Apparatus

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sensors Mode-S transponder

4C0221

ICAO 24-bit transponder address · allocated to Serbia

Currently assigned to YU-ARB · AIRBUS A-330-200

Hex
4C0221
Octal
23001041
Decimal
4,981,281
Country
RS
Tail
YU-ARB
Type
A332
Broadcasting now · callsign ASL500 · 36,000 ft
Flights observed
119
Distinct callsigns
6
Country
RS
Last broadcast
54m ago

Current position

4C0221 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address 4C0221 falls within the block assigned to Serbia (RS) by ICAO Annex 10, Volume III. Every aircraft registered in Serbia 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 6 distinct

Callsign Airline Flights Last seen
ASL500 - 43 2026-07-14
ASL501 - 39 2026-07-13
ASL509 - 10 2026-07-12
ASL508 - 9 2026-07-11
ASL507 - 9 2026-07-08
ASL506 - 9 2026-07-08

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 ASL500 - Jul 14, 06:15 UTCJul 14, 08:15 UTC2h 0m
2026-07-13 ASL501 JFK → BEG Jul 13, 18:30 UTCJul 14, 02:45 UTC8h 15m
2026-07-13 ASL500 BEG → JFK Jul 13, 06:20 UTCJul 13, 15:30 UTC9h 10m
2026-07-12 ASL509 - Jul 12, 01:00 UTCJul 12, 07:55 UTC6h 55m
2026-07-11 ASL509 - Jul 11, 23:25 UTCJul 12, 00:50 UTC1h 25m
2026-07-11 ASL508 BEG → YYZ Jul 11, 11:25 UTCJul 11, 20:45 UTC9h 20m
2026-07-09 ASL501 JFK → BEG Jul 9, 23:50 UTCJul 10, 08:00 UTC8h 10m
2026-07-09 ASL500 BEG → JFK Jul 9, 11:50 UTCJul 9, 21:10 UTC9h 20m
2026-07-08 ASL507 ORD → BEG Jul 8, 22:50 UTCJul 9, 07:55 UTC9h 5m
2026-07-08 ASL506 BEG → ORD Jul 8, 09:20 UTCJul 8, 20:10 UTC10h 50m
2026-07-07 ASL501 JFK → BEG Jul 7, 18:45 UTCJul 8, 02:50 UTC8h 5m
2026-07-07 ASL500 BEG → JFK Jul 7, 06:45 UTCJul 7, 16:00 UTC9h 15m
2026-07-06 ASL501 JFK → BEG Jul 6, 18:35 UTCJul 7, 02:20 UTC7h 45m
2026-07-06 ASL500 BEG → JFK Jul 6, 06:10 UTCJul 6, 15:45 UTC9h 35m
2026-07-04 ASL509 YYZ → BEG Jul 4, 23:50 UTCJul 5, 07:55 UTC8h 5m
2026-07-04 ASL508 BEG → YYZ Jul 4, 11:10 UTCJul 4, 20:50 UTC9h 40m
2026-07-03 ASL501 JFK → BEG Jul 3, 00:35 UTCJul 3, 08:20 UTC7h 45m
2026-07-02 ASL500 BEG → JFK Jul 2, 11:55 UTCJul 2, 21:25 UTC9h 30m
2026-07-01 ASL507 - Jul 1, 22:30 UTCJul 2, 07:10 UTC8h 40m
2026-07-01 ASL506 BEG → ORD Jul 1, 08:50 UTCJul 1, 19:25 UTC10h 35m
2026-06-30 ASL501 - Jun 30, 18:10 UTCJul 1, 02:10 UTC8h 0m
2026-06-30 ASL500 BEG → JFK Jun 30, 06:10 UTCJun 30, 15:05 UTC8h 55m
2026-06-29 ASL501 - Jun 29, 18:14 UTCJun 30, 02:20 UTC8h 6m
2026-06-29 ASL500 BEG → JFK Jun 29, 06:09 UTCJun 29, 15:19 UTC9h 10m
