Nehézségi fok: NEHÉZ
“Piper G-BTKX squawk 3026”. In this case, squawk means turn your transponder on, not squawk like a bird. Squawk originates from “squawk your parrot”, which was used in WW2 by the British. In 1939 the first transponder was put into operation, and it was called the Parrot. The Parrot was a code name for Mark I which was a British radio transponder system that was created to identify British aeroplanes.
It was a simple system that amplified the signals of the radar, causing the aircraft’s blip to extend on the operator’s radar display, identifying the aircraft as friendly. However, Mark I had the problem that the gain had to be adjusted in flight to keep it working and in the field it was correct only half the time. After a short run of the experimental prototype Mark I, the Mark II began widespread deployment in late 1940. It remained in use until 1943 when it began to be replaced by the standardised MARK III, which was used by all Allied aircraft until long after the war ended.
The need to identify their own was because when they were returning home from night missions at the end of WWII German aircraft would join into their formation. The parrot was a great solution, and the British became the first to develop Radio Frequency Identification (RFID). It would reply to a radar interrogating signal by responding with a coded transmission. A code would allow the land-based radar station to distinguish British from German aircraft on their radar screen. The transponder also contained an internal thermite bomb which, when triggered by an inertial switch (in case of crash), would destroy the interior of the set. This was supposed to prevent German discovery of the codes.
Nevertheless, there was a problem. The parrot was covering up radio operations. The intensive power of the transponder signal would often hide other targets as well. To control the operation of the airborne coded set to the best advantage, the ground-based radar station would give radio instructions regarding the operation of the airborne equipment. British pilots would only turn their parrot on when told by radio operations, “squawk your parrot”. Once identified, the operator would say “strangle your parrot”, meaning turn your transponder off.
Before the parrot there was a way of detecting aircraft, however, it was a passive system that worked off of metal by reflecting signals. This radar system was called primary radar, and this is what lead to the invention of Radio Frequency Identification (RFID) and the transponder later. The primary radar was for tackling the same task such as showing where aircraft were located as the parrot did. However, it worked off of a radar signal that was bounced off of the metal parts of aircraft. This came with problems, such as most small aeroplanes at the time had only engines made of metal. Terrain and the environment got in the way of the radar range, and the system often detected unwanted objects like vehicles on the ground. When two aircraft got relatively close there just seemed to be a big blur picked up by the radio operator. It was also quite sensitive to weather. This error in the primary radar leads to Secondary Surveillance Radar (SSR) or Radio Frequency Identification (RFID) which depends on a transponder in the aircraft to respond to interrogated radar signals from ground stations.
A transponder system is also referred to as Identification Friend or Foe (IFF). The transponder is short for transmitter- responder and has not changed much as far as how it works since WWII.
The only vestige of this that remains today, other than the entire ATC system itself, is the term “squawk”, as a directive for operation or code for the transponder. Old-time air traffic controllers may still have you strangle your parrot.
Not long after WWII an American transport aircraft was inbound to the UK. An RAF radar station asked the pilot if he had Parrot on board. There was a long pause and then came the reply ” No sir, but we have a bird colonel if he’s any use to you”.
RADAR SCREEN RADARKÉPERNYŐ
THERMITE BOMB TERMIT BOMBA
INERTIAL SWITCH TEHETETLENSÉGI KAPCSOLÓ
COVER UP BEFED
AIRBORNE EQUIPMENT FEDÉLZETI BERENDEZÉS
PRIMARY RADAR ELSŐDLEGES RADAR
TACKLE THE TASK MEGBIRKÓZIK A FELADATTAL
SECONDARY SURVEILLANCE RADAR MÁSODLAGOS LÉGTÉRELLENŐRZŐ RADAR
BIRD COLONEL EZREDES