What does squak mean?

[gmclam]

Today I spent a lot of time at an airport and had my scanner running the entire time. I noticed a term I hadn't heard before - the message would be squak and a 4 digit number. It seems like a transponder code or something. Can someone please set me straight?

Thanks,
George

 

[wesm1957]

That's just what it is. The pilot sets the transponder with the numbers the control tower gives them and pushes a button on the transponder. The numbers are actually an AM frequiency. The transponder transmitts info to the reciever and puts the plane on the towers radar screen. I had a friend that was a pilot and flew with him many times in a Cessna, and he showed me that every time the radar beam hit the plane there was a light on the transponder that would light up.

Wes

 

[gmclam]

Thank you

Thank you very much

 

[crayon]

Some other tid bits of info ..

Interrogation pulses are at 1030 MHz and the reply pulses from the aircraft are at a 1090 MHz. If I remember correctly, the pulse train is BCD.

A VFR aircraft should have 1200 entered as its squak code.

You only "push the button" when a controller tells you to ident. What that does is make your stand out on the radar scope so he can see you amongst everyone else.

 

[epbernstein]

"Squawk" comes from the idea of a parrot--one says something to the bird, and the bird repeats it. The transponder was developed during WW II to differentiate friendly from enemy aircraft. Another term for it is "IFF," which stands for "Identify--Friend or Foe." The button that is pushed is called the "ident," or "Identify" button.

An interesting thing about transponders is that they use octal codes--that is, the usable codes range from 0000 to 7777, with no 8's or 9's. You don't want to use any codes that are in the "00XX" range, and you'd better have a good reason for using any "77XX" codes; those are reserved for certain types of emergencies.

 

[morfis]

Codes vary from region to region (except the emergency type ones).

7700................Special Purpose Code - Emergency
7776-7777.......SSR Monitors

Other 77xx are special use but not necessarily emergency-related IIRC

 

[Colin9690]

Some special use transponder codes are:

1200- Standard VFR code.
1205- Used for transitioning special airspace around Washington DC.
7500- Aircraft is being hijacked
7600- Loss of radio communication
7700- General emergency

All the 7xxx series codes trigger a special alarm at all radar facilities in range of the transponder when entered into the unit.

 

[Yokoshibu]

The numbers are actually an AM frequiency. The transponder transmitts info to the reciever and puts the plane on the towers radar screen. I had a friend that was a pilot and flew with him many times in a Cessna, and he showed me that every time the radar beam hit the plane there was a light on the transponder that would light up.

Wes

uhm not an AM freq....

and 7777 .... I didnt know it was a ssr squak..... I know it as something else in the states.

 

[kicktd]

taken from http://en.wikipedia.org/wiki/Transponder_code

Routine codes

* 1200: Visual flight rules (VFR) flight, this is the standard squawk code used in North American airspace when no other has been assigned.
* 7000: VFR standard squawk code for most European airspace when no other code has been assigned.
* 7004: Aerobatic and display code.
* 0021: VFR squawk code for German airspace (5000 feet and below)
* 0022: VFR squawk code for German airspace (above 5000 feet)
* 0001: Military code for highspeed uncontrolled (non-ATC directed) flight (US)
* 7001: Sudden military climbout from low-level operations (UK)
* 2000: The code to be squawked when entering a secondary surveillance radar (SSR) area from a non-SSR area (used as a VFR squawk code in some European countries)
* 0000: military escort (in the US), suspected transponder failure (in the UK).
* 7777: military interception (US/FAA)

"Under no circumstances should a pilot of a civil aircraft operate the transponder on Code 7777. This code is reserved for military interceptor operations."

Emergency codes

* 7700: Emergency
* 7600: Lost Communications
* 7500: Hijack (Unlawful Interference)

 

[morfis]

The full lists for each country are contained in the relevant AIP documents. These are usually available online. In the Uk case the required document is ENR 1-6-2-8 available from: http://www.ais.org.uk