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]

Originally Posted by SEP flyer

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]

do you really calculate cross wind component?

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