A windy question this time
Thread Starter
Joined: May 2000
Posts: 326
Likes: 1
From: UK mainly
A windy question this time
I was on the approach the other day coming into land the tower gave me a w/v 180/10kts. I looked at the wind sock and it was more like 210 ten kts. My student says the following......Here is my brain teaser....If the wind is given in magnetic (unlike a forecast) and the wind comes relative to TRUE NORTH (because the wind doesn't "feel" the effects of variation) and the controllers equipment makes a correction for local variation which means the windsock tells a true picture and the given w/v is different then what is going on..????
i have a handful of these types of quezzies I don't dare say this one to my colleagues for fear of intense laughter!
PS here in FAGG the variation is 25w
Last edited by dynamite dean; 6th April 2002 at 10:42.
Joined: Oct 1999
Posts: 343
Likes: 2
From: UK
You're not winding us up are you???
When you say it looked more like 210° I guess that was relative either to your heading or to the runway - both of which are measured in MAGNETIC. So both the tower wind and your interpretation of the windsock were relative to magnetic north.
Why the difference? could be lots of things like: knackered equipment in the tower; terrain shielding near the windsock; funneling of the wind etc etc.
At Gibralter it is no uncommon to see the windsocks at each end of the runway pointing in opposite directions. I've seen it elsewhere on a calm, hot day when a thermal forms in the middle of the airfield and everything is being sucked into it.
When you say it looked more like 210° I guess that was relative either to your heading or to the runway - both of which are measured in MAGNETIC. So both the tower wind and your interpretation of the windsock were relative to magnetic north.
Why the difference? could be lots of things like: knackered equipment in the tower; terrain shielding near the windsock; funneling of the wind etc etc.
At Gibralter it is no uncommon to see the windsocks at each end of the runway pointing in opposite directions. I've seen it elsewhere on a calm, hot day when a thermal forms in the middle of the airfield and everything is being sucked into it.
still learning....
Joined: Jul 1999
Posts: 169
Likes: 0
From: USA
Another reason may be local procedures. Our tower has readouts for 3 minute average or instantaneous.
If the winds are variable (which they always are to some degree), the verbal and the windsock may very well be 30 degrees different. Local control always give winds in magnetic. The winsock always gives relative.
If the winds are variable (which they always are to some degree), the verbal and the windsock may very well be 30 degrees different. Local control always give winds in magnetic. The winsock always gives relative.
Joined: Dec 2000
Posts: 38
Likes: 0
From: On top of the world!
I didn't meen that to be forecast, I meant metreport. At BIAR, one runway, here in Iceland on a few ocations the wind bag at one end is pointing one direction and the windbag at the other end is pointing quite the opposite. Just the landscape around I guess.
Joined: Aug 2001
Posts: 144
Likes: 0
From: At home
dd - no the water still spirals down into the plughole - only it does not always turn to the right as in the northern hemisphere or to the left as in the southern hemisphere - it will go either way depending on the initial movement of the bathwater relative to the orifice. In a truly random universe 50% of your baths will end with clockwise vortex and 50% with an anti-clockwise vortex down your plughole at the equator. Even in the northern hemisphere you can get a clockwise vortex if you give the bathwater the necessary stimulus by stirring it in the right direction to get it started. Isn't this a gloriously pointless thread?
Joined: Aug 1998
Aviation Qualifications: ATPL
Posts: 6,623
Likes: 847
From: Ex-pat Aussie in the UK
I saw an article on a travel show once about a place in
Africa on the Equator, where the locals had set up a tourist "event". They would take a few dollars from a tourist to show the water swirling in different directions down a plastic funnel a hundred meters or so either side of the Equator! Gotta love capitalism at work - all slight of hand of course.
Africa on the Equator, where the locals had set up a tourist "event". They would take a few dollars from a tourist to show the water swirling in different directions down a plastic funnel a hundred meters or so either side of the Equator! Gotta love capitalism at work - all slight of hand of course.
Joined: Jun 2000
Aviation Qualifications: ATCO
Posts: 271
Likes: 23
From: LONDON England
Reminds me of a story about a Shorts Belfast (I think)that landed in Anchorage a few years back.
The crew taxied in and disembarked the aircraft.A few days later they returned to the aircraft to find the rudder damaged.On enquiring with ATC what
had happened and that they had parked into wind according to the windsock,the reply recieved was
"Oh you don't take any notice of the windsock,it's been frozen solid for months!!"
Cheers
autothrottle
The crew taxied in and disembarked the aircraft.A few days later they returned to the aircraft to find the rudder damaged.On enquiring with ATC what
had happened and that they had parked into wind according to the windsock,the reply recieved was
"Oh you don't take any notice of the windsock,it's been frozen solid for months!!"
Cheers
autothrottle
