Group captain (Gp Capt or Grp Cpt in the RAF, IAF and PAF, GPCAPT in the RNZAF and RAAF, formerly G/C in the RCAF) is a senior commissioned rank which originated in the Royal Air Force. The rank is also used by the air forces of many countries which have historical British influence and it is sometimes used as the English translation of an equivalent rank in countries which have a non-English air force-specific rank structure. It ranks above wing commander and immediately below air commodore. The name of the rank is the complete phrase, and is never shortened to "captain".
It has a NATO ranking code of OF-5, and is equivalent to a captain in the Royal Navy or a colonel in the British Army or the Royal Marines. Group captain is the rank usually held by the station commander of a large RAF station.
The equivalent rank in the Women's Auxiliary Air Force (WAAF), Women's Auxiliary Australian Air Force (WAAAF), Women's Royal Air Force (WRAF) (until 1968) and Princess Mary's Royal Air Force Nursing Service (PMRAFNS) (until 1980) was group officer. The equivalent rank in the Royal Observer Corps (until 1995) was observer captain which had a similar rank insignia.
On 1 April 1918, the newly created RAF adopted its officer rank titles from the British Army, with Royal Naval Air Service captains and Royal Flying Corps colonels becoming colonels in the RAF. In response to the proposal that the RAF should use its own rank titles, it was suggested that the RAF might use the Royal Navy's officer ranks, with the word "air" inserted before the naval rank title. For example, the rank that later became group captain would have been "air captain". Although the Admiralty objected to this simple modification of their rank titles, it was agreed that the RAF might base many of its officer rank titles on naval officer ranks with differing pre-modifying terms. It was also suggested that RAF colonels might be entitled "Bannerets" or "Leaders". However, the rank title based on the Navy rank was preferred and as RAF colonels typically commanded groups the rank title group captain was chosen. The rank of group captain has been used continuously since 1 August 1919.
Although in the early years of the RAF groups were normally commanded by group captains, by the mid-1920s they were usually commanded by an air officer. In the post-World War II period the commander of an RAF flying station or a major ground training station has typically been a group captain. More recently, expeditionary air wings have also been commanded by group captains.
Insignia and command pennant 
The rank insignia is based on the four gold bands of captains in the Royal Navy, comprising four narrow light blue bands over slightly wider black bands. This is worn on both the lower sleeves of the tunic or on the shoulders of the flying suit or the casual uniform. Group captains are the first rank in the RAF hierarchy to wear gold braid on the peak of their cap, informally known as 'scrambled egg'; however, they still wear the standard RAF officer's cap badge.
The command pennant for a group captain is similar to the one for a wing commander except that there is one broad red band in the centre. Only the wing commander and group captain command pennants are triangular in shape.
Other air forces 
The rank of group captain is also used in a number of the air forces in the Commonwealth, including the Bangladesh Air Force, Ghana Air Force, Indian Air Force (IAF), Nigerian Air Force, Pakistan Air Force (PAF), Royal Australian Air Force (RAAF), Royal New Zealand Air Force (RNZAF) and the Sri Lankan Air Force. In the Republic of Singapore Air Force (RSAF), the rank is simply titled "captain". It is also used in the Egyptian Air Force, Hellenic Air Force, Royal Air Force of Oman and the Royal Thai Air Force.
The Royal Canadian Air Force used the rank until the unification of the Canadian Forces in 1968, when army-type rank titles were adopted. A Canadian group captain then became a colonel. In official French Canadian usage, a group captain's rank title was colonel d'aviation. In the Argentine Air Force commodoro (commodore) is the rank in Argentine Spanish while in the Chilean Air Force, the rank in Chilean Spanish is colonel de aviacion or "colonel of aviation".
An RAAF group captain's sleeve/shoulder insignia
A HAF sminarchos (group captain's) rank insignia
A PAF group-captain's rank insignia.
An IAF group captain's rank insignia
A RTAF group captain's rank insignia
Notable group captains 
- Leonard Cheshire VC, World War II bomber pilot and charity worker.
- Douglas Bader, World War II fighter pilot and double amputee.
- Peter Townsend, World War II pilot and suitor of Princess Margaret.
- Hugh Dundas, World War II fighter pilot. Youngest person to hold this rank (age 24).
- James Stagg, RAF meteorologist involved in the planning of the D-Day invasion.
- Thomas "Loel" Guinness, World War II fighter pilot, politician and businessman
- Lionel Mandrake, fictional officer in the film Dr. Strangelove played by Peter Sellers
- Sachin Tendulkar, honorary group captain for his achievements in cricket.
- Captain Jack Harkness, fictional character in Doctor Who and its spin-off Torchwood carries the rank of group captain on his great-coat, however he is always mistakenly referred to as just "captain".
- Group Captain Ramsey, fictional character in the 1963 film The Great Escape. Official title is Senior British Officer, or SBO.
- Geoffrey Flindell Wood OBE, DFC, worked for the Special Operations Executive (SOE) during World War 2.
- Clive Robertson "Killer" Caldwell DSO, DFC & Bar, Cross of Valor (Poland), Australia's highest-scoring fighter ace and the highest-scoring P-40 pilot from any air force and the highest-scoring Allied pilot in North Africa. Became one of a small group of pilots throughout history to became an "Ace in a day".
See also 
|Commissioned officer ranks of the British Armed Forces|
|NATO rank code||Student Officer||OF-1||OF-2||OF-3||OF-4||OF-5||OF-6
|Royal Navy||O Cdt||Mid||SLt||Lt||Lt Cdr||Cdr||Capt||Cdre||RAdm
|Adm of the Fleet|
|Royal Marines||2Lt||Lt||Capt||Maj||Lt Col||Col||Brig||Maj-Gen||Lt-Gen||Gen
|Army||O Cdt||2Lt||Lt||Capt||Maj||Lt Col||Col||Brig||Maj-Gen||Lt-Gen||Gen
|Royal Air Force||OC / SO||APO / Plt Off||Fg Off||Flt Lt||Sqn Ldr||Wg Cdr||Gp Capt||Air Cdre||AVM||Air Mshl||Air Chf Mshl