Airfield Control Tower: what do the numbers mean?

[Mark Harmsworth]

I am building the old Airfix Control Tower and am mildly confused by the numbers on top of the building.

 

This is it:

 

The number '23' is on large boards on both sides of the building and these are referred to as 'runway numbers'. This doesn't seem to make much sense to me as there would normally be two runways and why would only one number appear on the control tower. Perhaps the numbers were just to confuse the enemy?? Or . . . . .

 

I have tried searching and found some useful stuff. This for example: http://www.controltowers.co.uk/Site Map.htm but haven't got anywhere.

 

Any help appreciated.

Mark

 

 

[Scimitar F1]

Maybe runway in use? There would only be one and not all aircraft would have a radio.

[Army_Air_Force]

Most likely to inform crews on the ground which was the active runway. From the air, the 40ft square signals square would indicate the runway direction, surface condition, hazards and circuit direction for aircraft without radio. A similar sized square would have the airfield ID letters to identify the station.

[Sky dancer]

Hi,

 

It shows the runway in use. The number always refers to the magnetic heading of the runway. In the Airfix example, Runway 23 is on the heading 230°.

 

The runway heading is given to the nearest 10°, the last digit is always dropped. 

 

Each runway has two magnetic headings, in the Airfix example Runway 23 and Runway 05 - they are the same bit of real estate, just approached from different directions dependent on wind direction.

 

HTH.

[Graham Boak]

For the WW2 period, would normally be three runways on an RAF station, and four on an FAA station.  Each runway would have two numbers, indicating the compass direction.  Which runway was in use would depend upon the direction of the wind, as operations were into wind whenever possible.  So the sign 23 means land on runway 23, which is built on a line 230 degrees/50 degrees.  For interest, Heathrow was built with six runways, in three parallel pairs.

 

On a heavy bomber station normally one runway would be considerably longer than the others, and this would be used for normal operations except in strong crosswinds.  The longest runway on any airfield would be built in the direction of the prevailing winds.  Small aircraft like fighters would be more affected by cross-winds so would use the cross runways more often.  Aircraft on grass airfields would land/take off directly into wind, as indicated by the windsock and probably an indicator on the ground adjacent to the control tower.

[Scimitar F1]

19 hours ago, Sky dancer said:

The number always refers to the magnetic heading of the runway. In the Airfix example, Runway 23 is on the heading 230°.

Surprised that the magnetic not the true heading is used as magnetic headings vary all the time.

Edited September 4, 2020 by Scimitar F1

[71chally]

The number displayed on the board is the runway in use, it's the two figures of the degree number, the zero being removed.

It is based on magnetic heading, which does of course gradually change over time.  Once it goes over a certain point in degrees the runway gets renumbered.  For example St Mawgan was originally 14/32, then 13/31 and is now 12/30.

I believe it based on magnetic heading as easier to understand with a compass.

[Sky dancer]

Correct!

 

Which is why some runway headings, as marked on the runway threshold and any/all navigation publications, have to be altered occasionally if the magnetic heading changes sufficiently.

 

Airfield at which I flew most used Runway04/22. Changed to Runway 05/23 for a while, now back to Runway04/22..

[Graham Boak]

Such changes are small and infrequent: the movement of the Pole is more of interest to scientists than for everyday use.

[John B (Sc)]

3 hours ago, Scimitar F1 said:

Surprised that the magnetic not the true heading is used as magnetic headings vary all the time.

 

Until fairly recently there was no easy way to read true heading while airborne. Magnetic heading was available, via the compass, hence it was used. In fact at the time of WW2 times there was no easy way to determine true heading when ground borne either, as far as I know ! 

 

Once we got reliable inertial navigation systems, with North sensing gyros, true heading could be determined directly. Previously it had to be derived from magnetic. Many folk got lost - and some still do -  by confusing the two and how to convert  one to the other.

 

With GPS now readily available true headings are easily found - they are what a GPS will display by default.  There are still plenty ways to add confusion - which spheroid assumption is in use? - for example.

 

It's impressive how easy it is to get navigation wrong!  One friend of mine has made a very successful & profitable career helping people sort out and reduce their position finding errors. Very important for many purposes and largely misunderstood.

 

Edited September 4, 2020 by John B (Sc)

[Scimitar F1]

3 hours ago, Graham Boak said:

Such changes are small and infrequent: the movement of the Pole is more of interest to scientists than for everyday use.

You would be surprised - the variation is on the edge of every OS map and Nautical chart 

 

Mag to Grid - get rid! (as I was taught at Sandhurst)

[Black Knight]

May I add somat?

OS maps also have an issue code letter. 

When I set navigation rallies for my car club I need to specify which OS code letter map the competitors need to use as the magnetic variation noted on the maps can be different from issue to issue. Some of the rally's sections are done by compass bearing and more than one competitor has got totally lost as they did not use the correct map. I had one competitor who insisted on using a 10 year old map. We found him going round in circles in south County Armagh, well off the set route.

[Graham Boak]

I would not be the slightest surprised: but at any given time the variation is standard on a day-to-day basis.  particularly as there is already a + or - 5 degree allowance in the runway heading anyway.  Yes, it can vary over a 10 year period, but that itself exceeds the duration of WW2, and indeed probably the life of the paint used to make the heading on the runway.  (If it was there in wartime...)  And as the pilot flies by a magnetic compass, then the heading he is given to fly to has to be a magnetic heading.  Then he has to allow for crosswind - no-one claimed life was easy.

