrying too much speed into a potentially slippy <600m grass runway, even with the ground speed due to the headwind.

Equally, if I'm going to fly the POH numbers precisely I worry about reacting to quick gusts in sufficient time to maintain the POH airspeed.

If it's straight down the runway I've been up in G30 before. I agree that a substantial crosswind would make it unflyable and I'm well aware of my own crosswind limits as well as the aircraft's.

[Contacttower]

At 65 knots in a PA28-161 you will have some difficulty keeping on the centre line in a gusty crosswind...simply because at that speed with full flap it gets quite vunerable to turbulence and tends to 'wallow' a bit in the air. I would come in with just two stages flap at 70, and slow to 65 as you come over the hedge. No faster though....the tapered wing PA28s when light will float for ages in ground effect.

[Saab Dastard]

Airliners rule is to add 1/2 the headwind plus all the gust (above the headwind) up to max 20kts.


I don't think that it is really appropriate to compare SOPs from airliners to light pistons.

Almost all airliners these days have jet engines, and as you know, jet engines have a considerable spool-up time, so it is not really practical to adopt the same "adjust RoD with power" that bose-x and others have described as the correct op for piston singles.

Airliners also have considerably more inertia, which is also a big difference to a light piston, in that it takes more power for longer to change the trajectory.

I would think that the majority of runways (of course there are many exceptions) for airliners are long enough to accomodate a longer landing run with additional / excess speed.

Finally, not many light pistons have airbrakes and / or spoilers to dump lift!

SD

[Gertrude the Wombat]

Easy.

I fly for fun.

G30 isn't fun.

If it says G30 I don't go flying.

(Actually I did the other day, when it was G30 mostly across the runway. But this was an IMC lesson so I told the instructor he could do the landing. He proceeded to show off by running quite a long way on one wheel, not something I've ever been taught to do.)

[Contacttower]

He proceeded to show off by running quite a long way on one wheel, not something I've ever been taught to do.)

Certainly I've been taught to touch down on the into wind wheel first in a strong cross wind....but as for running a long way on one wheel, that is showing off ;).

[IO540]

It's a fact of life that when it's windy it is more difficult to fly a stabilised approach and it's difficult to do the last bit too. One just has to be quite proactive with the controls - often this looks alarming to passengers who are used to you holding the yoke with two fingers. Crucially one must maintain the "glideslope" while very regularly checking the airspeed, and if it starts to change away from the target then the engine power must be quickly adjusted - all the while one is using the controls to keep the plane on the line of the approach (laterally and vertically).

Usually, the last few feet are OK because there is much less wind ON the runway than say 20 yards up.

It also helps (in terms of pilot workload) to be correctly trimmed for the landing configuration airspeed when still high up (shortly after base to final turn i.e. about 1000ft AGL) because it tends to not be too bumpy up there. Then, when it gets rougher as one descends further, there isn't any need to fiddle with the trim, and in any case it would be a waste of time because one can't trim when the thing is going all over the place.

And the more wind there is, even if straight down the runway, the more wind shear there will be. So one has to watch the airspeed extra carefully. I personally don't "add extra" for this but then I fly a 250HP plane which has loads of power. In a Warrior, I would be wary of landing with say a 40kt wind because at 1000ft it is likely to be 70kt which is 30kt of total wind shear; in fact more because the wind is measured at the top of a 10m pole and there will be considerable additional wind shear in those last 10m of height. In such a case is is going to see 40kt of airspeed gradually disappear between starting the final and touching down. In such a case one should probably add 10-20kt to the approach speed.

I've done about 700 landings to date (7 years, 850hrs TT). Only one go-around so far due to bad technique. So whatever I do seems to work for me.

[FREDAcheck]

Bose wrote:
Nowhere in my POH does it say anything about adjusting the speeds for gusty conditions. It does state that all figures in the POH are subject to the aircraft being flown exactly at the stated numbers.

