Passing winds
 

All,

I am interested in what winds Tower controllers use when giving wind checks to arrivals and/or departures, either routinely or when the conditions are different to the ATIS?

Is it the instantaneous wind ? If so, what are the parameters for this (over what period is this measured)?

Is it the mean wind? If so, again what are the parameters for this (over what period is this measured)?

Can anyone explain the difference between a gust and a peak wind? Are the same thing?

In the UK we pass the 2 minute average wind.

We can give the instant wind if we think it appropriate, or if asked, but we have to preface it: "Instant wind 020 10kts" to make it clear to the crews which wind they're hearing.

Gonzo.

An instantaneous wind is just that, the wind at that instant. As Gonzo said, we usually use the 2 min average unless sepcifically asked for an instantaneous reading. We use a 10 min average for the METAR report, which goes out on the ATIS.

A gust is defined by the Met. Office as a maximum wind speed over the corresponding 10 mins which exceeds the mean by 10 kts or more. Don't think I've seen a definition (in the UK) of a peak wind


----------------------
VA
www.stevelevien.com

....... and if it is passed by ATC it should already have magnetic variation applied.

Many years ago I used to operate into a northern UK airfield and I am convinced that the controller (who was also involved in management) used to pass wind checks appropriate to aircraft type. I recall one occasion in particular when, on announcing that I was diverting, the crosswind instaneously dropped to precisely the limiting speed for my type. Having landed virtually sideways on that occasion, I have often wondered the accuracy of his wind checks!

I can't believe there have been 4 replies so far, and all of them serious.
Isn't this just THE most appropriate smiley:8 ?

I know my cat has a problem with wind, but I didn't know she could use my computer!

I once requested a wind check on finals (I was pretty convinced the crosswind was beyond me) and got a series of instant winds, e.g.

Wind 060 at 18, 070 at 15, 060 at 18, 050 at 20

until short finals. These were presumably instant winds, and were very useful (i.e. I promptly went around and asked for a different runway!).

Tim

:p when passing wind, I always try to relax my cheek muscles, I find this gives the best results. ;)

There, I've said it:D .

Ahem.

The "2 minute average wind" presumably requires some technology to provide the figure. While this may be available at the larger airfields, how about my local flying club?

Instantaneous only?

Eyes

If your local flying club is at an airfield will full ATC then they are required to comply with CAP670 ATS Requirements. This in turn, with wind instruments, requires compliance with ICAO Annex 3 Meteorology if there are 'schedule journeys' by aircraft over 5,700 kgs although I think it is set to apply to all aerodromes with ATC soon. I assume Annex 3 mentions the two minute average.

Pause for breath. :confused:

If your airfield is FISO then they are recommend to comply with CAP670. If A/G then not. You might find that many do anyway, the only way to find out is to go and ask. :D

For the terminally bored, the reference is CAP670 ATC01 Annex A.


VA

thanks so far, I thought I'd go for a cheeky title (pun intended) go coax some responses and with 274 looks so far, not a bad return.

Vintage, I'm interested in the 10 minute average that you use for the Metar, I gather your equipment does this for you, am I correct?

And how does a pilot know that I am giving a 2 minute average wind? Is this buried deep within an ICAO doc somewhere?

...cocking a leg works for me....

:ok:

My equipment is second-to-none, but, yes, the Vaisala wind instruments we have does this for us.

The use of the 10 min and 2 min average is an ICAO SARP and contained in Annex 3, para 4.5.5.

VA

In a past life when I was errr 'younger' and based at a very northern UK airfield,

Wind gusting over 70Kt, at the start of an ACR430 half-mile SRA,
“Eight miles, check wheels, surface wind 300 56kt gusting 74kt, I will continue to pass wind though out the approach” !!!
:O

Ahhhh, the ACR430 . . . . . I remember it well. Did over 500 half-mile approaches on it. RIP.


VA

........ and how many of us altered the beam elevation in a vain attempt to get rid of conflictors?

We could always wax lyrical about how we "progressed" onto the AR1, but then that would be another story................

go-rounder, you mentioned a situation where the surface wind was "300 56kt gusting 74kt". How were you determining the gust, was this from the instantaneous or the peak wind?

ACR 430
 

G-A , I hope you didn't operate the 430 outside the max wind limit, or maybe you had protection. The older 424 used to do funny things in high wind and I wouldn't dare use even a 430 to provide a serious SRA with that wind. I award you the Air Traffic Hero Medal for one week only, after which it will be re-assigned.

Missy
In them days it was two dial's direction and instant wind speed readout, you had to remember the gusts and guess the average!

055166k
Ooooow always protected, we are talking Sumburgh here so if it wasn’t protected it wouldn’t have been there very long! Record when I was there was 93kt gusts with sustained over 70kt! I think the 430 was given to Albania for further use after the ILS went in.
:D

surface wind updates
 

What is the official criteria for passing the updates of surface wind to an aircraft on final?

A point can be reached where they become distracting when the latest update is already within the existing band already passed.

I am not talking about an update which is a significant change to that passed in say the last two minutes.

ecj, there's no real definitive answer. I don't have the books to hand but they say something like wind with landing clearance and more if the pilot requests them (instantaneous or otherwise). Many controllers use common sense and pass more reports if the wind is all over the place.

If they're a nuisance all you have to say is "no further windchecks" or something along those lines. Not that I've ever seen it of course ;) , but I have heard that some pilots ask for windchecks down final until they hear one that's inside limits and then say "no more thanks"

Pull the cabin air knob first ... :)

Page GEN 3-5-5 et seq in the UK-AIP lists which airfields pass Average winds and which pass Instant winds.

Whilst my main occupation is as an instructor I work part time as a FISO and the equipment which we have available is only capable of providing Instant winds. If the wind is changing direction significantly or varying markedly in strength, but not at the moment when I pass the wind information to the pilot then I will pass the information as “ the wind is instant xxx at yy knots, within the last x minutes the wind has been variable xxx to yyy, aa gusting bb knots”, otherwise I pass the wind information without stating that the value is an Instant reading.