Why no Crosswind Component info on final?

[SEP Flyer]

I suppose this is a question really aimed at those in the tower on the radio - on finals I am given the wind direction and speed, but never the crosswind component, which I would find very useful, especially as I tend to fly small planes where crosswind limits are low, and my brain is is concentrating on landing (the old brain is getting on in years).

On those days where the wind is moving about (being sporty), being given the crosswind figure would be such a help - if for no reason than to let me know if I'm outside the aircraft limits (which could be an insurance issue if anything happened?) - doing some last second maths with the runway rapidly filling my windscreen has never been my forte! I was wondering if anyone else has thought of this - or do some airfields give this info (without the pilot having to work it out!)

So why is the crosswind component not given as standard?

Thanks for any thoughts!

[RedsBluesGreens]

Sounds like a good idea. Personally, I do a quick crosswind calculation in my head as soon as I've got the ATIS or as I'm given the information when joining. It gets it out of the way before everything gets going for the landing.

[SDB73]

I think it's an interesting point, but ...

Crosswind component CAN be worked out with the wind info. Why not give you the headwind component as well? It'll end up getting very verbose if it all comes over the radio - especially when busy.

Also, you'd end up getting "blah blah, crosswind component 2 kts" and other things which are just of no issue to the majority of aircraft. It would also get complicated when you start having to say "varying between 2 and 12 kts".. and even worse, how do you say "varying between 4 kts to the left and 6kts to the right".

The info we get is enough. Then as cpt you can make a decision whether it's "way inside limits" or "ohh.. in that case I better work it out properly"

[RedsBluesGreens]

And I guess liability could be an issue. Really it's up to us to make the decision to land, and if ATC are doing a new crosswind calculation for every a/c on final then there's bound to be a problem sooner or later with a pilot blaming ATC for his a/c going in the ditch because he's out of limits.

[foxmoth]

Air traffic would have to work it out as well and why should they be better at it than you? probably liability issues as well if they get it wrong. Actually, very easy to work it out -take the angle off the runway and apply that to a clock face, i.e. 30 degrees off is 30 mins so half way round, 40 degrees is 40 mins so 2/3rds round and that is the amount of total wind to give you Xwind component - over 60 degrees the difference between actual xwind and full wind is no worth worrying about - and you are on the safe side!

[FlyingStone]

especially as I tend to fly small planes where crosswind limits are low

Maximum demonstrated crosswind component does not equal maximum allowed crosswind component and I don't remember seeing crosswind limitation in any small aircraft I've flown. Personal limits are of course entirely different story - especially for student pilots and low-hour PPLs.

[Pace]

if for no reason than to let me know if I'm outside the aircraft limits (which could be an insurance issue if anything happened?)

Flying stone is correct! demonstrated is just that! a figure that any average PPL should be able to handle and no indication of what the aircraft is capable of handling in the right hands!
i would go as far as saying that an aircraft can handle twice or even more of the demonstrated component. Demonstrated is not a limiting issue.

Of more importance is the pilots limiting component not the aircrafts and for some that may be a light breeze of just above zero from the right or left!!

Pace

[n5296s]

Luckily there's an easy way to work it out, close enough anyway. You don't need any fancy charts, computers etc.

Suppose the wind is reported as 12 @ 350 and runway is 31.

First work out the relative bearing. RB = 350 - 31*10 = 40 degrees.

Now xwind component = wind speed * RB/60, i.e. 12 * 40/60 = 8. If RB is >60, then x-wind = wind speed.

This is as close as the reported winds are ever going to be accurate anyway, and dead easy to do in your head. Worst case error is about 15%.

[bookworm]

So why is the crosswind component not given as standard?

The scene is set 15 years ago:
Seasoned Cambridge ATCO: "G-XX clear for take-off runway 23, surface wind 140 15 gusting 25"
Young Mooney pilot: "Clear for take-off G-XX"
Seasoned Cambridge ATCO: "That's straight across, you know"
Young Mooney pilot: "Roger"

I took off. It wasn't pretty, but we survived. Lesson? You are indeed pilot in command, but that doesn't mean that you can't take hints. ;)

[foxmoth]

Luckily there's an easy way to work it out, close enough anyway. You don't need any fancy charts, computers etc.

Suppose the wind is reported as 12 @ 350 and runway is 31.

First work out the relative bearing. RB = 350 - 31*10 = 40 degrees.

Now xwind component = wind speed * RB/60, i.e. 12 * 40/60 = 8. If RB is >60, then x-wind = wind speed.

This is as close as the reported winds are ever going to be accurate anyway, and dead easy to do in your head. Worst case error is about 15%.

Not sure about other people, but I found that a confusing explanation of the clock code I explained earlier - and in reality you only need the 15/20/30/40/45 degree off ones which are the easy ones to work out - anything below 15 degrees off is not normally worth worrying about, and above 45 degrees I would work out the 45 degree amount and estimate from there, knowing that at 60 degrees I am looking at full Xwind.

