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Royal Air Force Conversion Units
Ensign of the Royal Air Force
Ensign of the Royal Air Force

Conversion Units and Operational Conversion Units (OCU) were training units of the Royal Air Force.

History[]

With the introduction of the new heavy bombers, the 4-engined Short Stirling, Avro Lancaster and Handley Page Halifax, into service, the Royal Air Force introduced Heavy Conversion Units. The Heavy Conversion Units began forming in late 1941 to qualify crews trained on medium bombers to operate the heavy bombers prior to assignment to an Operational Training Unit to gain experience before final posting to the operational squadrons.

After the end of the war their role was taken over by the Operational Conversion Units. Although the units had nominal bases it was usual for different flights and individual aircraft to be detached nearer the operational bases. Some of the Heavy Conversion Units were involved in bombing operations over Germany.

Royal Air Force Operational Conversion Units (OCU) are training units that prepare aircrew for operations on a particular type or types of aircraft or roles. Some OCUs have a Shadow or reserve squadron designation which is used if the unit has a war role.

List of Conversion Units[]

Unit Dates Aircraft Base Notes
226 OCU
Aug 46–Aug 49
Sep 49–Jun 55
Jun 63–Sep 74
Oct 74–Sep 91




Oxford I, Beaufighter X
Hornet F.1
Mosquito III / TT.35
Tiger Moth II
Vampire F.1 / FB.5 / T.11
Meteor F.3 / F.4 / T.7 / F.8 / FR.9
Tempest II
Martinet I
Spitfire XIV / XVI / XVIII / XIX / F.22
Javelin T.3
Lightning F.1 / F.1A / F.3 / T.4 / T.5
Jaguar GR.1 / T.2







RAF Molesworth
RAF Bentwaters
RAF Driffield
RAF Stradishall
RAF Middleton St. George
RAF Coltishall
RAF Lossiemouth
Formed at Molesworth by re-designating 1335 (Meteor) CU. Disbanded at Driffield to become 203 AFS. Re-formed at Stradishall by renaming 203 AFS.Re-formed at Middleton St. George by merging the Lightning Conversion Squadron and the Fighter Command Instrument Rating Squadron. Disbanded at Coltishall. Immediately re-formed at Lossiemouth by re-designating the Jaguar Operational Conversion Unit.
Disbanded at Lossiemouth to become 16 (Reserve) Sqn
227 OCU
227 (AOP) CU
May 47–Dec 47
December 47–May 50
Tiger Moth II
Oxford I
Auster V
Auster VI
Auster T.7
Auster A.2/45
Harvard IIB
RAF Andover
RAF Middle Wallop
Formed by re-designation of 43 OTU
Became the Air Observation Post School.
228 OCU May 47–Sep 61
May 65–Dec 66
August 68–Jul 92




Martinet I
Master II
Oxford I
Tiger Moth II
Brigand B.1 / T.4 / T.5
Tempest V
Buckmaster T.1
Wellington XVIII
Mosquito III / VI / NF.30 / TT.35 / NF.36
Balliol T.2
Valetta C.1 / T.3 / T.4
Prentice T.1
Vampire T.11
Meteor F.4 / T.7 / NF.11 / NF.12 / NF.14
Anson XIX
Chipmunk T.10
Javelin T.3 / FAW.5 / FAW.7 / FAW.9
Canberra T.4 / T.11
Phantom FGR.2
Jet Provost T.4




RAF Leeming
RAF Leuchars
RAF Coningsby



Formed by merging 13 OTU and 54 OTU
Became 64 (R) Sqn
229 OCU Dec 50–Sep 74
November 84–Jul 92




Vampire FB.5 / T.11
Meteor T.7 / F.8 / TT.8
Hunter F.1 / F.4 / F.6 / T.7 / FGA.9 / FR.10
Tempest V
Beaufighter X
Oxford I / II
Mosquito III / TT.35
Martinet I
Anson T.21 / T.22
Sabre F.2 / F.4
Chipmunk T.10
Jet Provost T.3A
Tornado F.2(T) / F.3
RAF Leuchars
RAF Chivenor
RAF Brawdy
RAF Coningsby



