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 Jul 26, 20:30 UTC
Flights observed
409
Distinct callsigns
20
Country
BG
Last broadcast
Jul 26, 20:30 UTC

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 20 distinct

Callsign Airline Flights Last seen
GPX601 GP Aviation 60 2026-07-23
GPX600 GP Aviation 60 2026-07-23
GPX701 GP Aviation 46 2026-07-24
GPX700 GP Aviation 45 2026-07-25
GPX2MI GP Aviation 32 2026-07-26
GPX2IM GP Aviation 31 2026-07-26
GPX602 - 18 2026-07-11
GPX603 - 17 2026-07-11
GPX1LB GP Aviation 16 2026-07-22
GPX1BL GP Aviation 16 2026-07-22
GPX3XJ - 11 2026-07-21
GPX3JX - 11 2026-07-21
GPX802 - 5 2026-07-04
GPX4961 GP Aviation 5 2026-07-02
GPX4960 GP Aviation 5 2026-07-02
GPX803 - 4 2026-07-04
GPX7JE - 3 2026-06-24
GPX7EJ - 3 2026-06-24
GPX702 - 2 2026-07-25
GPX605 GP Aviation 2 2026-07-19

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 GPX2IM BSL → PRN Jul 26, 19:15 UTCJul 26, 20:30 UTC1h 15m
2026-07-26 GPX2MI PRN → BSL Jul 26, 12:45 UTCJul 26, 17:35 UTC4h 50m
2026-07-25 GPX700 PRN → GVA Jul 25, 18:25 UTCJul 26, 11:10 UTC16h 46m
2026-07-25 GPX702 ZRH → GVA Jul 25, 12:30 UTCJul 25, 17:15 UTC4h 45m
2026-07-24 GPX2IM BSL → PRN Jul 24, 18:35 UTCJul 25, 11:25 UTC16h 50m
2026-07-24 GPX2MI PRN → BSL Jul 24, 15:35 UTCJul 24, 17:20 UTC1h 45m
2026-07-24 GPX701 GVA → PRN Jul 24, 12:30 UTCJul 24, 14:10 UTC1h 40m
2026-07-24 GPX700 PRN → GVA Jul 24, 09:10 UTCJul 24, 11:10 UTC2h 0m
2026-07-23 GPX601 ZRH → PRN Jul 23, 19:05 UTCJul 23, 20:35 UTC1h 30m
2026-07-23 GPX600 PRN → ZRH Jul 23, 16:00 UTCJul 23, 17:45 UTC1h 45m
2026-07-23 GPX701 GVA → PRN Jul 23, 12:15 UTCJul 23, 13:40 UTC1h 25m
2026-07-23 GPX700 PRN → GVA Jul 23, 09:05 UTCJul 23, 11:05 UTC2h 0m
2026-07-22 GPX601 ZRH → PRN Jul 22, 19:25 UTCJul 22, 20:55 UTC1h 30m
2026-07-22 GPX600 PRN → ZRH Jul 22, 16:25 UTCJul 22, 18:20 UTC1h 55m
2026-07-22 GPX1LB BSL → PRN Jul 22, 13:20 UTCJul 22, 14:50 UTC1h 30m
2026-07-22 GPX1BL PRN → BSL Jul 22, 10:20 UTCJul 22, 12:25 UTC2h 5m
2026-07-21 GPX2IM BSL → PRN Jul 21, 19:15 UTCJul 21, 20:50 UTC1h 35m
2026-07-21 GPX2MI PRN → BSL Jul 21, 16:20 UTCJul 21, 18:25 UTC2h 5m
2026-07-21 GPX3XJ - Jul 21, 10:00 UTCJul 21, 12:10 UTC2h 10m
2026-07-21 GPX3JX - Jul 21, 06:20 UTCJul 21, 08:35 UTC2h 15m
2026-07-20 GPX601 ZRH → PRN Jul 20, 19:05 UTCJul 20, 20:40 UTC1h 35m
2026-07-20 GPX600 PRN → ZRH Jul 20, 15:40 UTCJul 20, 17:50 UTC2h 10m
2026-07-20 GPX701 GVA → PRN Jul 20, 12:10 UTCJul 20, 13:45 UTC1h 35m
2026-07-20 GPX700 PRN → GVA Jul 20, 09:05 UTCJul 20, 11:00 UTC1h 55m
2026-07-19 GPX2IM - Jul 19, 18:30 UTCJul 19, 20:05 UTC1h 35m
2026-07-19 GPX2MI PRN → BSL Jul 19, 15:30 UTCJul 19, 17:25 UTC1h 55m
2026-07-19 GPX701 GVA → PRN Jul 19, 12:05 UTCJul 19, 13:30 UTC1h 25m
2026-07-19 GPX700 PRN → GVA Jul 19, 09:10 UTCJul 19, 11:05 UTC1h 55m
2026-07-19 GPX605 ZRH → PRN Jul 19, 06:25 UTCJul 19, 07:45 UTC1h 20m
2026-07-19 GPX604 PRN → ZRH Jul 19, 02:55 UTCJul 19, 04:45 UTC1h 50m
2026-07-18 GPX703 - Jul 18, 18:45 UTCJul 18, 20:30 UTC1h 45m
2026-07-18 GPX702 - Jul 18, 15:35 UTCJul 18, 17:50 UTC2h 15m
2026-07-18 GPX601 - Jul 18, 12:50 UTCJul 18, 14:20 UTC1h 30m
2026-07-18 GPX600 - Jul 18, 09:30 UTCJul 18, 11:25 UTC1h 55m
2026-07-17 GPX807 BSL → PRN Jul 17, 19:55 UTCJul 17, 21:25 UTC1h 30m
2026-07-17 GPX806 PRN → BSL Jul 17, 16:44 UTCJul 17, 18:44 UTC2h 0m
2026-07-17 GPX1LB - Jul 17, 13:50 UTCJul 17, 15:15 UTC1h 25m
2026-07-17 GPX1BL - Jul 17, 10:20 UTCJul 17, 12:25 UTC2h 5m
2026-07-16 GPX601 - Jul 16, 18:44 UTCJul 16, 20:09 UTC1h 25m
2026-07-16 GPX600 - Jul 16, 15:45 UTCJul 16, 17:30 UTC1h 45m
2026-07-16 GPX701 - Jul 16, 12:09 UTCJul 16, 13:54 UTC1h 45m
2026-07-16 GPX700 - Jul 16, 09:00 UTCJul 16, 10:59 UTC2h 0m
2026-07-15 GPX601 - Jul 15, 19:45 UTCJul 15, 21:10 UTC1h 25m
2026-07-15 GPX600 - Jul 15, 16:25 UTCJul 15, 18:25 UTC2h 0m
2026-07-15 GPX1LB - Jul 15, 13:15 UTCJul 15, 14:55 UTC1h 40m
2026-07-15 GPX1BL - Jul 15, 10:05 UTCJul 15, 12:05 UTC2h 0m
2026-07-14 GPX2IM - Jul 14, 18:30 UTCJul 14, 20:05 UTC1h 35m
2026-07-14 GPX2MI - Jul 14, 15:25 UTCJul 14, 17:15 UTC1h 50m
2026-07-14 GPX3XJ - Jul 14, 10:10 UTCJul 14, 12:05 UTC1h 55m
2026-07-14 GPX3JX - Jul 14, 06:20 UTCJul 14, 08:35 UTC2h 15m

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 Jul 26, 20:30 UTC.
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 20 distinct callsigns, including GPX601, GPX600, GPX701, GPX700, GPX2MI.