[GeeWhizz]

Air traffic would have to work it out as well and why should they be better at it than you?

With the correct (standard?) equipment fitted in the tower, the cross wind is displayed on the same screen as the current "instant" wind, the 2 minute wind, the 10 minute wind, and maximum gust within a similar time period but I forget whether its 2 or 10 minutes.

I think SDB73 is close to the reason of not providing the crosswind on final, as it would become very verbose. Also worth considering is a change in wind direction of a few degrees or a change in strength by a kt or two the crosswind is likely to change more significantly than the mean surface wind. I'll gladly be corrected if I'm talking rubbish here.

However there's nothing wrong with actually asking for the crosswind when you're on final, if it available I'm sure whoever is in the tower will happily provide it.

GW

[Pace]

But what is the point of knowing the crosswind component?
Far more important is to know the wind strength and direction as well as the gust factor.
To me windshear is far more hazardous than knowing the crosswind component is 17 kts instead of 15 kts?
A demonstrated crosswind is just that! It's a guide for the average pilot.
If your better than average you will cope with more if your less you won't manage that limit anyway.
It's the big picture of handling something which is inconsistent near the ground and that is winds.
Anyway the last thing you want to be doing in strong winds is fiddling around doing mental calculations to arrive at a pointless figure but instead put all your concentration into flying the plane!

Pace

[foxmoth]

With the correct (standard?) equipment fitted in the tower, the cross wind is displayed on the same screen as the current "instant" wind, the 2 minute wind, the 10 minute wind, and maximum gust within a similar time period but I forget whether its 2 or 10 minutes.

Whilst this may be fitted at some fields it is certainly not the case at all, many I know just have direction and speed, not sure How common this kit is, but certainly not (standard)!

[bubo]

Am I the only one who doesn't caclulate cross wind component? I am usually accepting the info with comment to my self "from the left" or "a bit stronger from the rigth" but i do not recall calculating 4.6 kts from left. And 4 kts of of 25 wind is not the same as 4kts wind at 90 deg to the runway.

[aluminium persuader]

If you can't land without ATC supplying a crosswind component for you, are you never going to fly into or out of an uncontrolled airfield? Are you never going to have to make a forced landing?

A lot of ATC units don't have the equipment to display the resolved winds and, given that wind is a continuously variable fluid, would have to spend all their time doing maths instead of controlling aircraft. We could always slow down the movement rate to one take-off or landing every 5 mins or so, I suppose, to give us the time?

Try spending some time taking random winds & resolving them in your head, hen doing the maths & seeing how close you are. You will get better with practice. There are also various accessories (eg flight rulers, fwizz-wheels etc) with basic resolution charts printed on them, and I can recommend the RAF Flight Information Publication (FLIP) to you - loads of conversion charts, climb/descent gradients, wind resolution charts, flight-planning & emergency info. It's a little yellow book that doesn't at all mind being bent out of shape & being stuffed into a flight-bag!

[MichaelJP59]

I certainly don't bother calculating it, most of the time a combination of looking at the windsock and once you are actually on final, your crab angle. I transition to wing down but always start with a crab as that gives you a good idea.

Its not exactly a precision science anyway, the measured wind will not be the same as the wind you actually experience on your way down final, its measured in a different place and a short time before you will be landing.

[Johnm]

At that stage of the landing I'd be either watching the ILS display or looking at the runway and lining the aircraft up accordingly. If the attitude of the aircraft is then really scary don't land.

[mm_flynn]

The only time I remember calculating X-wind component was on a trip to Inishmore where it was blowing a gale (as usual I guess). I had made a decision/agreement with my Ops Department (aka wife) that we would not attempt the landing with more than 20knots cross wind. I found it a very useful process to help keep the landing decision objective. I also managed to land the Bonanza in about 150 m - just past the turnoff (my shortest ever Bonanza landing).

[VP-F__]

I have always preferred landing wing down in a crosswind assuming the aircraft allows. If you cannot hold the centre line with the wing down at very short finals then the wind is obviously too strong. I guess one reason that ATC might not give a xwind component is because of the variety of traffic they deal with. A vintage taildragger might have a 10 kt crosswind limit compared to something else with a 30kt limit. It is more info than needs to be given and radio time that doesn't need to be taken up. As others have said if you are competent enough to fly an aeroplane then it is not a difficult job to work out the component.

[peterh337]

The answer to the OP is that the line on what ATC is expected to deliver has to be drawn somewhere, and this is where it is drawn :)

Delivering the actual wind (in degrees magnetic) on final is what they do. This happens to correspond to the way wind is presented in tafs and metars (but there it is in degrees true).