Formed from 'B' and 'D' Flights of 226 OCU.
Reformed 1957 at Chivenor, still there late 1962 Relocated to RAF Brawdy mid 1960s
Disbanded 2 September 1974 at Brawdy to become the Tactical Weapons Unit
Designated 65 (Shadow) Squadron from 31 December 86
Became 56 (R) Sqn.
230 OCU Mar 47–Oct 52
August 53–Feb 55
May 56–Aug 81




Lancaster I / III
Lincoln B.2
Mosquito III / B.35 / NF.36
Tiger Moth
Anson XIX
Vulcan B.1 / B.2
Hastings T.5
Canberra T.4
RAF Lindholme
RAF Scampton
RAF Upwood
RAF Waddington
RAF Finningley
RAF Scampton
Formed by re-designting 1653 HCU
Disbanded 15 oct 52 to become the Reserve Training Squadron
became the Lincoln Conversion Flight at Upwood 1 February 1955.
231 OCU Mar 47–Dec 49
December 51–Dec 90
May 1991–Apr 93




Lancaster I / III
Anson XII / XIX / T.22
Mosquito III / VI / XVI / PR.34 / PR.34A / B.35
Chipmunk T.10
Meteor T.7 / PR.10
Canberra B.2 / PR.3 / T.4







RAF Coningsby
RAF Waddington
RAF Bassingbourn
RAF Cottesmore
RAF Marham
RAF Wyton
Formed by re-designating 16 OTU
re-formed at Bassingbourn by re-designation of 237 OCU
Dis-banded at Wyton, 15 December 1990, to become the Canberra Standardisation and Training Flight
Re-formed at Wyton 13 May 1990 from the Canberra Standardisation and Training Flight
232 OCU Feb 55–Jun 65
February 70–Apr 86
Valiant B.1
Victor B.1 / B(PR).1 / B.1A / B.2 / BK.2
Canberra T.4
RAF Gaydon
RAF Marham
At Gaydon, 30 June 1965, the Victor element became the Tanker Training Flight
Re-formed at Marham 6 February 1970 by amalgamating the Victor (B.2) Training Flight and the Victor Training Unit
233 OCU Sep 52–Sep 57
October 70–Sep 92




Vampire FB.5 / FB.9 / T.11
Balliol T.2
Meteor T.7 / F.8
Oxford I
Tiger Moth II
Mosquito III / PR.34A / TT.35
Tempest V
Chipmunk T.10
Hunter F.1
Harrier GR.1 / GR.1A / GR.3 / GR.3A / T.2 / T.4 / T.4A / GR.5







RAF Pembrey[1]
RAF Wittering



Became 20 (R) Sqn
235 OCU Jul 47–Oct 53



Sunderland V
Short Seaford







RAF Calshot



Became the Flying Boat Training Squadron
236 OCU Jul 47–Sep 56
July 70–Sep 92




Lancaster III
Oxford I / II
Beaufighter X
Shackleton GR.1 / MR.1A
Neptune MR.1
Martinet I
Tiger Moth II
Spitfire XVI
Vampire FB.5
Anson XI / XIX
Mosquito TT.35
Brigand T.5
Buckmaster T.1











RAF Kinloss
RAF St Mawgan



Formed by re-designating 6 OTU
237 OCU Jul 47–Dec 51
October 56–Jan 58
March 71–Oct 91




Oxford I
Mosquito III / PR.34 / PR.34A
Spitfire XVI / XIX
Harvard IIB
Meteor T.7 / PR.10
Canberra PR.3 / T.4
Hunter F.6 / T.7 / T.7A / T.7B / T.8C
Buccaneer S.2A / S.2B







RAF Benson
RAF Bassingbourn
RAF Wyton
RAF Honington
RAF Lossiemouth



Formed by re-designating 8 OTU
Became 231 OCU at Bassingbourn.
Re-formed at Wyton, 56, by re-designating 'C' Squadron of 231 OCU.
Re-absorbed by 231 OCU 2001 January 58.
238 OCU 1Jun 52–Mar 58



