Apparatus

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sensors Mode-S transponder

4BAB21

ICAO 24-bit transponder address · allocated to Turkey

Currently assigned to TC-JYA · BOEING 737-900

Hex
4BAB21
Octal
22725441
Decimal
4,959,009
Country
TR
Tail
TC-JYA
Type
B739
Broadcasting now · callsign THY1145 · 30,225 ft
Flights observed
184
Distinct callsigns
20
Country
TR
Last broadcast
12h ago

Current position

4BAB21 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address 4BAB21 falls within the block assigned to Turkey (TR) by ICAO Annex 10, Volume III. Every aircraft registered in Turkey receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 20 distinct

Callsign Airline Flights Last seen
THY1VN - 8 2026-06-14
THY9QS - 6 2026-06-14
THY9GY - 4 2026-06-14
THY8RJ - 4 2026-05-12
THY4GL Turkish Airlines 4 2026-06-14
THY4AV - 4 2026-06-12
THY1140 - 4 2026-06-20
THY1139 - 4 2026-06-20
THY8GS Turkish Airlines 3 2026-06-12
THY7SP - 3 2026-06-19
THY6BW - 3 2026-06-22
THY2XK Turkish Airlines 3 2026-06-14
THY2GS Turkish Airlines 3 2026-05-28
THY1TU - 3 2026-06-19
THY9UH Turkish Airlines 2 2026-05-26
THY8YA - 2 2026-06-15
THY8NY Turkish Airlines 2 2026-06-07
THY8CJ Turkish Airlines 2 2026-05-26
THY6RZ Turkish Airlines 2 2026-06-18
THY6JV Turkish Airlines 2 2026-06-01