Good idea to stick to what the POH says, I'm sure. The Cherokee owners handbook says:
"In high wind conditions, particularly strong crosswinds, it may be desirable to approach the ground at higher than normals speeds with partial or no flaps"
However all the landing performance charts are based on approach at 1.3VS0. Hence, approaching at higher than 1.3VS0 will result in longer landing roll.

[S-Works]

"may be desirable"

Long landing role. Does toss all for landing at Barton or Netherthorpe.......

[BackPacker]

Honestly, if you're a student or a low-time PPL, and it's gusting up to the limits of what the aircraft can handle (the POH numbers for demonstrated head- and crosswind), don't fly at all. Or, pick an airfield with long and wide runways.

Don't expect you are able to mimic the flying skill of a multi-1000 hour plus test pilot, who can land the aircraft in the worst possible conditions in the shortest distance possible.

[bookworm]

what the aircraft can handle (the POH numbers for demonstrated head- and crosswind)

I don't think I've ever seen a "maximum demonstrated headwind component". What are you flying and what is its value?

so in your example (app70 kts Hwind 18 kt G30) add 1/2 of 18 kts plus 20 kts for gust = 29 kts. Approach speed is therefore 98 kts.

I know this will meet with some controversey and it does seem too fast.

It's maximum 20 kt total increment in any publications I've seen. And FWIW, while it might work for Vref 120 kt, such a large increment seems quite inappropriate for an aircraft with Vref of 70 kt.

[Dr Eckener]

Airliners rule is to add 1/2 the headwind plus all the gust (above the headwind) up to max 20kts.

so in your example (app70 kts Hwind 18 kt G30) add 1/2 of 18 kts plus 20 kts for gust = 29 kts. Approach speed is therefore 98 kts.


Absolute tosh! :=

As to the original question, fly the numbers, and react with power/pitch to maintain the desired glideslope. Be prepared to throw it away if you get any sign of windshear, or it doesn't look/feel right. Practice makes perfect I'm afraid, so take an instructor until you get comfortable.

[Final 3 Greens]

I'd be considering a flapless landing, since ground speed would be pretty low with such a wind and the extra 5 knots (or whatever) the POH gives would assist with turbulence penetration.

Better still, I'd be using my superior judgement to sit in the bar and watch others use their superior skills to cope with such demanding conditions :}

[englishal]

I don't think I've ever seen a "maximum demonstrated headwind component". What are you flying and what is its value?
I've got one in my POH, it is called Vne :}

I'd go for two stages of flap and "feel" the aeroplane. If you need to, add a few knots. Bear in mind though that likely the wind direction and strength will change in the last few feet so be prepared for it and don't accept any drift (ref: IO's vigorous control inputs)....

Works for me....

[Ivor_Novello]

One can imagine good STOL performance in Stornoway today...

EGPO 080820Z 29039G56KT 9999 FEW007 SCT020 07/03 Q1000

[BackPacker]

I don't think I've ever seen a "maximum demonstrated headwind component".

Oh, all right. There's no maximum demonstrated headwind component in the POH, other then Vne.

What I meant was that if you have a gusting wind straight down the runway, initially it may look like there's no crosswind component. But in gusts the wind always veers, possibly up to, what, 30 degrees? So a gust of 30 knots might turn a dead-on headwind into a 15 knot crosswind component.

[Major Major]

Ah well, ho hum, was meant to be flying today but have cancelled due wx.

First, it will probably be 20G40, so that's probably beyond what I can safely handle - especially with a forecast isolated G45.

Second, it's forecast to move round to 300 during my slot. That would probably bring 32 into operation, but even then you'd be looking at a crosswind component of 7G13, which is within what I can handle but combined with everything else (and the next reason) I'm not happy with it.

Third, in addition to generaly gustiness, it's too variable, so too high a likelihood of demonstrated crosswind being exceeded.

Fourth, that big cold front moving down the country is causing rain at the airfield (so slippy grass runway) now and though it's forecast will clear up, who can really say how fast?

