Windsock?

[NT5224]

Hi folks!

 

A couple of quick questions about windsocks.

 

In this age of instant online weather information, remote weather cameras and other technologies there's something satisfyingly low-tech about a windsock! No doubt  back in the day, the Wright brothers hoisted something similar to flap around for them on the blustery beach at Kittyhawk.

 

First question: Is there anything in the regs about windsock placement on an airfield? I can't recall ever seeing anything written. Should it be midfield  or at an end of the strip. Should it be adjacent to apron hangar and tiedowns? Or is it totally discretionary?

 

Next question. You blokes with your own strips (say farm strips or small airfields). What size of windsock do you recommend?    8ft or 12ft? I wouldn't go less than 8ft if its got to be seen from 1000ft. Any views on this?

 

Also is there any difference between a regular white sock and a yellow one? Is one more visible than the other? Which would make a better colour?  Opinions please.

 

cheers

 

Alan

 

 

[Yenn]

The white sock is the primary one. There can be more than one yellow socks. Eight foot is a good size, you are mainly looking at it from about 1500' and having a dark background under the sock helps.

 

 

[KRviator]

For your bedtime reading, may I present Section 8.7 of the Part 139 MOS...Which  - because not everyone understands CAsA - is simply windsock standards from the aerodrome standards manual. The stuff in red is what you need. OF course, if you are only using it yourself, I'd probably go one of the US red-and-white ones that you can use to gauge wind strength as well,...

 

Section 8.7: Wind Direction Indicators

8.7.1 Requirements

8.7.1.1 CASR Part 139 requires the aerodrome operator to install and maintain at least one wind direction indicator at the aerodrome. CASA may issue directions requiring additional wind direction indicators to be provided.

8.7.1.2 CASR Part 139 also requires that non-precision approach runways be provided with a wind direction indicator at the threshold of the runway. However, subject to paragraph 8.7.1.3, for runways 1200m or less in length one centrally located wind direction indicator visible from both approaches and the aircraft parking area is acceptable.

8.7.1.3 Paragraph 8.7.1.2 does not apply to a runway if surface wind information is passed to the pilots of aircraft approaching the runway through:

(a) an automatic weather observing system that:

(i) is compatible with the Bureau of Meteorology weather observing system, and

(ii) provides surface wind information through an aerodrome weather information broadcast, or

(b) an approved observer having a communication link with pilots through which timely information about surface wind may be clearly passed to them; or

© any other approved means of providing surface wind information.

8.7.1.4 A wind direction indicator must be located so as to be visible from aircraft that are in flight or aircraft that are on the movement area.

8.7.1.5 A wind direction indicator must be located so as to be free from the effects of air disturbance caused by buildings or other structures.

8.7.1.6 A wind direction indicator provided at the threshold of a runway must be located:

(a) except if it is not practicable to do so, on the left hand side of the runway as seen from a landing aircraft; and

(b) outside the runway strip; and

© clear of the transitional obstacle limitation surface.

8.7.1.7 If practicable to do so, a wind direction indicator provided at the threshold of a runway must be located 100 metres upwind of the threshold. 

 

8.7.2 Standards

8.7.2.1 A wind direction indicator must consist of a tapering fabric sleeve attached to a pole at its wide end 6.5 m above the ground.

8.7.2.2 The sleeve must be 3.65 m long and taper from 900 millimetres in diameter to 250 millimetres in diameter.

8.7.2.3 The wide end must be mounted on a rigid frame to keep the end of the sleeve open and attached to the pole so as to allow it to move around freely.

8.7.2.4 The fabric of the primary wind direction indicator must be white and that of any additional wind direction indicator must be:

(a) yellow; if it is not intended to be illuminated at night; or

(b) if it is intended to be illuminated at night; either white, or another colour that is clearly visible when illuminated.

Note: Natural or synthetic fibres having weight range of at least 270 to 275 g/m2 have been used effectively as wind indicator sleeve material.

8.7.2.5 The primary wind direction indicator must be located in the centre of a circle 15 m in diameter, coloured black and bordered:

(a) by a white perimeter 1.2 m wide; or

(b) by a ring of 15 equally spaced white markers each with a base not less than 0.75 m in diameter.

Figure 8.7-1: Wind Direction Indicator

8.7.2.6 For the illumination of wind direction indicators see Chapter 9.

 

Section 8.8: Ground Signals

8.8.1 Signal Areas

8.8.1.1 A signal area must be:

(a) 9 metres in diameter;

(b) black,

© bordered by:

(i) a white border 1 metre wide; or

(ii) 6 equally spaced white markers, each with a base not less than 0.75 m in diameter; and

(d) not more than 15 m from the wind direction indicator, or, if applicable, the primary wind direction indicator. The primary wind direction indicator is located closest to the apron of the aerodrome.

Figure 8.8-1: Signal Area

 

8.8.2 Ground Signals in Signal Area

8.8.2.1 A ‘total unserviceability’ signal must be displayed in a signal area when an aerodrome is closed to landing aircraft.

8.8.2.2 A ‘total unserviceability’ signal must consist of 2 white strips not less than 0.9 m wide and 6 m long, bisecting each other at right angles.

9m9m1mWhiteWhiteBlackBlack

 

8.8.2.3 A ‘restricted operations’ signal must be displayed in the signal area at an aerodrome with more than one type of surface on its movement area, if aircraft are only to use:

(a) the sealed runways, taxiways and aprons; or

(b) the gravel runways; where there are no sealed runways, taxiways and aprons.

