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sensors Mode-S transponder

4A1921

ICAO 24-bit transponder address · allocated to Romania

Currently assigned to YR-FIA · AIRBUS A-320

Hex
4A1921
Octal
22414441
Decimal
4,856,097
Country
RO
Tail
YR-FIA
Type
A320
No current signal · last broadcast 4d ago
Flights observed
135
Distinct callsigns
20
Country
RO
Last broadcast
4d ago

Last known position

Most recent position reported by Mode-S 4A1921.

Country allocation

The ICAO 24-bit address 4A1921 falls within the block assigned to Romania (RO) by ICAO Annex 10, Volume III. Every aircraft registered in Romania 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
FOE7501 - 28 2026-06-19
FOE7502 - 27 2026-06-19
FOE7096 - 9 2026-06-14
FOE7095 - 8 2026-06-14
FOE8442 - 7 2026-06-13
FOE8441 - 5 2026-06-11
FOE8429 - 5 2026-06-13
NIA192 Nile Air 2 2026-07-13
NIA191 - 2 2026-07-13
FOE8430 - 2 2026-05-16
NIA9102 - 1 2026-07-08
NIA8604 - 1 2026-07-11
NIA8603 - 1 2026-07-11
NIA8601 - 1 2026-07-10
NIA851 - 1 2026-07-10
NIA174 - 1 2026-07-10
NIA173 - 1 2026-07-10
HYS8311 - 1 2026-06-17
HYS7694 - 1 2026-06-06
HYS7693 - 1 2026-06-06

