November 19th 1933
- First UK Air Traffic Control Service established at London Croydon
Due to the ever increasing
danger of aerial collisions in bad weather, the first UK Air Traffic Control
service was introduced at Croydon Airport, London. An irregularly shaped
Control Zone based on geographical features came into operation when visibility
dropped to below 1000 yards or cloud was below 1000ft - in the 'Q' code
used for the W/T (morse) communications of the day this was 'QBI'. Standard
routes were also defined over south east England, mainly following railway
lines and using the 'right hand traffic' rules to avoid collisions.
     
Ronaldsway Airport
Ronaldsway had first
been granted a licence in 1934 for operations by Blackpool & West Coast
Air Services, using De-Havilland Dragon aircraft. The landing distance
available was very small, at only 560 yards. Fuel was supplied by Shell
and at first the Derbyhaven Hotel used by passengers as no facilities were
provided at the airfield. In 1935 the landing area was expanded and the
airfield now operated by Isle of Man Air Services. By 1936 aircraft
hangerage was provided and a wooden terminal building constructed.
Airfield details and
diagram, landing distances and the hanger date this at around 1936/37 which
put it at around the time of establishment of the first Air Traffic Control
unit at Ronaldsway
   
Some pictures of the
airport in the 1930s courtesy of the Terry Farragher Collection
    
July 1937, Air Traffic
Control Service Established at Ronaldsway - 'GJE' on 363Khz
Only three and a half
years after ATC started at Croydon Airport, Air Traffic Control was established
at Ronaldsway Airport. This was due to the large number of commercial flights
operating to the Isle of Man. Whereas in the UK, the preferred mode of
long distance travel for most was by the extensive railway network, travel
to the island involved a lengthy and often rough boat journey across the
Irish Sea. Air travel for those who could afford it was much faster and
more comfortable.
Ronaldsway first
'Control Tower'
The first ATC 'Watch
Office' at Ronaldsway. Located at Derbyhaven, the wireless station and
Bellini-Tosi Direction Finding equipment would have been nearby, signals
to aircraft and other ground stations being passed to the W/T operators
on slips of paper for transmitting to aircraft by Morse Code. Replies would
be similarly passed on message slips. Final permission to land or take-off
would be given by Aldis signalling lamp or a coloured very pistol signal.
 
The Controlled Zone
A 'Controlled Zone'
was established on the 8th July 1937 comprising a circle 10 miles around
Ronaldsway to a height of 3000 ft. Control only came into action in 'QBI'
- i.e. poor weather conditions. The principle was one aircraft inside
the zone at a time, arriving and departing aircraft could be assigned levels
to fly and expected times to enter the zone.
If QBI was not in force,
aircraft could arrive overhead the airfield to observe the ground signals
square, which would give them the information needed as to landing and
circuit direction. As the airfield was grass, with no delineated runways,
the 'Landing Tee' was pivoted to rotate with the wind and pilots would
always land into wind. In light winds the Tee would be fixed in one direction
to avoid confusion if it drifted around.. Pilots would then join
the visual circuit keeping a good lookout for other aircraft and wait for
a visual landing signal on final approach.
    
Irish Sea Communications
Area
A 'Communications Area'
was established over the northern Irish Sea, jointly administered by Ronaldsway
and Manchester Barton, although Barton seems to have been the senior partner.
Positions of aircraft would be plotted on a map based either on position
reports from the pilots or on ground based direction finding bearings.
A frequency of 363 KHz was used (by both Ronaldsway and Barton), using
W/T - wireless telegraphy by means of Morse Code. (Radio telephony had
been used by aircraft previously, but was abandoned in 1929 due to congestion
on the very limited frequencies available). Radio equipped aircraft would
carry a wireless operator as it would not have been practical for the pilot
to both fly the aeroplane and operate the radio. Direction finding bearings
would be available to assist pilots in navigation, but this would be a
time consuming process as bearing were manually obtained at the ground
stations before being re-transmitted to the aircraft. To keep messages
short, the 'Q' code was used, most regular phrases needed being covered
by a three letter code starting with the letter Q. Some of these are still
used everyday in modern ATC, such as QNH - the pressure to set on an altimeter
to indicate vertical distance above mean sea level and QDM - the heading
to steer to reach the airfield in zero wind conditions.
'Flight' pages from
1936 - 1938
Contemporary pages from
the 'Flight' archives regarding Air Routes, setting up Ronaldsway ATC and
a map of
'The Control System
as it is Today' January 20th 1938. There were only four Communications
Areas and six Controlled Zones. Seventeen ground radio stations for aeronautical
communications are shown.
  
Adcock Direction
Finding Station at Red Gap, Castletown
A second direction finding
station was established in the late 1930s to the west of Ronaldsway, using
the 'Adcock' system which gave more accurate bearings during the hours
of darkness. This needed to be located away from the airfield due to the
four 100ft high radio masts needed. These were arranged in a square with
a quite large building in the centre, housing the wireless equipment and
plotting table, which is still in existance in 2010.
   
A typical flight
to Ronaldsway in QBI conditions
Follow the flight of
Dragon Rapide G-AFFF from Glasgow Renfrew to Ronaldsway on the 14th June
1939. The weather was poor at Ronaldsway so the Controlled Zone was in
operation (QBI). Each slip represents a message sent using Morse Code between
the aircraft and a ground station. Extensive use was made of the 'Q Code'
to shorten transmissions. There were 33 messages in total to get
one aircraft into land! The 'ATC Diary' entry for the day indicates that
QBI had been in force from 07:55. If I've worked this out correctly. pink
slips are for arrival and departure messages, white slips for 'general'
messages from and to the W/T station and green slips are for Air
Traffic Control messages.
  
Even in
this period ATC was becoming
overloaded with traffic and it was suggested that medium frequency radio
'beacons' were set up to allow suitably equipped aircraft to obtain their
own bearings to stations using on board direction finding equipment. The
equipment was bulky which meant that it was only really practical in the
airliners of the day. Today, we still have 'NDBs' - medium frequency Non
Directional Beacons that aircraft can home to. In the Isle of Man we have
the 'RWY' on 359 KHz situated on the airport, with the 'CAR' on 366.5 situated
at Carnane, just south of Douglas, both frequencies very close to the 363
Khz originally used at Ronaldsway.
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