8.8.2.4 For the purposes of Paragraph 8.8.2.3:

(a) a sealed runway, taxiway or apron is one whose surface is wholly or mainly sealed; and

(b) a gravel runway, taxiway or apron is one whose surface is wholly or mainly gravel.

© the ‘restricted operations’ signal must consist of 2 white circles 1.5 m in diameter, connected by a white cross bar 1.5 m long and 0.4 m wide.

(d) a ‘glider operations’ signal, must consist of a white strip 5 m long and 0.4 m wide crossed at right angles by 2 strips 0.4 m wide and 2.5 m long, each being 1.05 m from the closest end of the horizontal strip, as shown below.

Figure 8.8-2: Total unserviceability signal

2.55m0.9m2.55m2.55m2.55m0.9mWhite

 

Figure 8.8-3: Restricted operations signal

 

Figure 8.8-4: Glider operations signal

0.4m

1.5m

1.5m

White

0.4m 2.5m

0.4m

5.0m

2.1m

White

Authorised Version F2017C00087 registered 01/02/2017

Manual of Standards Part 139—

Aerodromes

Chapter 8:

Visual Aids Provided by Aerodrome Markings, Markers,

Signals and Signs

Version 1.14: January 2017 8-82

 

 

 

 

 

[facthunter]

Well, there you go, and it's pretty comprehensive. It's nice to get a confirmation on final that the wind is still showing that you have made the right decision  to land the way you are. Light and Variable can have a totally different reading 10 minutes later or at the other end, especially if you are coastal when the sea breeze comes in, in the afternoon  around the time you are scheduled to land.  Nev

 

 

[rgmwa]

We have three windsocks at YSEN and it's not unusual for them to all be pointing in different directions!  I usually go with the majority decision, although when two of them at each end of a runway are pointing at each other, I toss a coin.

 

 

[kgwilson]

We only have 1 which is close to the threshhold of 1 runway adjacent to the taxiway & can be seen from the parking areas easily. If it was centrally located you wouldn't be able to see it from the parking area. It can be seen from both approaches but on the 08 approach you have no idea which way it is pointing till you land. Unless there is an already established runway you should always overfly at 1500 anyway, check the windsock & base your runway decision on that.

 

There is a theory that when the windsock is fully extended horizontally the wind is around 18-20 knots or more & 45 degrees to the ground 8-10 knots.

 

 

[old man emu]

We have three windsocks at YSEN 

 

Here we have a failure to use clear communication. The use of ICAO codes for airports might seem cool and show the writer to be Oh so groovy, but unless the reader is fully aware of that particular code, the message is not clear. It could have been written "At Serpentine, we ...", or "We have three ..."

 

Please resist using ICAO codes as shorthand in these posts. 

 

Old Man Emu

 

 

[old man emu]

I believe that this striped windsock is the type used in the USA. It obviously conveys more information than a plain white windsock, but our safety regulators know better,

 

8.7.2.4 The fabric of the primary wind direction indicator must be white 

 

 

Of course, some places are subject to higher wind speeds than others.

 

 

 

[rgmwa]

Here we have a failure to use clear communication. The use of ICAO codes for airports might seem cool and show the writer to be Oh so groovy, but unless the reader is fully aware of that particular code, the message is not clear. It could have been written "At Serpentine, we ...", or "We have three ..."

 

Please resist using ICAO codes as shorthand in these posts. 

 

Old Man Emu

 

Well, it's been a very long time since I thought of myself as cool and groovy - one look in the mirror is enough to destroy that illusion. However, I take your point OME, so Serpentine it is in future.  Sounds a lot nicer anyway!

 

 

[Old Koreelah]

I believe that this striped windsock is the type used in the USA. It obviously conveys more information than a plain white windsock, but our safety regulators know better,

 

8.7.2.4 The fabric of the primary wind direction indicator must be white 

 

 

Thanks for this, OME. Very clear, but this sort of precision requires the fabric weight and stiffness to be standardised. Our local windsock doesn't have "articulated" segments like this American one, so we must read it by the angle of the whole sock.

 

 

[old man emu]

 I take your point OME, so Serpentine it is in future.  Sounds a lot nicer anyway!

 

Thanks. You're nicer, too.

 

 

[old man emu]

Standards

 

 

 

Per FAA standards, a properly-functioning windsock will orient itself to a breeze of at least 3 knots (5.6 km/h; 3.5 mph) and will be fully extended by a wind of 15 knots (28 km/h; 17 mph).

 

 

Per Transport Canada standards: a 15-knot (28 km/h; 17 mph) wind will fully extend the wind sock, a 10-knot (19 km/h; 12 mph) wind will cause the wind sock to be 5° below the horizontal, a 6-knot (11 km/h; 6.9 mph) wind will cause the wind sock to be 30° below the horizontal.

 

 

[spacesailor]

I Do have to look those Ycodes up, when, I find the Old "2014 ERSA BOOK.

 

SPACESAILOR

 

 

[facthunter]

Life is too short to look up  "Y" codes. It really is a turn off.  Nev

 

 

[pmccarthy]

Socks come in at least two fabric weights and thus behave differently at different wind speeds.

 

 

[Matty]

When you buy one the manufacturer can tell you the speeds it indicates.

 

 

[old man emu]

This is the FAA Advisory Circular:

 

 FAA SPECIFICATION FOR WIND CONE ASSEMBLIES, AC No: 150/5345-27D

 

https://www.faa.gov/documentLibrary/media/advisory_circular/150-5345-27D/150_5345_27d.pdf

 

See Paragraph 3.2.3 for the specs for the fabric.