Buckmaster T.1
Brigand T.4 / T.5
Mosquito TT.35
Balliol T.2
Meteor NF.12 / NF.14
Valetta C.1 / T.3











RAF Colerne
RAF North Luffenham



Formed by re-designating the Airborne Interception School
240 OCU Jan 48–Apr 51
December 71–Oct 93




Anson I / X / XII / XIX
Dakota IV
Hastings MET.1
Valetta C.1
Wessex HC.2
Puma HC.1
ChinookHC.1







RAF North Luffenham
RAF Odiham



Formed by merging 1333 (TS)CU with 1382 (T)CU
241 OCU Jan 48–Apr 51
July 70–Oct 93




York C.1
Halifax IX
Hastings C.1
Valetta C.1
Tiger Moth II
Anson XI / XII
Brittania C.1 / C.2
Andover C.1
Belfast C.1
VC10 C.1
Tristar C.1
BAe 146











RAF Dishforth
RAF Brize Norton



Formed by re-designating 1332 HTCU.
Became No. 55 (Reserve) Squadron RAF
242 OCU Apr 51–Jul 92



Valetta C.1
Hastings C.1 / MET.1 / C.1A
Beverley C.1
Argosy C.1
Andover C.1
Hercules C.1 / C.1K / C.1P / C.3
Tiger Moth II
Anson XII
Chipmunk T.10







RAF Dishforth
RAF Lyneham



Became 57 (R) Sqn
1330 CU Jun 44–Mar 46 Harvard IIA
Baltimore IV / V
Vengeance IV
Hudson IIIA
Expeditor I
Marauder II / III
Ventura V
Hellcat II
Beaufighter X
Spitfire Vb
Mustang IVA
Anson I
Dakota I / III
Douglas DC-2
Mosquito III / IV
Oxford I



RAF Bilbeis 1 (Middle East) Check and Conversion Unit re-designated.
1331 CU
1331 HTCU
Sep 44–Jan 46
December 46–Jan 48
Harvard IIB
Vengeance IA / II / IV
Beaufighter VI / X
Spitfire VIII
Mustang IV
Mosquito III
Oxford I
Blenheim V
Thunderbolt I / II
Hurricane IIC
Wellington XVI
Liberator III / VI
RAF Mauripur
RAF Risalpur
RAF Syerston



Formed by re-designating Check and Conversion Flight.
1332 (T)HCU
1332 HTCU
Sep 44–May 47
May 47–Jan 48




Liberator III / V /VI / VII / IX
York C.1
Stirling III
Halifax VII / IX
Skymaster C.1
Oxford I











RAF Longtown
RAF Dishforth



Became 241 OCU.
1333 (TS)CU
1333 TSCU
Mar 45–Jul 46
July 46–Jan 48




Dakota III / IV
Horsa I / II
Halifax VII / IX
Oxford II
Miles Magister
Tiger Moth
Proctor IV
Auster III







RAF Leicester East
RAF North Luffenham



Formed by re-designating 107 OTU
Merged with 1382 (T)CU to become 240 OCU.
1334 (TS)CU Apr 45–Mar 45



Dakota III / IV







RAF Gujrat
RAF Baroda



1335 (M)CU Mar 45–Aug 46



Meteor F.1 / F.3
Oxford II
Martinet I







RAF Colerne
RAF Molesworth



Became 226 OCU
1336 (TS)CU
1336 TCU
Jun 45–Mar 46



Dakota III







RAF Welford



1380 (TS)CU
1380 TCU
Aug 45–Jan 46



Wellington X
Anson I
Proctor II







RAF Tilstock



Formed by re-designating 81 OTU
1381 (T)CU Aug 45–Feb 48



Dakota III / IV
Wellington X
Miles Magister
Tiger Moth II
Oxford I







RAF Bramcote
RAF Dishforth



Formed by re-designating 105 OTU
1382 (T)CU Aug 45–Jan 48



Oxford I
Miles Magister
Dakota III / IV







RAF Wymeswold
RAF North Luffenham



Formed by re-designating 108 OTU
Merged with 1330 TSCU to form 240 OCU.
1383 (T)CU Aug 45–Aug 46



