Wind on departure?
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Wind on departure?
For those of you working in a tower or pilots,
Do all towers include surfacewind when issuing the take-off clearance?
ie "wind 240degress 10 knots rwy18 cleared take-off"
Do all towers include surfacewind when issuing the take-off clearance?
ie "wind 240degress 10 knots rwy18 cleared take-off"
Last edited by Somewhere In Time; 12th Jun 2009 at 08:08.
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Good question.
The books would appear to indicate that you do not need to pass the wind although I'm not sure if there are many Uk airfields who do not pass it with the take off clearance.
Reference
CAP413 Chapter 4 1.7.2
Take Off Clearance
Controllers will use the following phraseology for take off
G-CD cleared for take off
**The surface wind will be passed if there is a significant difference to that already passed.
From the above then, assuming that the ATIS letter hasn't changed from that given at start up, is it necessary to pass the surface wind to departing traffic as there has been no significant change to the wind given on the ATIS?
CAP493 also gives the option of a simple "cleared for take off" in it's phraseology section with the condition that an instant wind will be given to the pilot if requested.
The books would appear to indicate that you do not need to pass the wind although I'm not sure if there are many Uk airfields who do not pass it with the take off clearance.
Reference
CAP413 Chapter 4 1.7.2
Take Off Clearance
Controllers will use the following phraseology for take off
G-CD cleared for take off
**The surface wind will be passed if there is a significant difference to that already passed.
From the above then, assuming that the ATIS letter hasn't changed from that given at start up, is it necessary to pass the surface wind to departing traffic as there has been no significant change to the wind given on the ATIS?
CAP493 also gives the option of a simple "cleared for take off" in it's phraseology section with the condition that an instant wind will be given to the pilot if requested.
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ICAO Doc 4444 says (relevant bits only):
Hope this helps....
7.3.1.2.1 Prior to taxiing for take-off, aircraft shall be advised of the following elements of information, in the order listed, with the exception of such elements which it is known the aircraft has already received:
b) the surface wind direction and speed, including significant
variations therefrom;
7.3.1.2.2 Prior to take-off aircraft shall be advised of:
a) any significant changes in the surface wind direction and speed, the air temperature, and the visibility or RVR value(s) given in accordance with 7.3.1.2.1.
b) the surface wind direction and speed, including significant
variations therefrom;
7.3.1.2.2 Prior to take-off aircraft shall be advised of:
a) any significant changes in the surface wind direction and speed, the air temperature, and the visibility or RVR value(s) given in accordance with 7.3.1.2.1.
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I agree. Windcheck only when it varies significantly from what is advertised or the pilot asks for it. Otherwise, why bother having an ATIS? Same with landing clearance.
Cheers,
NFR.
Cheers,
NFR.
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The ATIS can only offer a mean wind, whereas the Take-Off Clearance will generally provide an instantaneous wind.
JD
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The statistical answer to the question has to be ""No" - however the vast majority of professional ATCOs will provide it, as it is simply good airmanship ...
The ATIS can only offer a mean wind, whereas the Take-Off Clearance will generally provide an instantaneous wind.
The ATIS can only offer a mean wind, whereas the Take-Off Clearance will generally provide an instantaneous wind.
Cheers,
NFR.
There was a film on TV about 15 years ago dealing with New York's airports where I noted that surface wind was NOT given to departures.
What you must bear in mind is that the wind on ATIS will be a 10 minute average, but the wind passed by ATC will be a 2 min avge or instant so it will almost always be different from the ATIS.
What you must bear in mind is that the wind on ATIS will be a 10 minute average, but the wind passed by ATC will be a 2 min avge or instant so it will almost always be different from the ATIS.
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Thank you for all your replies gentlemen!
Yes, the book says that only significant changes should be stated. My question would then be; How much does the wind have to vary? 10degress and 5kts? Where is this stated?
And, how do you make sure that the information the pilot has is the latest? The ATIS the pilot has confirmed received might be outdated by the time he gets to the holdingpoint for departure and Im sure that most of the towercontrollers have other things to do than to update pilots on what Atis is valid.
Just seems like the easiest procedure would be to include wind with the take-off clearance.
Yes, the book says that only significant changes should be stated. My question would then be; How much does the wind have to vary? 10degress and 5kts? Where is this stated?
And, how do you make sure that the information the pilot has is the latest? The ATIS the pilot has confirmed received might be outdated by the time he gets to the holdingpoint for departure and Im sure that most of the towercontrollers have other things to do than to update pilots on what Atis is valid.
Just seems like the easiest procedure would be to include wind with the take-off clearance.