Fifth, yes, it just wouldn't have been fun, especially as the cloud base is reported as 1900ft - and it looks worse from where I am now, which is about 7nm away and slightly north.

Oh well, what the hell.

[big.al]

Airliners rule is to add 1/2 the headwind plus all the gust (above the headwind) up to max 20kts.
so in your example (app70 kts Hwind 18 kt G30) add 1/2 of 18 kts plus 20 kts for gust = 29 kts. Approach speed is therefore 98 kts.

Bl00dy hell if I did that in the C150A I'd have to firewall the throttle to get enough speed for the approach!

[DFC]

Approach with the recomended speeds plus half the gust up to a maximum of 10 knots.

If the difference between the mean and the gusts is more than 20Kt, go somewhere else.

If your aircraft stalls in the landing configuration at 50Kt then Vth or Vref or whatever you want to call it is 65Kt (1.3Vs) This means that you will not stall unless you get a 16Kt loss of headwind when at Vth.

Adding half the gust (8Kt) will keep you 4 knots above the stall. All assuming that you do not react and that the lul is sustained.

----------

Ignoring the gusts for a moment, if you have a headwind of 20Kt and add 10Kt to the approach speed then if you say that you can not land due to the length of the runway, it is clear that you can not land in no wind conditions.

Note that some manufacturers have yo approach at a minimum of 1.3Vs on a steady 3 deg approach to 50ft above the threshold at which point the throttle is closed. After that point, the airspeed will of course reduce and even more so when the aircraft enters the flare.

Following that method, you may have an extra 10Kts to loose at the threshold (worst case) but you will have a headwind which means that your progress over the ground is slower because of the wind and there is more time to loose the speed and still acheive the touchdown point and speed.

Even if the touchdown point is slightly deeper then the lower groundspeed will mean a smaller ground run element.

Overall provided that half the gust is used as a correction with a maximum correction of 10Kt and the runway was suitable for landing in zero wind there should be no performance issues.

Turbulence and rotor etc being something else to considder.

--------

The manufacturers do not publish a maximum headwind because they (perhaps wrongly) give pilots credit for having a bit of sense.

Could those who say max headwind is Vne, please explain their technique for landing the aircraft while travelling backwards at some 100Kt. :D

Most operators set a maximum wind for taxi because while you can make a very short landing in a 50Kt headwind, it may be impossible to taxi and there is a high risk of having the door ripped off when it is opened not to mention that if the stall speed is 48Kt then you may go the way of the C42 at Old Sarum that I saw take to the air by itself last year during some strong winds associated with a vicious CB passing through.

Regards,

DFC

[Fuji Abound]

I ended up landing in 38 G 45 (actual not forecast) or more last year after a diversion because it was 90 at the planned destination. Dont ask.

The approach was almost direct into, but the taxi afterwards proved quite interesting as did the last sector of the flight which so far as I am concerned proved a three point harness is inadequate for keeping you attached properly to the seat. :}

[Mungo Man]

Airliners rule is to add 1/2 the headwind plus all the gust (above the headwind) up to max 20kts.
so in your example (app70 kts Hwind 18 kt G30) add 1/2 of 18 kts plus 20 kts for gust = 29 kts. Approach speed is therefore 98 kts.

This is the SOP I use at work though I'd never apply that to a light single. Anyway, the above example is wrong as not only is your maths incorrect but you state that the max increment to add is 20kts and you have added 29kts!

So just to correct the above example: wind 18G30:
1/2 headwind is 18/2 =9kts
All the gust is 30-18 = 12kts
Total increment is 9+12 = 19 kts

At my work this increment is never less than 5 kts and not greater than 20kts, or flap limiting speed.

In a PA28 normal appraoch speed is around 65kts and a wind 18G30 I would probably fly in at about 80 initally to avoid boredom due low groundspeed, then slow down to about 70 at 200ft. Over the numbers bring it right back for as normal a touch down as possible!

[S-Works]

Dear me, so many old wives tales.

Fly the aircraft by the numbers. As Dr Eckner points out if it is not right prepare to throw it away.

