Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

4C0177

ICAO 24-bit transponder address · allocated to Serbia

Currently assigned to YU-ALX · ATR-72-600

Hex
4C0177
Octal
23000567
Decimal
4,981,111
Country
RS
Tail
YU-ALX
Type
AT76
No current signal · last broadcast 5h ago
Flights observed
364
Distinct callsigns
20
Country
RS
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S 4C0177.

Country allocation

The ICAO 24-bit address 4C0177 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 20 distinct

Callsign Airline Flights Last seen
ASL2429 Spurling Aviation 11 2026-06-20
ASL18R - 11 2026-06-19
ASL78V Spurling Aviation 10 2026-06-20
ASL78U - 10 2026-06-19
ASL2428 Spurling Aviation 10 2026-06-20
ASL36C - 9 2026-06-20
ASL26X Spurling Aviation 9 2026-06-21
ASL47P Spurling Aviation 8 2026-06-21
ASL72L Spurling Aviation 7 2026-06-12
ASL57F Spurling Aviation 7 2026-06-03
ASL51D Spurling Aviation 7 2026-07-13
ASL30J - 7 2026-07-13
ASL15A Spurling Aviation 7 2026-06-03
ASL10N Spurling Aviation 7 2026-06-12
ASL81C Spurling Aviation 6 2026-06-07
ASL77L - 6 2026-06-15
ASL49H Spurling Aviation 6 2026-06-07
ASL31Q - 6 2026-06-15
ASL31J Spurling Aviation 6 2026-06-17
ASL97E Spurling Aviation 5 2026-05-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 ASL37Z - Jul 13, 19:45 UTCJul 13, 20:45 UTC1h 0m
2026-07-13 ASL45T BEG → VIE Jul 13, 17:40 UTCJul 13, 18:55 UTC1h 15m
2026-07-13 ASL51D ZAG → BEG Jul 13, 15:20 UTCJul 13, 16:15 UTC55m
2026-07-13 ASL30J - Jul 13, 13:05 UTCJul 13, 13:55 UTC50m
2026-06-21 ASL159 KRK → BEG Jun 21, 19:09 UTCJun 21, 20:29 UTC1h 20m
2026-06-21 ASL158 BEG → KRK Jun 21, 16:44 UTCJun 21, 18:14 UTC1h 30m
2026-06-21 ASL47P SOF → BEG Jun 21, 13:39 UTCJun 21, 14:50 UTC1h 10m
2026-06-21 ASL26X BEG → SOF Jun 21, 11:30 UTCJun 21, 12:19 UTC50m
2026-06-21 ASL59L BRI → BEG Jun 21, 07:45 UTCJun 21, 09:10 UTC1h 25m
2026-06-21 ASL83D - Jun 21, 05:30 UTCJun 21, 06:40 UTC1h 10m
2026-06-20 ASL36C - Jun 20, 17:59 UTCJun 20, 18:24 UTC25m
2026-06-20 ASL31A BEG → LJU Jun 20, 16:24 UTCJun 20, 17:19 UTC55m
2026-06-20 ASL2429 IST → KVO Jun 20, 11:40 UTCJun 20, 13:09 UTC1h 30m
2026-06-20 ASL2428 KVO → IST Jun 20, 08:44 UTCJun 20, 10:29 UTC1h 45m
2026-06-20 ASL78V FCO → BEG Jun 20, 07:09 UTCJun 20, 07:29 UTC20m
2026-06-20 ASL12E SKG → BEG Jun 20, 01:29 UTCJun 20, 02:49 UTC1h 20m
2026-06-19 ASL24B BEG → SKG Jun 19, 22:55 UTCJun 20, 00:04 UTC1h 10m
2026-06-19 ASL80M BRI → BEG Jun 19, 18:44 UTCJun 19, 19:54 UTC1h 10m
2026-06-19 ASL24C BEG → BRI Jun 19, 16:25 UTCJun 19, 17:44 UTC1h 20m
2026-06-19 ASL47P SOF → BEG Jun 19, 13:09 UTCJun 19, 14:15 UTC1h 5m
2026-06-19 ASL26X BEG → SOF Jun 19, 11:20 UTCJun 19, 12:14 UTC55m
