Distances from airfields stated in official WWII documents.

When researching crash sites the station ORB's and ARC's occassionally state distances from the airfield in miles. Either I'm being a bit dim or there is no SOP for measuring distances from an airfield judging by the number inaccuracies I'm finding.

When measuring the distance from an airfield to a crash site, where exactly is the distance to the crash site taken from? ...the threshold of the runway in use? ...the end of the runway in use? ...the centre of the airfield? ...the Watch Tower?

Cheers,

Garth.

I dont know what the procedure was in wwii, but nowadays everything is measured from what is called the aerodrome reference point. This is the highest point on an aerodrome.

canberra wrote:

I dont know what the procedure was in wwii, but nowadays everything is measured from what is called the aerodrome reference point. This is the highest point on an aerodrome.

Actually no, changed over 20 years ago after the present defintion of the Aerodrome Traffic Zone (ATZ) was introduced. (2nm radius for airfields with a main runway of 1850m or less and 2.5nm radius if the main runway is more than 1850m; was previously 1.5nm from the airfield boundary although when this definition was introduced I don't know)
The aerodrome reference point nowadays is the central point of the main runway and the point from which the ATZ is measured..
Aerodrome elevation which used to be taken at the aerodrome reference point and thus might be higher or lower than the runway threshold(s) is now 'the highest point on the landing area' as opposed to on the entire aerodrome.

Is that the same for military and civil airfields???

Yes all airfields come under the same criteria now.; the CAA and their military equivalent the MAA are steadily working towards 'standardising' everything with for instance military and civil ATC phraseology being both the same now (both as per CAP413) apart from extra messages which would only be used at a military airfield eg 'cable/barrier up' and things like that.
I only found out in about 2001 about elevation and ARP when I needed to work out the ARP and elevation for the civil licence for Farnborough Airport and I took advice from No 1 AIDU at Northolt.; until then we'd still had the ARP notified as the centre of the central grass area (as with most military airfields in the past assuming 3 runways) and elevation the highest point on the airfield.
To find the ARP, I took my GPS and drove up and down the runway several times coming to a stop at the same point every time and checking the lat and long. I submitted the averaged result to Northolt and they said it was the same as what they had worked out from surveys..
Airfield Elevation was a bit easier; when the runway had been re-surfaced it was levelled in several places (taking out a 'hump' which according to an OC Flying, tended to force a Hunter into the air just before it reached flying speed) so TAG commisioned a survey which took spot heights about every 100m along the runway (the 2 subsidiary runways had been de-commisioned by this time) so I just went through the survey until I found the highest point which was at the western end where it narrowed from full width to reduced width for the runway 06 starter extension which as it was for aircraft taking off only, wasn't included as part of the 'landing area' even though the ground continues to rise along it.
Both runway thresholds are lower than AD elevation but this is not unusual; in the last few years of MOD flying we'd had to issue 'QFE threshold'* as well as airfield QFE to the MOD movements and QNH to civil ones but when MOD flying moved out we switched to QNH as the main pressure datum with threshold elevations shown on the TAPs so this made things easier.

*Ourselves (ATC) and the Farnborough met office forecasters had been aware for years that we should have been issuing 'QFE threshold' but in order to 'keep it simple', nobody had mentioned it to the RAF then when the RAF changed back from using QNH to QFE, somebody noticed so met had to work out new QFE computations for each threshold which we had to pass on to military pilots.