All of these seat of your pants adding x here and there maybe fine for airliner approaches on massive runways. On a short field you will get yourself into trouble.

If the conditions are above your ability to fly the correct numbers don't fly, get some time with an Instructor and build your experience.

I have just come back in from a flight and it is 17G30 here, I flew the standard POH numbers, controlled with power and pitch and despite the severe shear caused by our hangers which are way to close to the runway managed to land perfectly safely without adding anything to the published numbers. Just the same as I had done several thousand other times.

[Fuji Abound]

Yep, I agree with Bose.

The danger is in the coming together of theory and practice.

Fly the aircraft by the numbers, be absolutely ready to firewall the throttle if required, set your mind on not landing unless it all looks ok right down to the last few feet .. .. ..

I love it when it gets windy - no one else is flying (other than Bose :)) and if you are comfortable with the conditions the landing is as much a non event as when there is a gentle breeze.

[gasax]

I to quite like flying when its windy. It is pretty rubbish for going anywhere apart from the vanishing small percentage of times when its a tailwind ( normal cruise is 90-95kts!).

But coming back onto my strip I can practise any number of variations.

The short uphill access taxiway landing - if the wind is NW its straight across the strip up I can land on the taxiway - usually with a ground roll of <100m sometimes much less

If its in line with the strip I can hover onto the top of the hill (strip goes over the top of it). A terriific trick where you can pretty much park on the spot!

About the only thing I will not do is add 20 plus knots and bounce off the end!

[FREDAcheck]

Well, I'm going to stick to the advice of Fuji Abound:
Fly the aircraft by the numbers
And Bose (who said stick to what it says in the POH). In my POH it says the "numbers" that you should stick to are slightly bigger in gusty conditions, and I read the same in my boring old Trevor Thom, and in Plourde (The Compleat Taildragger Pilot), and Everett (Beyond the PPL). And maybe in Langewiesche, if I could find it in his worthy if long-winded prose. As has been pointed out, if you add half the gust component, this is likely to be less than the headwind (unless it's gusting from zero), so the ground speed is going to less than in still air, so landing roll ought to be no greater than in still air. Or am I missing something?

[S-Works]

Yes............. When the gusts stops and you are 8kts too fast as you touch down. 8kts in some aircraft especially low wing pipers is a lot of float on a short strip leaving you relying on the arrestor hedge.

[Major Major]

I'm going to dig out Langewiesche tonight for a look - I tried last night but got diverted onto something about rudderless safety planes...

Definitely agree with Bose on that - half the headwind plus all the gust in the PA28-161 would, in my limited experience, definitely require use of the arrestor hedge.

Half the gust would mean an approach at 80Kts with 2 stages of flap and that's exactly what I got bollocked for last time it was gusty.

So the only answer is to nail the 70Kts approach speed all the way, don't drop the last stage of flap...

[Slopey]

While I'm gazing out of my window with 28G46 and wheelie bins trundling down the street of their own volition, what do the big boys operate at? What's the xw limit on a 737 for example, or an Embraer RJ-145 (cos one of my mates has doubltessly landed in that in one a short time ago)?

Any of the heavy metal drivers (hiding in the PF forums) know?

[FREDAcheck]

So the only answer is to nail the 70Kts approach speed all the way, don't drop the last stage of flap...
If you don't drop the last stage of flap, then 1.3Vs is bigger than with full flap. For example, with a Cherokee, Vs reduces by about 3kt with each extra stage of flap. Hence the "book" numbers are greater with reduced flap. However, as Bose warns, beware of short runways. Most POHs will give charts of runway length required at various landing weight, temperature and head/tail wind and with a specified flap setting. If you decide to add half the gust headwind component (or half the total gust component) then you have more stall margin if the headwind drops in a gust, but as Bose points out, you're then outside the manufacturer's conditions for landing length. And ground roll increases with something approaching the square of the ground speed at touch-down.