If ATC handed out the c/w component, you would not know what any headwind or tailwind component was unless they gave you that as well, and that impinges on other obligations they have e.g. specifying a "gust" when the actual wind velocity exceeds X knots, etc. You might have a "gust" on the headwind and have no "gust" on the crosswind, if their values happened to lie either side of X :) And headwind is important because if it is say 40kt then you can expect an impressive amount of wind shear ;)

[dont overfil]

This seems a very simplistic view on what the wind does.

In the real world the air is fluid, changing constantly. All the tower can do is give you an average and perhaps a late update.

Furthermore the wind at the tower can differ from the wind at the threshold.

In fact at a couple of nearby fields to me if the wind is northerly the windsocks at either end of the runway can be seen pointing opposite directions.

D.O.

[englishal]

I just look at the windsock.

[Human Factor]

Quote:
Luckily there's an easy way to work it out, close enough anyway. You don't need any fancy charts, computers etc.

Suppose the wind is reported as 12 @ 350 and runway is 31.

First work out the relative bearing. RB = 350 - 31*10 = 40 degrees.

Now xwind component = wind speed * RB/60, i.e. 12 * 40/60 = 8. If RB is >60, then x-wind = wind speed.

This is as close as the reported winds are ever going to be accurate anyway, and dead easy to do in your head. Worst case error is about 15%.
Not sure about other people, but I found that a confusing explanation of the clock code I explained earlier - and in reality you only need the 15/20/30/40/45 degree off ones which are the easy ones to work out - anything below 15 degrees off is not normally worth worrying about, and above 45 degrees I would work out the 45 degree amount and estimate from there, knowing that at 60 degrees I am looking at full Xwind.

In short:

15 degrees off = 15/60 = 1/4 of windspeed is crosswind component
30 = 30/60 = 1/2
45 = 45/60 = 3/4
60 = 60/60 = all of it

Ask yourself, does it really matter if it's 29 degrees off or 31 for a fifteen knot crosswind?

If the demonstrated crosswind component for your aeroplane is more than the windspeed given, there's no need even to do the sum. Look out of the window, fly the aeroplane and if you're not happy go-around.

It works quite well for nav too using maximum drift rather than windspeed. :}

[yates]

With the correct (standard?) equipment fitted in the tower, the cross wind is displayed on the same screen as the current "instant" wind, the 2 minute wind, the 10 minute wind, and maximum gust within a similar time period but I forget whether its 2 or 10 minutes

Not fitted as standard at any ATC unit I know of in the UK.
Calculating the crosswind component is entirely the pilots responsibility, we've got enough to do as it is (calculating the solution to 8 down and 9 across, finishing off the last custard cream and occasionally attending to aircraft....;)).

[foxmoth]

15 degrees off = 15/60 = 1/4 of windspeed is crosswind component
30 = 30/60 = 1/2
45 = 45/60 = 3/4
60 = 60/60 = all of it

Ask yourself, does it really matter if it's 29 degrees off or 31 for a fifteen knot crosswind?

Exactly - that's why I quoted the ones I did! I included the 20 and 40 ones because they are also really easy to work out being 1/3 and 2/3 - can be easier if you have say a 15kt wind - and if it is 14 or 16kts then I would take it at 15 if say 40 degrees off. No arguments about applying it to Max Drift, just did not want to add further complications in.:}

[aluminium persuader]

Yates, It's been standard kit in UK mil towers for at least the last 15yrs, but I don't recall seeing it in a civvy tower.

8 down is "gnu" and 9 across is "paradox". Put the custard cream down & stick to the chocolate digestives! :ok:

[spekesoftly]

Vaisala displays, installed in a number of UK civil ATSUs, can be user switched between max / min and cross / tail.

http://www.vaisala.com/Vaisala%20Documents/Brochures%20and%20Datasheets/WIND50%20B210702EN-A.pdf

[GeeWhizz]

Calculating the crosswind component is entirely the pilots responsibility


Agreed. But I can never be bothered to work out the crosswind. All I need to know is whether it's significant and if so whether left or right by a little or a lot, the aeroplane will do the rest. :}

[Pace]

Sometimes Armchair discussions loose what happens in reality? On really strong wind days ATC will call winds on final a number of times to help you get a feel for whats happening on the ground.
They do this not expecting a reply from the pilot.

" 240 15 ! 260 30! 230 10! 270 30 etc" What are you supposed to do with your calculator bouncing around cracking your head on the roof?
What are they supposed to do add the changing crosswind component on every call? Get real fly the plane not the calculator or the armchair :E

Pace

[thing]

You'll know if the crosswind is a bit iffy 'cos the wheels will come off when you land. Always a good pointer I think.

You'll be standing there scratching your head at the three stubs at the bottom of the fuselage. It won't be an undercarriage, it will be a tripod.