2026-06-27 ASL509 - Jun 27, 23:25 UTCJun 28, 07:40 UTC8h 15m
2026-06-27 ASL508 BEG → YYZ Jun 27, 10:50 UTCJun 27, 19:55 UTC9h 5m
2026-06-23 ASL501 JFK → BEG Jun 23, 18:29 UTCJun 24, 02:34 UTC8h 5m
2026-06-23 ASL500 BEG → JFK Jun 23, 06:15 UTCJun 23, 15:55 UTC9h 40m
2026-06-22 ASL501 JFK → BEG Jun 22, 19:09 UTCJun 23, 03:15 UTC8h 5m
2026-06-22 ASL500 BEG → JFK Jun 22, 06:29 UTCJun 22, 15:45 UTC9h 15m
2026-06-21 ASL509 YYZ → BEG Jun 21, 01:55 UTCJun 21, 10:19 UTC8h 25m
2026-06-20 ASL508 BEG → YYZ Jun 20, 14:05 UTCJun 20, 23:14 UTC9h 10m
2026-06-19 ASL501 JFK → BEG Jun 19, 00:49 UTCJun 19, 09:04 UTC8h 15m
2026-06-18 ASL500 BEG → JFK Jun 18, 12:05 UTCJun 18, 21:40 UTC9h 35m
2026-06-16 ASL501 JFK → BEG Jun 16, 18:20 UTCJun 17, 02:05 UTC7h 46m
2026-06-16 ASL500 BEG → JFK Jun 16, 06:15 UTCJun 16, 15:35 UTC9h 20m
2026-06-15 ASL501 JFK → BEG Jun 15, 18:40 UTCJun 16, 02:34 UTC7h 55m
2026-06-15 ASL500 BEG → JFK Jun 15, 06:30 UTCJun 15, 16:15 UTC9h 45m
2026-06-13 ASL509 YYZ → BEG Jun 13, 23:15 UTCJun 14, 07:20 UTC8h 5m
2026-06-13 ASL508 BEG → YYZ Jun 13, 10:50 UTCJun 13, 20:20 UTC9h 30m
2026-06-12 ASL501 JFK → BEG Jun 12, 00:50 UTCJun 12, 08:55 UTC8h 5m
2026-06-11 ASL500 BEG → JFK Jun 11, 11:55 UTCJun 11, 21:10 UTC9h 15m
2026-06-10 ASL507 ORD → BEG Jun 10, 22:50 UTCJun 11, 07:50 UTC9h 0m
2026-06-10 ASL506 BEG → ORD Jun 10, 08:50 UTCJun 10, 18:55 UTC10h 5m
2026-06-09 ASL501 JFK → BEG Jun 9, 20:25 UTCJun 10, 02:05 UTC5h 40m
2026-06-09 ASL500 BEG → JFK Jun 9, 06:30 UTCJun 9, 15:50 UTC9h 20m
2026-06-08 ASL501 JFK → BEG Jun 8, 18:30 UTCJun 9, 02:30 UTC8h 0m
2026-06-08 ASL500 BEG → JFK Jun 8, 09:10 UTCJun 8, 15:04 UTC5h 55m
2026-06-08 ASL500 BEG → JFK Jun 8, 06:05 UTCJun 8, 09:05 UTC3h 0m
2026-06-06 ASL509 YYZ → BEG Jun 6, 23:09 UTCJun 7, 07:20 UTC8h 10m

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 YU-ARB page for operator, model, and routing details .

Mode-S 4C0221 frequently asked

What is Mode-S code 4C0221?
4C0221 is an ICAO 24-bit transponder address. Allocated to Serbia. Assigned to YU-ARB.
Where is Mode-S 4C0221 registered?
Mode-S code 4C0221 is allocated to Serbia (RS). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4C0221 broadcasting right now?
Yes. Mode-S 4C0221 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4C0221, octal 23001041, decimal 4,981,281.
What flights does 4C0221 operate?
Mode-S 4C0221 has broadcast 6 distinct callsigns, including ASL500, ASL501, ASL509, ASL508, ASL507.