Bose and other experienced pilots probably don't need the extra margin as their reactions will be quick and accurate in gusts. Less experienced pilots might prefer the margin. I don't see anything wrong with that - provided the runway length is sufficient, as Bose points out.

[yoohoo748]

A plane is a plane. Lift, thrust, drag and lift. Lose your headwind component and you may be in for a world of hurt. An additive will ensure safe operations.
I can't recall what the manuals said in the light singles or twins that I have flown, but I do recall adding 'some' when it was windy and gusty. On the MD-83 we added either ½ of the head wind component or all the gust, which ever was greater, to a max of 20 knots. On the B767 we do the same, but combine the two.(again, max 20kts) Keep in mind, for those of you that are worried about over running the stopway, that with the additives your ground speed will be reduced by your headwind component. Thus, if your approach speed is 70kts, and you add 15 because the wind is 20 gusting 25, then your approach speed will be 85, but your ground speed will be 65. Once crossing the threshold, your additive for steady state wind is to be bled off and your correction for gusts maintained, so that your IAS will now be 75, and ground speed will be 55!!!
Any average pilot should be able to, without much effort, stop his a/c in a shorter distance on a nice gusty and breezy day in shorter distance than on a calm day. Perhaps on a light a/c your additive might be 5 or 10kts max, or something like that... I don't know. Play it safe. Don't try to be a hero. If the approach looks like it is going into the toilet, abandon the approach and try again.
Oh, and I hope my math was correct for the above now that I am looking back up at it. Please correct me if I am wrong.
Slopey... B767 company limit 33kts dry. MD 83 was 30 demonstrated. I think.. at least that. Did that with no problems. HS748 was 30, again if memory serves correct. Did that too, no problem... very nice handling plane. Worst wind I saw was in Churchill, about 30 or 40 degrees off the runway 49G60. Made for a very short landing. I'm not bragging here as I do believe that I am not an elite pilot of any sorts. Just been there and had to do that.
I hope this helps. Cheers.

[S-Works]

Except that wind speed is given 10m above the runway, the speed 10m down can be significantly lower. In a 737 etc that makes little difference in a spamcan it is a huge difference.

You only have to look at the AIB reports to see the number of people who have made this mistake on short fields.

There is no way I would want to be whistling along the runway at barton in a cherokee at an IAS of 75kts regardless of the headwind component at 10m......

As has been pointed out several times in this thread, the additions work fine for large aircraft on large runways, on a small aircraft the type of increases you are talking about are massive increases over POH values.

Perhaps the reason why airline pilots often struggle with a return to light aviation after a period away.............

[DFC]

Aircraft X has a stall speed of 50Kt and an approach speed of 65Kt with landing flap. With a level grass runway, including the safety factors, the landing distance required is 600m

Flight Manual recomended technique is a steady approach at 3deg glideslope to cross the threshold at 50ft and 65Kt. At this point the throttle is closed.

Now let's say that the wind is 10G20.

Approach speed 70Kt (Vth + gust/2)

Ground speed at the threshold is;

60Kt with no gust and 50Kt with the full gust.

Now if the aircraft can land in 600m when the groundspeed at the threshold of 65Kt can someone please tell me why it will run off the end when the groundspeed is less.

The only reason why adding half the mean wind is not recomended is the problem with trying to get rid of all that airspeed.

As a pilot you are expected to cross the threshold at a speed of Vth +15/-0Kt. If you can't do that the CAA will not give you a licence.

15 knots fast in 0 wind will eat into your 1.43 safety factor. However, using the half gust factor maximum 10Kt, you would never be that fast if you fly accurately.

The big jet on the big runway can be even more limited in terms of performance. In other words, it needs every metre of that big runway.

Regards,

DFC

[S-Works]

because when the CAA give you a license those tolerances are fine within your experience. As your experience increases those tolerances decrease.

because as I pointed out the wind is given 10m above the threshold, if you are carrying that extra speed at the tarmac or grass on a short runway you may have a problem.

There is nothing difficult about flying the correct speeds and developing the skills to fly the correct speeds in all conditions.