[Genghis the Engineer]

Coming late to the discussion - I actually think it's a good idea. With a lot of hours I can handle the mental arithmetic - but when I had maybe a few hundred hours, or was unable to fly more than 20 or so hours per year, I really was not sharp enough to do those calculations quickly and reliably during an approach and landing, when I really was working bloody hard.

Let's say I was landing on runway 24, and the wind was 300/15.

To say "Wind three hundred degrees at one five knots" takes about 3 seconds (I just timed it).

Inventing some phraseology, to say "Headwind zero eight, Crosswind one two right" takes about the same time. It's the same information, but already interpreted.


As for ATC having to work it out? Sorry, but we're in the 21st century - any halfway competent IT geek could make a machine to display that information from the anemometer readout in a couple of quiet afternoons.


So yes, I think it's a fair question - crosswind (and head/tailwind) data could be calculated continuously and automatically, and given on RT in the same time, reducing the mental workload of a pilot who may well already be working fairly hard. Automation would eliminate additional ATC workload, and there's nothing to stop the more conventional wind information still being available on ATIS or on request.

G

[Maoraigh1]

I'm never that interested in the figures. It's too scary to know the detail, makes you worry. I just look at the sock
On very short final, I just look at the runway, and the bank angle to stay lined up. The wind direction may (speed will) be different from what the anemometer indicates.

[foxmoth]

As already said, the wind is constantly changing, so for limits it should have been worked out well in advance, once on finals it it really a case of looking at what drift you have offset and saying "am I comfortable with this" - if not, Go Around!

[spekesoftly]

As for ATC having to work it out? Sorry, but we're in the 21st century - any halfway competent IT geek could make a machine to display that information from the anemometer readout in a couple of quiet afternoons.They already have, please see post #27. Pressing the SET button in the photo (see link) changes the Max and Min wind displays (top left and right) to show the crosswind and tailwind components.

[Pace]

So yes, I think it's a fair question - crosswind (and head/tailwind) data could be calculated continuously and automatically, and given on RT in the same time, reducing the mental workload of a pilot who may well already be working fairly hard. Automation would eliminate additional ATC workload, and there's nothing to stop the more conventional wind information still being available on ATIS or on request.

Genghis

Cross wind component is rarely static. Lets look at the situation where ATC are calling out winds for your information as I posted above 220/15 240/30 270/35 200/10.
You have given yourself a crosswind limit of say 15 kts ?
Now I can land ? Now I cant? Now I cant ? now I can?
Its the big picture, your ability and the aircraft limits not the demonstrated limits. What is the windshear like? How constant is the wind and its direction ?
These are all questions which determine whether you chuck away the approach and go elsewhere.

Pace

[Pilot DAR]

I think that expressing crosswinds as a numeric value has merit, but not to the point of really worrying about on short final. It's kinda like buying a Rolls Royce, if you have to ask "how much?", you can't afford it.

Knowing the wind direction and intensity is obvioulsy worthwhile, as it helps you to make a decision to land at that airport. Once on final, if in doubt, simply ask yourself if you are able to track perfectly down the final approach. If you cannot fly final on the runway heading, chances are that landing there might exceed your skill.

As mentioned, the crosswind value for any certified aircraft is not legally limiting. It is a guidance for your judgement, and a demonstration that the aircraft met the certification requirements. Often times, the aircraft is easily capable of much larger crosswinds, but the manufacturer did not wish to declare that - they just stated the minimum required. This is evident in that many pilots land in much stronger crosswinds with no difficulty.

What's going to challenge you will be the instantanious variations in wind direction or intensity. On Friday I approached to land with the surface wind reported as "5 to 10 knots, variable from 030 to 170 degrees". The runway choices were 18 or 36. The 10 knot crosswind would be no problem, but the variation can make it really interesting!

On the other hand, I did crosswind testing in a modified Cessna Caravan, with a direct 25 knot crosswind. Aside from reaching full rudder travel a few times on the runway, it was really quite easy, as the wind was very steady.

Like many things with flying light aircraft flying, it's probably better to simply look out the windshield and fly, rather than concentrate on numbers.....

[Pace]

If you cannot fly final on the runway heading, chances are that landing there might exceed your skill.


As Pilot Dar points out if there is enough control authority to maintain the centreline on approach chances are there is enough control authority to handle a landing.
It is rare that surface winds are stronger than approach winds. They maybe slightly different in direction and prone to terrain and obstruction influence but chances are the above criteria is a good indication.

As for the pilots ability that is another question.

Pace

[Genghis the Engineer]

Cross wind component is rarely static. Lets look at the situation where ATC are calling out winds for your information as I posted above 220/15 240/30 270/35 200/10.
You have given yourself a crosswind limit of say 15 kts ?
Now I can land ? Now I cant? Now I cant ? now I can?

But that doesn't change however the winds are given to the pilot. I'm only suggesting doing it in a manner which reduces the pilot's mental workload a little.

G