2026-06-19 ASL78U PRG → BEG Jun 19, 07:39 UTCJun 19, 09:19 UTC1h 40m
2026-06-19 ASL18R BEG → PRG Jun 19, 04:34 UTCJun 19, 06:29 UTC1h 55m
2026-06-18 ASL51D ZAG → BEG Jun 18, 13:15 UTCJun 18, 14:10 UTC55m
2026-06-18 ASL30J BEG → ZAG Jun 18, 11:30 UTCJun 18, 12:20 UTC50m
2026-06-18 ASL77W VCE → BEG Jun 18, 07:20 UTCJun 18, 08:55 UTC1h 35m
2026-06-18 ASL36Q BEG → VCE Jun 18, 04:45 UTCJun 18, 06:25 UTC1h 40m
2026-06-18 ASL12E SKG → BEG Jun 18, 01:35 UTCJun 18, 02:55 UTC1h 20m
2026-06-17 ASL24B BEG → SKG Jun 17, 22:50 UTCJun 17, 23:55 UTC1h 5m
2026-06-17 ASL18W ZAG → BEG Jun 17, 18:40 UTCJun 17, 19:25 UTC45m
2026-06-17 ASL31J BEG → ZAG Jun 17, 17:00 UTCJun 17, 17:50 UTC50m
2026-06-17 ASL47P SOF → BEG Jun 17, 13:15 UTCJun 17, 14:20 UTC1h 5m
2026-06-17 ASL26X BEG → SOF Jun 17, 11:15 UTCJun 17, 12:00 UTC45m
2026-06-16 ASL36C - Jun 16, 18:05 UTCJun 16, 18:25 UTC20m
2026-06-16 ASL31A BEG → LJU Jun 16, 16:25 UTCJun 16, 17:19 UTC55m
2026-06-16 ASL77A BEG → HAJ Jun 16, 14:39 UTCJun 16, 15:30 UTC50m
2026-06-16 ASL2429 IST → KVO Jun 16, 11:45 UTCJun 16, 13:09 UTC1h 25m
2026-06-16 ASL2428 KVO → IST Jun 16, 08:39 UTCJun 16, 10:09 UTC1h 30m
2026-06-16 ASL78V FCO → BEG Jun 16, 07:09 UTCJun 16, 07:40 UTC30m
2026-06-15 ASL70V SZG → BEG Jun 15, 20:15 UTCJun 15, 21:35 UTC1h 20m
2026-06-15 ASL21W BEG → SZG Jun 15, 17:45 UTCJun 15, 19:30 UTC1h 45m
2026-06-15 ASL61J BEG → TIV Jun 15, 13:00 UTCJun 15, 14:05 UTC1h 5m
2026-06-15 ASL77B BEG → VIE Jun 15, 10:55 UTCJun 15, 12:05 UTC1h 10m
2026-06-15 ASL31Q - Jun 15, 07:45 UTCJun 15, 08:45 UTC1h 0m
2026-06-15 ASL77L - Jun 15, 05:35 UTCJun 15, 06:55 UTC1h 20m
2026-06-14 ASL18W ZAG → BEG Jun 14, 22:10 UTCJun 14, 22:55 UTC45m
2026-06-14 ASL31J BEG → ZAG Jun 14, 20:15 UTCJun 14, 21:15 UTC1h 0m
2026-06-14 ASL59E BUD → BEG Jun 14, 17:30 UTCJun 14, 18:30 UTC1h 0m
2026-06-14 ASL57U BEG → BUD Jun 14, 15:45 UTCJun 14, 16:45 UTC1h 0m
2026-06-14 ASL51D ZAG → BEG Jun 14, 13:25 UTCJun 14, 14:15 UTC50m

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-ALX page for operator, model, and routing details .

Mode-S 4C0177 frequently asked

What is Mode-S code 4C0177?
4C0177 is an ICAO 24-bit transponder address. Allocated to Serbia. Assigned to YU-ALX.
Where is Mode-S 4C0177 registered?
Mode-S code 4C0177 is allocated to Serbia (RS). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4C0177 broadcasting right now?
No active broadcast right now. Last signal was 5h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4C0177, octal 23000567, decimal 4,981,111.
What flights does 4C0177 operate?
Mode-S 4C0177 has broadcast 20 distinct callsigns, including ASL2429, ASL18R, ASL78V, ASL78U, ASL2428.