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-24 THY7PY - Jun 24, 17:45 UTCJun 24, 21:04 UTC3h 20m
2026-06-24 THY1XL - Jun 24, 12:30 UTCJun 24, 15:44 UTC3h 15m
2026-06-24 THY2CV - Jun 24, 07:20 UTCJun 24, 08:35 UTC1h 15m
2026-06-24 THY4YJ - Jun 24, 04:50 UTCJun 24, 06:04 UTC1h 15m
2026-06-23 THY7WH - Jun 23, 22:10 UTCJun 24, 02:15 UTC4h 5m
2026-06-23 THY3KY - Jun 23, 16:59 UTCJun 23, 19:19 UTC2h 20m
2026-06-23 THY8UG ADA → BEY Jun 23, 13:09 UTCJun 23, 15:40 UTC2h 30m
2026-06-23 THY642 - Jun 23, 08:20 UTCJun 23, 09:59 UTC1h 40m
2026-06-23 THY641 - Jun 23, 04:09 UTCJun 23, 05:59 UTC1h 50m
2026-06-23 THY88C - Jun 23, 00:45 UTCJun 23, 01:20 UTC35m
2026-06-22 THY7WG IST → VAR Jun 22, 23:10 UTCJun 22, 23:39 UTC30m
2026-06-22 THY6BW - Jun 22, 16:05 UTCJun 22, 17:00 UTC55m
2026-06-22 THY2PX CND → IST Jun 22, 13:25 UTCJun 22, 14:19 UTC55m
2026-06-22 THY3DU - Jun 22, 10:10 UTCJun 22, 11:00 UTC50m
2026-06-22 THY95M - Jun 22, 08:04 UTCJun 22, 08:50 UTC45m
2026-06-22 THY9QW - Jun 22, 05:40 UTCJun 22, 06:29 UTC50m
2026-06-22 THY8SA - Jun 22, 03:24 UTCJun 22, 04:09 UTC45m
2026-06-21 THY5RC - Jun 21, 23:24 UTCJun 22, 00:10 UTC45m
2026-06-21 THY4KZ NCE → IST Jun 21, 17:05 UTCJun 21, 17:29 UTC25m
2026-06-21 THY1LA MXP → IST Jun 21, 14:24 UTCJun 21, 14:54 UTC30m
2026-06-21 THY6WQ - Jun 21, 08:44 UTCJun 21, 11:15 UTC2h 30m
2026-06-21 THY6XK - Jun 21, 05:10 UTCJun 21, 07:29 UTC2h 20m
2026-06-20 THY1140 - Jun 20, 17:54 UTCJun 20, 20:20 UTC2h 25m
2026-06-20 THY1139 - Jun 20, 13:19 UTCJun 20, 15:34 UTC2h 15m
2026-06-20 THY642 - Jun 20, 03:59 UTCJun 20, 09:34 UTC5h 35m
2026-06-19 THY1TU - Jun 19, 18:44 UTCJun 19, 20:19 UTC1h 35m
2026-06-19 THY7SP - Jun 19, 15:49 UTCJun 19, 17:19 UTC1h 30m
2026-06-19 THY5UW - Jun 19, 12:04 UTCJun 19, 13:44 UTC1h 40m
2026-06-19 THY4HU - Jun 19, 08:44 UTCJun 19, 10:35 UTC1h 50m
2026-06-18 THY2QT - Jun 18, 17:21 UTCJun 18, 17:50 UTC29m
2026-06-18 THY6RZ WAW → IST Jun 18, 15:55 UTCJun 18, 16:10 UTC15m
2026-06-18 THY6RZ WAW → IST Jun 18, 14:50 UTCJun 18, 15:10 UTC20m
2026-06-18 THY1QU - Jun 18, 08:40 UTCJun 18, 12:05 UTC3h 25m
2026-06-18 THY7MV - Jun 18, 05:50 UTCJun 18, 06:45 UTC55m
2026-06-18 THY2TF - Jun 18, 03:45 UTCJun 18, 04:40 UTC55m
2026-06-17 THY1ZY - Jun 17, 18:35 UTCJun 17, 19:20 UTC45m
2026-06-17 THY6GR - Jun 17, 16:35 UTCJun 17, 17:25 UTC50m
2026-06-17 THY1WL - Jun 17, 08:20 UTCJun 17, 11:35 UTC3h 15m
2026-06-16 THY3XM - Jun 16, 15:05 UTCJun 16, 18:25 UTC3h 20m
2026-06-16 THY4YL - Jun 16, 08:10 UTCJun 16, 08:55 UTC45m
2026-06-16 THY3UZ - Jun 16, 05:15 UTCJun 16, 05:45 UTC30m
2026-06-15 THY6BW - Jun 15, 13:34 UTCJun 15, 17:15 UTC3h 40m
2026-06-15 THY3HM - Jun 15, 07:29 UTCJun 15, 10:50 UTC3h 20m
2026-06-15 THY7GJ - Jun 15, 02:50 UTCJun 15, 03:50 UTC1h 0m
2026-06-15 THY8YA - Jun 15, 00:35 UTCJun 15, 01:00 UTC25m
2026-06-14 THY8YA - Jun 14, 23:05 UTCJun 14, 23:35 UTC29m
2026-06-14 THY2XK GZT → IST Jun 14, 15:50 UTCJun 14, 19:45 UTC3h 55m
2026-06-14 THY4GL TZX → IST Jun 14, 12:10 UTCJun 14, 13:45 UTC1h 35m
2026-06-14 THY9GY - Jun 14, 09:10 UTCJun 14, 11:00 UTC1h 50m
2026-06-14 THY1VN - Jun 14, 07:10 UTCJun 14, 07:30 UTC20m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the TC-JYA page for operator, model, and routing details .

Mode-S 4BAB21 frequently asked

What is Mode-S code 4BAB21?
4BAB21 is an ICAO 24-bit transponder address. Allocated to Turkey. Assigned to TC-JYA.
Where is Mode-S 4BAB21 registered?
Mode-S code 4BAB21 is allocated to Turkey (TR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4BAB21 broadcasting right now?
Yes. Mode-S 4BAB21 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4BAB21, octal 22725441, decimal 4,959,009.
What flights does 4BAB21 operate?
Mode-S 4BAB21 has broadcast 20 distinct callsigns, including THY1VN, THY9QS, THY9GY, THY8RJ, THY4GL.