[DFC]

because as I pointed out the wind is given 10m above the threshold, if you are carrying that extra speed at the tarmac or grass on a short runway you may have a problem.

There was I thinking that the approach ended at the 50ft point crossing the threshold and from that point on was the landing.

If you read most cessna and piper manuals, you will find thew following;

Steady approach to cross the threshold at 50ft, Throttle closed landing.

If you maintain your approach speed to the tarmac then you are not flying as the manufacturer intended.

What we are talking about is a safety adjustment to the airspeed to ensure an adequate margin above the stall during thre approach to the 50ft point.

I don't know about your aircraft but when I close the throttle, drag takes over and the aircraft slows (quite quickly with landing flap).

Before arguing about exact book approach speeds, one has to remember that in many cases, landing distances are only published for landing flap settings. Using zero flap with no performance figures is just as far outside the flight manual performance figures as adding 5 or 10 kt to the approach speed with landing flap.

The wind is measured at 30ft because it is clear of errors caused by surface effects in the vicinity of the annenometer and since the landing starts at 50ft, is a good indicator.

Regards,

DFC

[S-Works]

Silly me, of course you always know best. I will of course bow to your superior experience and continue on the way I have always done. Perhaps one day I will bring a smirk to your face when I get it wrong.....

[RatherBeFlying]

In my two glider outlandings, I have had the time and opportunity to pace out my touchdown point at about 100 yards in after a 50' margin over a putative 50' high power line and rollout distance at about 50 yards from a 55 kt. approach.

This gives me a final approach segment of a 1:3 slope or 18 degrees. As that 100' is an estimate, I can postulate being as low as 75' which would yield a 1:4 slope or about 13 degrees.

Note that these slopes are considerably steeper than your standard 3 degree ILS.

Gusty conditions normally come with strong winds; so, a 3 degree approach can get you low well before getting to the runway and you may well find yourself needing considerable power to get back up to a safe glideslope.

Of course, if you are conducting an ILS approach, you do have the advantage of a properly surveyed approach area, but most rural runways without instrument approaches tend to have trees, powerlines etc. in much closer proximity to the threshold.

Also a 3 degree approach will dump you short of the threshold if the engine quits.

As for speeds, remember that they are based on gross weight. After a few hours of fuel has burned off, the approach speed can be corrected by the factor:

sqrt(landing weight) / sqrt(gross weight)

You may already be adding 3-5 kt. to the proper approach speed and this can definitely influence the float in a low wing a/c.

Just before entering ground effect can be a good time to get rid of some of that added speed for gusts, provided that the gustiness has reduced.

Flaps can reduce aileron control, which is why reduced flaps can work better in some a/c.

Stronger gusts and crosswinds are something you have to work up to in a controlled fashion. Recency in strong winds in type counts for quite a bit. If I've been away from flying a particular a/c for a while, my next few flights will be in gentler conditions.

[Flying Binghi]

For the inexperienced -

A stall on short final has a far higher fatal probability then a landing over run.

In gusty conditions, a slightly faster then normal approch speed gives the opportunity to feel the air for the unexpected - and go around if you don't like it.

Refer to your instructer for guidence about the aircraft you fly.

[HappyJack260]

I was landing my Pitts S-2C the other week during an aerobatics contest. The windsock was showing about 30kts + (made flying within the aerobatic box at probably rather higher winds quite interesting).

The way I've been taught to land is to nail the glideslope and attitude, then adjust with power. In the Pitts you don't really have much time to keep looking at the ASI after turning onto finals and you can't see much of the runway either. The trouble is that, to maintain a given glideslope into wind, you need to adjust with throttle, but this makes the approach speed faster. If you just nail the airspeed, you end up with a very steep descent.

So on one approach, I've come in at the right airspeed, flare at the right height, and look out to the side in the flare to judge my height. Relative to the runway, it feels like I'm high and very slow. Which if kept things going would probably mean I'd have a groundspeed of around 40kts instead of 70 kts, manage a 50m landing roll and be stopped in record time.

