Apparatus

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sensors Mode-S transponder

4520FB

ICAO 24-bit transponder address · allocated to Bulgaria

Currently assigned to LZ-GPA · BOEING 737-400

Hex
4520FB
Octal
21220373
Decimal
4,530,427
Country
BG
Tail
LZ-GPA
Type
B734
No current signal · last broadcast 6h ago
Flights observed
183
Distinct callsigns
16
Country
BG
Last broadcast
6h ago

Last known position

Most recent position reported by Mode-S 4520FB.

Country allocation

The ICAO 24-bit address 4520FB falls within the block assigned to Bulgaria (BG) by ICAO Annex 10, Volume III. Every aircraft registered in Bulgaria 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 16 distinct

Callsign Airline Flights Last seen
GPX601 GP Aviation 33 2026-05-28
GPX600 GP Aviation 33 2026-05-28
GPX701 GP Aviation 25 2026-05-29
GPX700 GP Aviation 23 2026-05-29
GPX2MI GP Aviation 12 2026-05-29
GPX602 GP Aviation 11 2026-05-23
GPX2IM GP Aviation 11 2026-05-29
GPX603 GP Aviation 10 2026-05-23
GPX1LB GP Aviation 6 2026-05-25
GPX1BL GP Aviation 6 2026-05-25
GPX802 GP Aviation 3 2026-04-18
GPX3XJ - 3 2026-05-24
GPX3JX - 3 2026-05-24
GPX803 GP Aviation 2 2026-04-18
GPX1805 - 1 2026-04-23
GPX1804 - 1 2026-04-23