Dakota III
Oxford II
Halifax VII







RAF Crosby-on-Eden



Formed by re-designating 109 OTU
1384 (HT)CU Nov 45–Jun 46



Dakota I
Oxford I
York C.1







RAF Ossington
RAF Wethersfield



Formed by re-designating No. 6 Lancaster Finishing School RAF
1385 (HTS)CU Apr 46–Jun 46



Stirling V
Halifax VII
Horsa II
Oxford I







RAF Wethersfield



Absorbed by 1333 TSCU
1584 (HB)CU Nov 43–Feb 44



Liberator III







RAF Kolar
RAF Salbani



Formed by re-designating No 1584 (Heavy Bomber Conversion) Flight RAF.
Became 1673 HCU.
1651 CU
1651 HCU
Jan 42–May 44
May 44–Mar 45
March 45–Jul 45




Stirling I / III
Lancaster I / III
Oxford I
Spitfire Vb
Tiger Moth II
Beaufighter X
Halifax II







RAF Waterbeach
RAF Wratting Common
RAF Woolfox Lodge



During 42 it flew 49 operational sorties for RAF Bomber Command with a loss of five aircraft.
Formed by merging No. 26 Conversion Flight RAF and No. 106 Conversion Flight RAF.
Absorbed 15 Squadron Conversion Flight and 24 Squadron Conversion Flight.
1652 CU
1652 HCU
Jan 42–Jun 45



Halifax I / II / III / V
Spitfire Vb
Hurricane IIC
Spitfire Vb
Hurricane IIC / IV







RAF Marston Moor
RAF Bentwaters



During 42 it flew 42 operational sorties for RAF Bomber Command with a loss of three aircraft.
Formed by merging No. 28 Conversion Flight RAF and No. 109 Conversion Flight RAF.
Absorbed 35 Squadron Conversion Flight
1653 CU
1653 HCU
Jan 42–Oct 42
November 43–Nov 46




Liberator II
Stirling I / III
Lancaster I / III
Blenheim IV
Ventura I
Mosquito XIX
Hurricane IIC
Spitfire Vb
Beaufighter VI







RAF Polebrook
RAF Burn
RAF Chedburgh
RAF Lindholme
RAF North Luffenham



Formed by re-designating No. 108 Conversion Flight RAF
Became No. 230 Operational Conversion Unit RAF in March 47.
1654 CU
1654 HCU
May 42–Jul 42
July 42–Sep 45




Manchester I
Lancaster I
Halifax II / V
Stirling III
Oxford I
Hurricane IIC
Spitfire Vb







RAF Swinderby
RAF Wigsley



During 42 it flew 12 operational sorties with a loss of two aircraft.
1655 MCU Aug 42–May 43



Mosquito III / IV / XVI / B.20 / B.25
Blenheim IV
Oxford I







RAF Horsham St. Faith
RAF Upper Heyford
RAF Marham
Became Mosquito Training Unit RAF at RAF Marham



1656 HCU Oct 42–Nov 45



Lancaster I / III
Halifax II / V
Manchester I
Spitfire IIa / Vb
Hurricane IIC







RAF Lindholme
Tiger Moth II



Formed by merging 103 and 460 Squadron Conversion Fights.
1657 HCU Oct 42–Dec 44



Stirling I / III / IV
Lancaster I / II
Tomahawk IIB
Oxford II
Hurricane IIC







RAF Stradishall



Formed by merging 7, 101 and 149 Squadron Conversion Fights.
1658 HCU Oct 42–Apr 45



Halifax I / II / III
Oxford II
Hurricane IIC







RAF Riccall



Formed by merging 10, 76 and 78 Squadron Conversion Fights.
1659 HCU Oct 42–Mar 43
March 43–Sep 45




Halifax I / II / III
Lancaster I / III
Oxford II
Spitfire IIa / Vb
Hurricane IIC
Tiger Moth