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 NIA192 SAW → CAI Jul 13, 15:30 UTCJul 13, 17:20 UTC1h 50m
2026-07-13 NIA191 - Jul 13, 10:30 UTCJul 13, 12:00 UTC1h 30m
2026-07-12 NIA192 SAW → CAI Jul 12, 13:30 UTCJul 12, 15:10 UTC1h 40m
2026-07-12 NIA191 - Jul 12, 10:25 UTCJul 12, 11:55 UTC1h 30m
2026-07-11 NIA8604 - Jul 11, 22:35 UTCJul 12, 05:50 UTC7h 15m
2026-07-11 NIA8603 BER → ERF Jul 11, 10:55 UTCJul 11, 21:20 UTC10h 25m
2026-07-10 NIA8601 - Jul 10, 20:45 UTCJul 11, 09:35 UTC12h 50m
2026-07-10 NIA851 - Jul 10, 12:50 UTCJul 10, 19:20 UTC6h 30m
2026-07-10 NIA174 - Jul 10, 07:10 UTCJul 10, 10:20 UTC3h 10m
2026-07-10 NIA173 - Jul 10, 02:05 UTCJul 10, 05:40 UTC3h 35m
2026-07-08 NIA9102 - Jul 8, 10:50 UTCJul 8, 13:00 UTC2h 10m
2026-06-28 AWG611 - Jun 28, 12:29 UTCJun 28, 15:14 UTC2h 45m
2026-06-28 AWG610 - Jun 28, 07:54 UTCJun 28, 10:30 UTC2h 35m
2026-06-27 AWG6003 - Jun 27, 15:05 UTCJun 27, 15:39 UTC35m
2026-06-27 AWG4209 - Jun 27, 06:05 UTCJun 27, 13:44 UTC7h 40m
2026-06-19 FOE7502 BRU → OTP Jun 19, 18:54 UTCJun 19, 21:19 UTC2h 25m
2026-06-19 FOE7501 - Jun 19, 15:14 UTCJun 19, 17:44 UTC2h 30m
2026-06-18 HYS021P - Jun 18, 19:05 UTCJun 18, 19:40 UTC35m
2026-06-18 HYS5472 - Jun 18, 16:00 UTCJun 18, 18:05 UTC2h 5m
2026-06-18 HYS5471 - Jun 18, 12:25 UTCJun 18, 14:35 UTC2h 10m
2026-06-18 HYS278 - Jun 18, 10:50 UTCJun 18, 11:15 UTC25m
2026-06-18 HYS7442 - Jun 18, 08:00 UTCJun 18, 09:25 UTC1h 25m
2026-06-18 HYS7441 - Jun 18, 05:05 UTCJun 18, 06:25 UTC1h 20m
2026-06-17 HYS8311 - Jun 17, 07:50 UTCJun 17, 16:35 UTC8h 45m
2026-06-16 AWG4127 RHO → OTP Jun 16, 18:55 UTCJun 16, 20:30 UTC1h 36m
2026-06-16 AWG4126 OTP → RHO Jun 16, 16:10 UTCJun 16, 17:49 UTC1h 40m
2026-06-16 AWG4133 HER → OTP Jun 16, 13:34 UTCJun 16, 14:55 UTC1h 20m
2026-06-16 AWG4134 IAS → HER Jun 16, 09:40 UTCJun 16, 11:30 UTC1h 50m
2026-06-16 AWG4135 HER → IAS Jun 16, 06:54 UTCJun 16, 08:25 UTC1h 30m
2026-06-16 AWG4132 OTP → HER Jun 16, 03:55 UTCJun 16, 05:20 UTC1h 25m
2026-06-15 FOE7502 - Jun 15, 09:40 UTCJun 15, 11:54 UTC2h 15m
2026-06-15 FOE7501 OTP → BRU Jun 15, 04:25 UTCJun 15, 07:05 UTC2h 40m
2026-06-14 FOE7096 - Jun 14, 19:30 UTCJun 14, 22:05 UTC2h 35m
2026-06-14 FOE7095 - Jun 14, 15:20 UTCJun 14, 18:35 UTC3h 15m
2026-06-13 FOE8442 - Jun 13, 09:25 UTCJun 13, 13:40 UTC4h 15m
2026-06-13 FOE8429 - Jun 13, 00:25 UTCJun 13, 07:45 UTC7h 19m
2026-06-12 FOE7502 - Jun 12, 16:10 UTCJun 12, 18:15 UTC2h 5m
2026-06-12 FOE7501 - Jun 12, 12:20 UTCJun 12, 14:50 UTC2h 30m
2026-06-11 FOE8442 - Jun 11, 05:10 UTCJun 11, 06:40 UTC1h 30m
2026-06-11 FOE8441 - Jun 11, 02:35 UTCJun 11, 04:00 UTC1h 25m
2026-06-10 FOE7502 BRU → OTP Jun 10, 17:35 UTCJun 10, 19:55 UTC2h 20m
2026-06-10 FOE7501 - Jun 10, 13:25 UTCJun 10, 15:55 UTC2h 30m
2026-06-10 FOE7096 - Jun 10, 09:10 UTCJun 10, 11:55 UTC2h 45m
2026-06-10 FOE7095 - Jun 10, 04:35 UTCJun 10, 07:35 UTC3h 0m
2026-06-08 FOE8442 - Jun 8, 15:10 UTCJun 8, 16:40 UTC1h 30m
2026-06-08 FOE8441 - Jun 8, 12:15 UTCJun 8, 13:50 UTC1h 35m
2026-06-08 FOE7502 - Jun 8, 08:10 UTCJun 8, 10:25 UTC2h 15m
2026-06-08 FOE7501 - Jun 8, 04:15 UTCJun 8, 06:50 UTC2h 35m
2026-06-07 FOE7096 - Jun 7, 11:55 UTCJun 7, 14:35 UTC2h 40m
2026-06-07 FOE7095 - Jun 7, 07:30 UTCJun 7, 10:40 UTC3h 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 YR-FIA page for operator, model, and routing details .

Mode-S 4A1921 frequently asked

What is Mode-S code 4A1921?
4A1921 is an ICAO 24-bit transponder address. Allocated to Romania. Assigned to YR-FIA.
Where is Mode-S 4A1921 registered?
Mode-S code 4A1921 is allocated to Romania (RO). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4A1921 broadcasting right now?
No active broadcast right now. Last signal was 4d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4A1921, octal 22414441, decimal 4,856,097.
What flights does 4A1921 operate?
Mode-S 4A1921 has broadcast 20 distinct callsigns, including FOE7501, FOE7502, FOE7096, FOE7095, FOE8442.