Instead, I convince myself that I'm about to drop like a stone and bounce like a superball. So I put the power on and go around without even touching. It took me most of the weekend and half a dozen approaches to manage a consistently decent landing...

[gasax]

Welcome to the hovering landing.

On the top of my strip the wind speed is usually higher (big round topped hill). So if you aim for the apex of the hill your ground speed can get into single figures. Controlling height with power suddenly makes a lot of sense.

On the other hand aiming for the threshold puts you into serious turbulence and occasionally some wind rotor - definitely to be avoided.

If I could find a way to taxi to and from the strip in high winds then I guess VTOL would be possible.

[flyme273]

Mungo Man

Error in maths well spotted (I rushed the mail as the canteen was closing, halfway down in the elevator I realised I had goofed – was hoping no-one would spot it).

I concur with your approach (pun:p ) a nominal increase aids comfort and makes the task easier. However you do not mention any preferred flap settings?

My Flight Manual states:
for normal approach: flaps “as required” speed 75 kts
final flaps 30 deg 65 kts
final flaps retracted 70kts
crosswind: flaps in minimum extended position required for nature of airfield, airspeed not stated.

Perhaps a little vague? or open to various interpretations?

Reduced flap would imply more speed, so its all within the Flight Manual recommendations.

[gcolyer]

Well I managed landing at Perterborough Conington this morning with no problems. The wind was 31018G25 landing runway 28. It was pretty bumby all the way down the glideslope. This time I used Bose-X's advice and pegged the numbers all the way down, which worked fine other than the stall warner screaming everytime i got bumped.

The return flight looks like it will be even more bumpy as the winds have picked up an extra 10kts

[Mungo Man]

There is no way I would want to be whistling along the runway at barton in a cherokee at an IAS of 75kts regardless of the headwind component at 10m......

As has been pointed out several times in this thread, the additions work fine for large aircraft on large runways, on a small aircraft the type of increases you are talking about are massive increases over POH values.

Well, you wouldn't want to maintain appraoch speed until you are over the runway, that would be foolish.

Not all 'large' runways are large when you are flying an airliner. Some of the runways I use at work may look big but are actually relatively small for the aircraft size. Nonetheless we still add up to 20 kts to the approach speed if we need to. However, we must slow down and touchdown at the given Vref for the weight in the touchdown zone. So regardless of approach speed it is still imperative that we touchdown in the right place at the correct speed. I am told to aim to reach Vref at 50ft, which should be when I cross the start of the runway.

Perhaps the reason why airline pilots often struggle with a return to light aviation after a period away.............

Just because we land on 'big' runways doesn't mean we can't control speed.

At the end of the day you can approach flat out in a C152 as long as you slow down at some point and land on the numbers at or near to the stall speed.

[whitehorse]

Interesting thread. Just got back to base after fighting 60kts mean wind to G75kt winds 30degrees off the the runway, no we didn't land! As a professional pilot flying DHC7´s (C172 on steroids) and an FI in the UK, my experience for what its worth is this;

1. I agree with Mungo Man, the SEP pilot should not go down the ½ headwind plus gust speed. In my experience most pilots end up with a threshold speed which is too high and therefore the landing distance is too long due to the float.

My company has changed the procedures from the above to just following the laid down speeds for the different flap limiting speeds and working the throttles.

2. I agree with Bosse X that the aircraft should be at threshold speed at the threshold.

3. I agree with DFC, if you don't like it go somewhere else.

In my humble opinion a light aircraft pilot should not use trail flap in gusty conditions, what those gust limits might be depends on the experience of the pilot.

I teach plus 5kts on approach but nail the threshold speed. Making sure that there is not too much friction on the throttle.

Don't forget the breaking action. Landing on wet grass etc is going to effect what happens when you are on the runway if there is a crosswind as well.

I don't want to change the thread but in my opinion the weather is not as stable as it once was with gusty conditions becoming more more of an issue.