RAF Leeming
RAF Topcliffe



Formed by merging 405 and 408 Squadron Conversion Fights.
Trained Canadian aircrew.
1660 HCU Oct 42–Nov 46



Lancaster I / II / III
Halifax II
Manchester I
Mosquito XIX
Stirling I / III
Oxford I
Spitfire Vc
Hurricane IIC
Lysander I
de Havilland Puss Moth







RAF Swinderby



Formed by merging 61, 97, 106 and 7 Squadron Conversion Fights.
Absorbed by No 1653 Heavy Conversion Unit RAF
1661 HCU Nov 42–Aug 45



Lancaster I / II
Halifax II / V
Manchester I
Mosquito XIII
Stirling III
Oxford II
Spitfire Vb
Hurricane IIC











RAF Waddington



Formed by merging 9, 44 and 49 Squadron Conversion Fights.
Short Stirlings replaced the planned re-equipment with Handley Page Halifaxs.
1662 HCU Jan 43–Apr 45



Lancaster I / II
Halifax I / II / III / V
Oxford II
Spitfire Vb
Hurricane IIC
Tiger Moth II







RAF Blyton



1663 HCU Mar 43–May 45



Halifax I / II / III / V
Stirling I
Oxford II
Spitfire Vb
Hurricane IIC







RAF Rufforth



1664 HCU
1664 (RCAF)HCU
May 43–Apr 44
April 44–Apr 45




Lancaster I / III
Halifax II / III / V
Oxford II
Spitfire Vb
Hurricane IIC







RAF Croft
RAF Dishforth



The unit had the Canadian name Caribou.
1665 HCU
1665 (HT)CU
Apr 43–Jun 43
June 43–Jan 44
January 44–Aug 45
August 45–Jul 46




Halifax III / V / VI / VII
Stirling I / III / IV
Oxford II
Spitfire IIa / Vb
Hurricane X
Tiger Moth II
Mosquito VI
Lancaster I











RAF Mepal
RAF Woolfox Lodge
RAF Tilstock
RAF Saltby
RAF Marston Moor
RAF Linton-on-Ouse



Re-designated as 1665 (HT)CU on 10 August 1945
1666 HCU
1666 (RCAF)HCU
Jun 43–Oct 43
October 43–Aug 45




Halifax II / III / V
Lancaster I / II / III
Oxford II
Spitfire IIa / Vb
Hurricane IIC







RAF Dalton
RAF Wombleton



The unit had the Canadian name Mohawk.
1667 HCU Jun 43–Oct 43
October 43–Feb 44
February 44–Nov 45




Halifax II / V
Oxford II
Spitfire Vb
Hurricane IIC
Tiger Moth II
Lancaster I / III







RAF Lindholme
RAF Faldingworth
RAF Sandtoft



1668 HCU Aug 43–Nov 43
July 44–Mar 46




Lancaster I / II / III / X
Mosquito XIX
Spitfire Vb
Hurricane IIC
Beaufighter VI











RAF Balderton
RAF Bottesford



Dis-banded November 43, re-formed July 44.
1669 HCU Aug 44–Mar 45



Handley Page Halifax
Lancaster I / III
Spitfire Vb
Hurricane IIC







RAF Langar



1670 (T)CU Jun 44–Jan 45



Thunderbolt
Harvard IIB







RAF Yelahanka



Became 8 Refresher Flying Unit
1670 CU Feb 44–Jun 44



Beaufighter VI







RAF Baigachi



Formed from AI MkVIII Conversion Flight
1670 (M)CU Feb 44–Aug 45



Blenheim V
Mosquito III
Oxford I







RAF Yelahanka



1673 HCU Feb 44–Apr 44
April 44–Nov 44




Liberator III
Tiger Moth II
Anson I







RAF Salbani
RAF Kolar



Formed by re-designating No 1584 (Heavy Bomber) Conversion Unit RAF.
1674 HCU Oct 43–Nov 45



Liberator III / V / VI / VIII
Halifax II
Fortress I / II / IIA
Wellington XIII
Oxford I / II
Hurricane IIC
Martinet I







