OS HQ Maybush | Air Survey Branch

  • This page:Air Survey Branch Overview .
  • Status : Completed [sub pages to be added in a future release.
  • First published: 10 March 2019

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Zeiss Analogue Plotting Instrument 31 March 1982

Photo credit:KM

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This article covers the period of late 1979 to mid 1982.

Air Survey Branch was responsible for the preparation of new large scale mapping, contouring and some revision surveys. Completion was then completed on the ground.

OS and National Context:

A summary of the operating environment for this period:

Ordnance Survey Developments

  • Delays in response by Govt to Serpell Report.
  • Industrial Action due to pay restraint.
  • Peter Wesley undertakes "Study of Revision".
  • European Doppler Network adjustment published as OS SN80.
  • OS joins several external bodies incl European OEEPE
  • Over 500km of Geodetic Network observed.
  • TODDS setup [Fastrak & Ferranti] data capture system based on Vax 11/780 mini-computer
  • Total station on test.
  • Surplus drawing office staff retrain as surveyors
  • West Midlands priority for large scale map digitisation

National & External Developments

  • British Steel workers on strike
  • British Aerospace privatised
  • Public sector pay on hold
  • Utilities form National Joint Utilities Group [NJUG]
  • Michael Foot becomes Labour leader
  • Social Democratic Party party formed
  • Sinclair ZX81 luanched
  • Unemployment reaches 2.5m
  • IRA hunger strikes - 9 deaths
  • Riots: Toxteth & Woolwich
  • Inflation ~ 12%
  • Falklands War


Air Survey Branch | Role, Operations, People & Equipment:



Ordnance Survey, Romsey Road. Maybush,
Southampton, SO9 4DH

This office was Ordnance Survey Headquarters

Air Survey Branch was housed on the ground floor[1} of North Block [now named Compass House]

Building still exists: Yes

The floor was "suspended" in that it was meant to be free from external vibrations - since the mechanical instruments were very sensitive.


Air Survey Branch was managed by Major M. Neale, supported by a middle manager [Ted ?], 2-3 Chief Surveyors and ~30 staff.


Air Survey Branch was supported by the following types of equipment during this period:

Analogue Plotting Equipment

  • Wild A10 [x2] [a]
  • Wild A4 [~x12] [b]
  • Kern PG2 [x2]
  • Thompson Watts [x2]

[a]original 1970's purchase cost ~£80k each
[b] original 1970's purchase cost ~£54k each

Photography acquisition & Aerial Triangulation

  • Aerial Cameras - type unknown [2-3]
  • Stereo Comparator - make unknown

The flying unit was normally based at Blackpool using a contracted aircraft - though other aircraft may be hired in busy seasons and stationed elsewhere.

Main activities of Air Survey Branch at this time:

1:10,000 Contouring

The main programme at this time was to complete national cover of metric contours. Strangely, given the Davidson Report's commitment to metric in 1938 OS covered around 25% of Gt Britain with imperial contours before it was decided to go metric. Hence this programme was systematically resurveying some areas and filling in gaps elsewhere.

1:1,250 Resurvey

Growing small towns mapped at 1:2500 were considered for upgrading to 1:1250 after they reached certain criteria eg population >20,000. Air survey was now the standard procedure - all features visible on the stereo photographs would be plotted and the field surveyor would then complete the map. Formby was one such town (se article below).

1:2500 Resurvey

The poor positional accuracy of some 1:2500 areas (noted in the 1970s pages) occasionally led to the resurvey of those areas (usually small towns). The process was similar to 1:1250 resurvey above.

Continuous Revision - all three scales

Where local change was significant enough to make aerial photography economic then such areas were processed in air survey and completed on the ground.

Aerial Photography & Triangulation

All the foregoing activities required aerial photography and this had to be planned, programmed and executed. Easier said than done, planning was done in the winter, photo acquisition was subject the the British summer cloud cover.

Aerial triangulation was prepared for all contouring and resurvey work and for revision where survey control required strengthening. Aerial triangulation is a technique that densification of a network of control points/stations so that each overlapping pair of photos usually contains six control points [E, N & Ht].

Aerial Photography Rectification

Where aerial photographic enlargements are used ie the Air Ground method, the enlagements have to be prepared at the appropriate scale ans the nadir point determined. Post the 1:200 Overhaul Programme this work was much reduced.

Overseas mapping

Residual staff from the disbanded Directorate of Overseas Surveys started to join OS from 1983 onwards and some of these joined Air Survey. They brought the remains of a reducing overseas survey programme with them.

Out of the Ordinary

  1. Following the Hermitage training course we started work in air survey just before Christmas 1979 and witnessed something we and never seen before - elaborate Christmas decorations. It appeared to be a tradition at headquarters by the drawing office staff. The air survey section included a cardboard aircraft that travelled on a cable between two pillars. These were the dying days though and within 4-5 years they had just about gone altogether.

Personal highlights:

This period started in October 1979 with the Air Survey Operators Course at Hermitage, we were then posted to Southampton. The posting was conveniently made it easier to undertake the Surveying & Cartography course [OND-BTEC] at Southampton Technical College.

There was a lot of work variety in Air Survey (which was still 100% map hardcopy based at that time.

Last Updated: 15 Apr 2019
KM v2.01