General – Squawk Codes And Transponders

A squawk code is a 4-digit code ranging from 0000 to 7777. They are used by ATC to identify aircraft. The transponder is the equipment in the cockpit that sends and receives the data.

Transponders

Mode A

Is the most basic transponder mode, it only transmits the four-digit squawk code.

Mode C

Is the most widely used transponder mode.

Mode C provides information on the aircraft pressure Altitude. Combined with mode A, ATC and other aircraft receive an aircraft-unique squawk code, position and altitude.

The combination of modes A and C is normally just referred to as mode C.

Mode S

Mode S, short for “Mode Select” is a type of transponder that offers more advanced communication capabilities than a mode A or mode C transponder.

When you use a mode C transponder, it transmits a variety of valuable information to ATC and other aircraft.
Unique ICAO address: Every aircraft has a unique ICAO address assigned to it, Mode S transponders send this address, which helps ATC and other aircraft identify your specific aircraft.
Squawk Code: Just like mode A, mode S transponders also transmit the four-digit squawk code assigned by ATC.
Altitude: Similar to mode C, mode S transponders provide your aircraft altitude.
Position, Speed, Heading: Mode S transponders can also send your aircraft GPS-based position, speed, and heading, which helps ATC and nearby aircraft know your location and direction of travel.
Additional Flight-Related Data: Depending on the transponder’s capabilities, it can transmit other flight-related information such as your autopilot heading.

Ident

ATC may request you squawk ident, this will make you easy to find on their radar screen, if this happens you simply push the button.

Restrictions

Mode S is required for aircraft.
Within class A or C airspace.
Above FL100 or
Within transponder mandatory zones = (TMZ) (Stansted TMZ)
Aircraft without Mode S may enter a TMZ with the approval of ATC.

Squawk Codes

7700Emergency code
7600Radio Failure
7500Unlawful Interference/Hijack – NOT PERMITTED ON IVAO
0030Lost
2000IFR code
7000VFR code

Listening Squak Codes

Frequency Monitoring codes (FMC) should be selected on your aircraft transponder while monitoring the applicable ATC frequency, without having to establish radio communication.
Remember to return your transponder to the appropriate conspicuity code VFR 7000 when the relevant frequency is no longer being monitored.

Note you still need to contact ATC if you plan on entering controlled airspace, use of these codes DOES NOT permit you to not contact ATC, the codes are to show you are monitoring if you are going around the edge of controlled airspace or flying close to it.

Aberdeen Dyce4270119.055
Glasgow2620119.100
Edinburgh0440121.205
Newcastle3737124.380
Belfast Aldergrove8045133.125
Belfast City4255130.850
Leeds Bradford2677134.580
Warton3660129.530
Liverpool5060119.855
Hawarden4607*120.055
Manchester7366118.580
East Midlands4572134.180
Birmingham0010123.980
Norwich7350119.355
Stansted7013120.625
Luton0013129.550
Oxford4517125.090
Southend5050120.625
Thames=Heathrow and City0012132.700
Bristol5077125.650
Cardiff3636119.155
Farnborough4572125.250
Gatwick7012126.825
Bournemouth0011119.480
Southampton7011120.230
Not to be used for real world aviation.