RAF Aldergrove
various bases in Northern Ireland
RAF Lossiemouth



1675 HCU Oct 43–Aug 44
August 44–Oct 45




Liberator II
Harvard IIA
Hurricane IIB
Argus II







RAF Lydda
RAF Abu Sueir



Formed by re-designating 5 Heavy Bomber Conversion Unit, Lydda
1678 HCU Sep 43–Jun 44



Lancaster II







RAF Foulsham
RAF Waterbeach


1699 (BS)CU
1699 HCU
Oct 44–Jun 45



Fortress II / III
Liberator VI
Lancastrian II







RAF Oulton
RAF Full Sutton



Became the Lancastrian Flight of No. 231 Squadron RAF
All-Weather OCU ?–?

Anson T.21
Vampire T.11
Meteor T.7 / F.8 / NF.12 / NF.14







nomadic



Argosy CU Nov 61–Apr 63



Argosy C.1







RAF Benson



Became the Argosy Flight of OCU
Belvedere CU Aug 64–Aug 68



Belvedere HC.1







RAF Odiham



Absorbed by the Short-Range Conversion Unit
Short-Range CU Aug 64–Jul 67



Twin Pioneer CC.2
Wessex HC.2
Auster AOP.9







RAF Odiham



Became the Helicopter Operational Conversion Flight
Jaguar OCU Jun 74–Sep 74



Jaguar GR.1 / T.2







RAF Lossiemouth



Formed from Jaguar Conversion Team.
Became 226 OCU
5 Heavy Bomber Conversion Unit, Lydda ?–?



Liberator







RAF Lydda



Became 1675 HCU
Heavy Bomber Conversion Unit, Salbani Sep 42–Jul 43



Liberator III







RAF Salbani



Became 1584 HCU
Heavy Glider Conversion Unit Jul 42–Oct 44

Whitley V
Albemarle I / GT.I / ST.II / ST.V
Horsa I / II
Oxford I / II
Tiger Moth II
Miles Magister







RAF Shrewton
RAF Brize Norton



Became No 21 Heavy Glider Conversion Unit
21 HGCU Oct 44–Dec 47



Whitley V
Albemarle GT.VI
Horsa I / II
Oxford I
Tiger Moth I
Miles Magister
Hotspur II / III
Hadrian I
Stirling IV
Halifax III / VII
Master II










RAF Brize Norton
RAF North Luffenham



Formed by re-designation of the Heavy Glider Conversion Unit
22 HGCU Oct 44–Dec 47



Albemarle GT.I / ST.II / ST.V / GT.VI
Horsa I / II
Oxford I
Hadrian I




RAF Keevil
RAF Blakehill Farm
Formed by re-designation of an element of the Heavy Glider Conversion Unit
23 HGCU Oct 44–Dec 45 Albemarle GT.I / ST.V / ST.VI
Horsa I / II
Oxford I
Hadrian I
Proctor III
RAF Peplow Formed by elements of 83 OTU the Heavy Glider Conversion Unit

See also[]

Notes[]

References[]

  • Jefford, Wing Commander C.G., MBE,BA,RAF (Retd). RAF Squadrons, a Comprehensive Record of the Movement and Equipment of all RAF Squadrons and their Antecedents since 12. Shrewsbury: Airlife Publishing, 98 (second edition 01). ISBN 1-84037-141-2.
  • Sturtivant, Ray ISO and John Hamlin. RAF Flying Training And Support Units since 12. Tonbridge, Kent, UK: Air-Britain (Historians) Ltd, 07. ISBN 0-85130-365-X.
  • Ray Sturtivant, Flying Training And Support Units since 12, 07, Air-Britain, UK, ISBN 0-85130-365-X
  • Lake, Alan. "Flying Units of the RAF".Airlife Publishing. Shrewsbury. 1999. ISBN 1-84037-086-6

External links[]



All or a portion of this article consists of text from Wikipedia, and is therefore Creative Commons Licensed under GFDL.
The original article can be found at List of Royal Air Force Conversion Units and the edit history here.
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