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ICAO Doc 4444 para 7.4.1.2.2 states that before takeoff an aircraft shall be provided any significant changes to the wind that was provided prior to taxi (ie, on the ATIS). I'm trying to locate what 'significant' means, but I am sure I have read 5 knots and 10 degrees somewhere. Will keep hunting.....
Oh, and if the ATIS is changed while an aircraft is taxiing, the above provisions must be used, as an ATIS change is made because the comditions have changed. The tower or ground controller will most definitely pass the new info on to pilots - it is essential to their operations.
However, passing the wind on departure for the sake of it is not essential - why not pass the temp and QNH too then? I know, because they haven't changed and if they have, they will be passed. The wind is no different.
Cheers,
NFR.
Oh, and if the ATIS is changed while an aircraft is taxiing, the above provisions must be used, as an ATIS change is made because the comditions have changed. The tower or ground controller will most definitely pass the new info on to pilots - it is essential to their operations.
However, passing the wind on departure for the sake of it is not essential - why not pass the temp and QNH too then? I know, because they haven't changed and if they have, they will be passed. The wind is no different.
Cheers,
NFR.
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If you look at it from a logical point of view , as has already been stated, the SW on the ATIS would be the ten minute average. whereas the wind passed to pilots would be the two minute or Instant wind (if asked for by the pilot or deemed necessary by the ATCO)
.
If one adopted the "only if it varies significantly principal "
I would have to firstly check the actual reading ,
THEN, compare it to the wind speed and direction given on the ATIS ,
THEN, compare the two readings ,
THEN, establish if the difference is considered significant
THEN ,if it is ,Pass it to the A/c along with take off clearance.
At the moment dare I say, the convention is
Cleared take off ( rwy if necessary) surface wind XXX degrees YY kts.
I believe the degrees and kts can be dropped
One simple action against against five.
As for passing the QNH if it had changed I have to
and the TEMP if it went through 25C then again I would.
.
If one adopted the "only if it varies significantly principal "
I would have to firstly check the actual reading ,
THEN, compare it to the wind speed and direction given on the ATIS ,
THEN, compare the two readings ,
THEN, establish if the difference is considered significant
THEN ,if it is ,Pass it to the A/c along with take off clearance.
At the moment dare I say, the convention is
Cleared take off ( rwy if necessary) surface wind XXX degrees YY kts.
I believe the degrees and kts can be dropped
One simple action against against five.
As for passing the QNH if it had changed I have to
and the TEMP if it went through 25C then again I would.
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I would have to firstly check the actual reading ,
THEN, compare it to the wind speed and direction given on the ATIS ,
THEN, compare the two readings ,
THEN, establish if the difference is considered significant
THEN, compare it to the wind speed and direction given on the ATIS ,
THEN, compare the two readings ,
THEN, establish if the difference is considered significant
Honestly, your '5 actions versus 1' isn't that difficult - you would have to look at the wind reading and pass it to the aircraft anyway. I was always taught that the wind instrument check should be part of your scan when issuing takeoff clearances anyway - and simple mental calculations of +/- 10degrees or 5 knots, well, are simple.
Sorry, have to disagree with you on this one. The book (and my logic) says required only when significant, but there's nothing stopping you passing it all the time.
Cheers,
NFR.
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I was always taught that the wind instrument check should be part of your scan when issuing takeoff clearances anyway - and simple mental calculations of +/- 10degrees or 5 knots, well, are simple.
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Better to give the up to date 2 min average magnetic wind on departure than the old 10 min average true bearing. Yes I know the ATIS wind and can work out whether there's a significant change but why bother performing that calculation up to thirty times an hour?
We're too busy for that and I normally have plenty of better uses for that thinking time.
A superfluous wind check is far less superfluous than "bye-bye" and "good-day" and all that stuff.
The wind is a more dynamic quantity than temp or QNH and changes more rapidly - it's a good habit to give it all the time.
If you're not in the habit, the one time you get distracted and fail to pass on a significant change may be the one time it'll feature in an incident report.
We're too busy for that and I normally have plenty of better uses for that thinking time.
A superfluous wind check is far less superfluous than "bye-bye" and "good-day" and all that stuff.
The wind is a more dynamic quantity than temp or QNH and changes more rapidly - it's a good habit to give it all the time.
If you're not in the habit, the one time you get distracted and fail to pass on a significant change may be the one time it'll feature in an incident report.
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How do you know that the pilot has the current ATIS? Most of them are at least a couple behind, especially when the weather is poor, and does the tower check what letter every inbound has because it can't be part of your scan as it's been passed to approach. Oh and our departure strips don't display what ATIS letter the pilot has anyway.
Just give the wind.
Just give the wind.