[Work In Progress]

19 hours ago, Scimitar F1 said:

Surprised that the magnetic not the true heading is used as magnetic headings vary all the time.

Yes, you might have to rename a runway as often as every 10 years or so

[Work In Progress]

15 hours ago, Scimitar F1 said:

Mag to Grid - get rid! (as I was taught at Sandhurst)

Not any more. Magnetic variation is currently zero at Greenwich

[Scimitar F1]

1 hour ago, Work In Progress said:

Not any more. Magnetic variation is currently zero at Greenwich

That makes things too easy 😉

[Scooby]

On 9/4/2020 at 10:29 AM, Scimitar F1 said:

Surprised that the magnetic not the true heading is used as magnetic headings vary all the time.

No, compasses are swung to read magnetic heading as close as possible. The runway heading should be the magnetic heading. If all systems fail aircraft are navigating off their magnetic compass.

 

And yes, magnetic headings do vary.

[Scimitar F1]

6 hours ago, Scooby said:

No, compasses are swung to read magnetic heading as close as possible. The runway heading should be the magnetic heading. If all systems fail aircraft are navigating off their magnetic compass.

That is to get rid of magnetic deviation. You do it with boats as well. 
 

That runway headings are changed over time where necessary answers my question.

[noelh]

Ah the joys of learning navigation. Draw a line on the chart, add or subtract magnetic variation. 'East is least west is best.' Easy to get that wrong. Factor in the wind. Get to the aeroplane, view the compass deviation card. Correct your magnetic heading. Set the direction indicator. 

Take off, turn to the heading you worked out, go off course because the wind is  never as forecast. Try to  remember the 1 in 60 rule, go further off course trying to do  the calculations. 

 

Give up,  toss the plog into the back seat and go IFR (I Follow Roads). 

 

Get to the destination. Obtain the active runway over the radio and promptly land downwind on the opposite runway because the compass is spinning like a whirling dervish in the turbulence and you never reset the DI and it has now precessed badly. 

After a couple of bounces you land safely taxy in only to be surrounded by a group of unsmiling gentlemen carrying assault rifles. Because you landed at the military base miles south of your actual destination.🥵

 

Navigation is fun.

 

 

[Sky dancer]

44 minutes ago, noelh said:

Ah the joys of learning navigation. Draw a line on the chart, add or subtract magnetic variation. 'East is least west is best.' Easy to get that wrong. Factor in the wind. Get to the aeroplane, view the compass deviation card. Correct your magnetic heading. Set the direction indicator. 

Take off, turn to the heading you worked out, go off course because the wind is  never as forecast. Try to  remember the 1 in 60 rule, go further off course trying to do  the calculations. 

 

Give up,  toss the plog into the back seat and go IFR (I Follow Roads). 

 

Get to the destination. Obtain the active runway over the radio and promptly land downwind on the opposite runway because the compass is spinning like a whirling dervish in the turbulence and you never reset the DI and it has now precessed badly. 

After a couple of bounces you land safely taxy in only to be surrounded by a group of unsmiling gentlemen carrying assault rifles. Because you landed at the military base miles south of your actual destination.🥵

 

Navigation is fun.

 

 

Noelh,

 

Are you a Ryanair pilot???

[Antti_K]

Hello guys,

 

there are few airfields in the World with confusing magnetic disturbances. One is Port Swettisham, where variation on the runway is something like 30 degrees but if you cross the airport at 2000 feet, the variation is only five degrees.  Use True readings on your gyro...

 

Cheers,

Antti

[noelh]

54 minutes ago, Sky dancer said:

Noelh,

 

Are you a Ryanair pilot???

No they wouldn't  have me. I wonder why?🤔

[TheyJammedKenny!]

9 hours ago, Sky dancer said:

After a couple of bounces you land safely taxy in only to be surrounded by a group of unsmiling gentlemen carrying assault rifles. Because you landed at the military base miles south of your actual destination

This is a true story, and is one excellent reason why one of my colleagues (we'll call him "Chuck") decided wisely not to proceed further with his civilian pilot certificate.   Using the Jersey shore as his reference during a cross-country solo, I believe he ended up on the active military runway at an airport with two parallel runways (one military), a military ramp, and a civilian ramp.  His IP got onto the military side and "took possession" of him and the wayward C-152.  There are old pilots and bold pilots, but no old, bold pilots.  If you can't be safe, don't fly.

[noelh]

12 hours ago, TheyJammedKenny! said:

This is a true story, and is one excellent reason why one of my colleagues (we'll call him "Chuck") ...... There are old pilots and bold pilots, but no old, bold pilots.  If you can't be safe, don't fly.

I confess I didn't  actually make that mistake. But it's  very common. It was after all how the RAF acquired an intact FW190. I did once head for a military runway as a student. My Instructor casually asked if I thinking of enlisting?

 

It works both ways, a test pilot demonstrating an aeroplane to the military performed an impressive high speed low level run in and break as he arrived. Much to the surprise of everyone at the civilian airfield several miles north of the airbase. 

 

As for old and bold. I know at least one one and bold pilot who lived to be 100. Also you have to say Ray Hanna was both old and bold. They are of course the exceptions.

 

Edited September 7, 2020 by noelh

[Dave Swindell]

14 hours ago, TheyJammedKenny! said:

Using the Jersey shore as his reference during a cross-country solo, I believe he ended up on the active military runway at an airport with two parallel runways (one military), a military ramp, and a civilian ramp.

There's only one runway on Jersey, and it's civil and a cross country flight isn't going to take long!