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-05-29 GPX2IM BSL → PRN May 29, 18:30 UTCMay 29, 20:05 UTC1h 35m
2026-05-29 GPX2MI PRN → BSL May 29, 16:00 UTCMay 29, 17:35 UTC1h 35m
2026-05-29 GPX701 GVA → PRN May 29, 12:35 UTCMay 29, 14:15 UTC1h 40m
2026-05-29 GPX700 PRN → GVA May 29, 09:10 UTCMay 29, 10:55 UTC1h 45m
2026-05-28 GPX601 ZRH → PRN May 28, 18:30 UTCMay 28, 19:55 UTC1h 25m
2026-05-28 GPX600 PRN → ZRH May 28, 15:50 UTCMay 28, 17:25 UTC1h 35m
2026-05-27 GPX601 ZRH → PRN May 27, 18:30 UTCMay 27, 20:00 UTC1h 30m
2026-05-27 GPX600 PRN → ZRH May 27, 15:35 UTCMay 27, 17:20 UTC1h 45m
2026-05-27 GPX701 GVA → PRN May 27, 12:10 UTCMay 27, 13:50 UTC1h 40m
2026-05-27 GPX700 PRN → GVA May 27, 09:05 UTCMay 27, 10:55 UTC1h 50m
2026-05-26 GPX601 ZRH → PRN May 26, 18:30 UTCMay 26, 20:05 UTC1h 35m
2026-05-26 GPX600 PRN → ZRH May 26, 15:39 UTCMay 26, 17:20 UTC1h 40m
2026-05-25 GPX601 ZRH → PRN May 25, 18:30 UTCMay 25, 19:59 UTC1h 30m
2026-05-25 GPX600 PRN → ZRH May 25, 15:50 UTCMay 25, 17:25 UTC1h 35m
2026-05-25 GPX1LB BSL → PRN May 25, 13:00 UTCMay 25, 14:35 UTC1h 35m
2026-05-25 GPX1BL PRN → BSL May 25, 10:00 UTCMay 25, 11:35 UTC1h 35m
2026-05-24 GPX601 ZRH → PRN May 24, 18:40 UTCMay 24, 20:20 UTC1h 40m
2026-05-24 GPX600 PRN → ZRH May 24, 15:35 UTCMay 24, 17:10 UTC1h 35m
2026-05-24 GPX701 GVA → PRN May 24, 12:10 UTCMay 24, 13:55 UTC1h 45m
2026-05-24 GPX700 PRN → GVA May 24, 08:50 UTCMay 24, 10:40 UTC1h 50m
2026-05-24 GPX3XJ - May 24, 05:15 UTCMay 24, 07:10 UTC1h 55m
2026-05-24 GPX3JX - May 24, 01:35 UTCMay 24, 03:50 UTC2h 15m
2026-05-23 GPX603 ZRH → PRN May 23, 19:10 UTCMay 23, 20:35 UTC1h 25m
2026-05-23 GPX602 PRN → ZRH May 23, 17:25 UTCMay 23, 17:45 UTC20m
2026-05-23 GPX602 PRN → ZRH May 23, 16:05 UTCMay 23, 17:20 UTC1h 15m
2026-05-23 GPX1LB BSL → PRN May 23, 12:55 UTCMay 23, 14:30 UTC1h 35m
2026-05-23 GPX1BL PRN → BSL May 23, 10:00 UTCMay 23, 11:45 UTC1h 45m
2026-05-22 GPX601 ZRH → PRN May 22, 18:35 UTCMay 22, 20:05 UTC1h 30m
2026-05-22 GPX600 PRN → ZRH May 22, 15:40 UTCMay 22, 17:20 UTC1h 40m
2026-05-22 GPX701 GVA → PRN May 22, 12:15 UTCMay 22, 14:00 UTC1h 45m
2026-05-22 GPX700 PRN → GVA May 22, 09:05 UTCMay 22, 10:50 UTC1h 45m
2026-05-21 GPX601 ZRH → PRN May 21, 18:40 UTCMay 21, 20:15 UTC1h 35m
2026-05-21 GPX600 PRN → ZRH May 21, 15:35 UTCMay 21, 17:20 UTC1h 45m
2026-05-21 GPX3XJ - May 21, 11:25 UTCMay 21, 13:25 UTC2h 0m
2026-05-21 GPX3JX - May 21, 07:30 UTCMay 21, 09:50 UTC2h 20m
2026-05-20 GPX601 ZRH → PRN May 20, 18:35 UTCMay 20, 20:05 UTC1h 30m
2026-05-20 GPX600 PRN → ZRH May 20, 15:40 UTCMay 20, 17:25 UTC1h 45m
2026-05-20 GPX701 GVA → PRN May 20, 12:20 UTCMay 20, 13:55 UTC1h 35m
2026-05-20 GPX700 PRN → GVA May 20, 09:05 UTCMay 20, 11:05 UTC2h 0m
2026-05-19 GPX601 ZRH → PRN May 19, 18:45 UTCMay 19, 20:10 UTC1h 25m
2026-05-19 GPX600 PRN → ZRH May 19, 15:35 UTCMay 19, 17:20 UTC1h 45m
2026-05-18 GPX601 ZRH → PRN May 18, 18:45 UTCMay 18, 20:15 UTC1h 30m
2026-05-18 GPX600 PRN → ZRH May 18, 15:40 UTCMay 18, 17:25 UTC1h 45m
2026-05-17 GPX601 ZRH → PRN May 17, 18:30 UTCMay 17, 20:05 UTC1h 35m
2026-05-17 GPX600 PRN → ZRH May 17, 15:31 UTCMay 17, 17:10 UTC1h 40m
2026-05-17 GPX701 GVA → PRN May 17, 12:05 UTCMay 17, 13:45 UTC1h 40m
2026-05-17 GPX700 PRN → GVA May 17, 08:55 UTCMay 17, 10:50 UTC1h 55m
2026-05-17 GPX603 ZRH → PRN May 17, 06:10 UTCMay 17, 07:35 UTC1h 25m
2026-05-17 GPX602 PRN → ZRH May 17, 03:10 UTCMay 17, 04:50 UTC1h 40m
2026-05-16 GPX603 ZRH → PRN May 16, 19:05 UTCMay 16, 20:30 UTC1h 25m

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 LZ-GPA page for operator, model, and routing details .

Mode-S 4520FB frequently asked

What is Mode-S code 4520FB?
4520FB is an ICAO 24-bit transponder address. Allocated to Bulgaria. Assigned to LZ-GPA.
Where is Mode-S 4520FB registered?
Mode-S code 4520FB is allocated to Bulgaria (BG). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4520FB broadcasting right now?
No active broadcast right now. Last signal was 6h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4520FB, octal 21220373, decimal 4,530,427.
What flights does 4520FB operate?
Mode-S 4520FB has broadcast 16 distinct callsigns, including GPX601, GPX600, GPX701, GPX700, GPX2MI.