Chief technician is a non-commissioned

Non-commissioned officer

A non-commissioned officer , called a sub-officer in some countries, is a military officer who has not been given a commission...

 rank in the Royal Air Force

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 which is only held by airmen in technical trades and by musicians. It is between sergeant

Sergeant

Sergeant is a rank used in some form by most militaries, police forces, and other uniformed organizations around the world. Its origins are the Latin serviens, "one who serves", through the French term Sergent....

 and flight sergeant

Flight Sergeant

Flight sergeant is a senior non-commissioned rank in the British Royal Air Force and several other air forces which have adopted all or part of the RAF rank structure...

 and, like the latter has a NATO code of OR-7. Airmen in non-technical trades progress directly from sergeant to flight sergeant. Along with junior technician

Junior Technician

Junior Technician is a junior non-commissioned rank in the Royal Air Force and the Pakistan Air Force. In the RAF it ranks equal to Senior Aircraftman Technician , above Senior Aircraftman and below Corporal and has a NATO rank code of OR-2...

 this is a survivor of a separate ranking system for technicians introduced in 1950 and abolished in 1964. During that period it was equivalent to flight sergeant, but was made junior to that rank in 1964. Chief technicians are usually addressed as "Chief".

Rank insignia

The rank badge is three chevrons below a four-bladed propeller

Propeller

A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

 which is essentially the same badge as Royal Flying Corps

Royal Flying Corps

The Royal Flying Corps was the over-land air arm of the British military during most of the First World War. During the early part of the war, the RFC's responsibilities were centred on support of the British Army, via artillery co-operation and photographic reconnaissance...

sergeants wore. Between 1950 and 1964 the badge was three point up chevrons below a crown.