Apparatus

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sensors Mode-S transponder

0AC9B9

ICAO 24-bit transponder address · allocated to Costa Rica

Hex
0AC9B9
Octal
02544671
Decimal
707,001
Country
CR
No current signal · last broadcast Jul 25, 14:10 UTC
Flights observed
27
Distinct callsigns
1
Country
CR
Last broadcast
Jul 25, 14:10 UTC

Last known position

Most recent position reported by Mode-S 0AC9B9.

Country allocation

The ICAO 24-bit address 0AC9B9 falls within the block assigned to Costa Rica (CR) by ICAO Annex 10, Volume III. Every aircraft registered in Costa Rica 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 1 distinct

Callsign Airline Flights Last seen
HK5238 - 27 2026-07-25

Recent flights last 27

DateFlightRouteTakeoffLandingDuration
2026-07-25 HK5238 - Jul 25, 14:00 UTCJul 25, 14:10 UTC10m
2026-07-24 HK5238 - Jul 24, 18:05 UTCJul 24, 18:45 UTC40m
2026-07-23 HK5238 - Jul 23, 19:20 UTCJul 23, 20:10 UTC50m
2026-07-23 HK5238 - Jul 23, 17:35 UTCJul 23, 17:45 UTC10m
2026-07-23 HK5238 - Jul 23, 11:25 UTCJul 23, 11:35 UTC10m
2026-07-22 HK5238 - Jul 22, 15:35 UTCJul 22, 15:45 UTC10m
2026-07-22 HK5238 - Jul 22, 12:55 UTCJul 22, 13:05 UTC10m
2026-07-21 HK5238 - Jul 21, 16:05 UTCJul 21, 16:10 UTC5m
2026-07-21 HK5238 - Jul 21, 11:00 UTCJul 21, 11:45 UTC45m
2026-07-19 HK5238 - Jul 19, 14:15 UTCJul 19, 14:25 UTC10m
2026-07-19 HK5238 - Jul 19, 12:30 UTCJul 19, 13:20 UTC50m
2026-07-18 HK5238 - Jul 18, 21:25 UTCJul 18, 22:10 UTC45m
2026-07-18 HK5238 - Jul 18, 20:20 UTCJul 18, 20:35 UTC15m
2026-07-18 HK5238 - Jul 18, 15:25 UTCJul 18, 16:15 UTC50m
2026-07-18 HK5238 - Jul 18, 11:40 UTCJul 18, 11:55 UTC15m
2026-07-17 HK5238 - Jul 17, 19:25 UTCJul 17, 20:25 UTC1h 0m
2026-07-16 HK5238 - Jul 16, 18:40 UTCJul 16, 18:50 UTC10m
2026-07-16 HK5238 - Jul 16, 15:35 UTCJul 16, 15:40 UTC5m
2026-07-16 HK5238 EOH → EOH Jul 16, 14:40 UTCJul 16, 14:50 UTC10m
2026-07-15 HK5238 - Jul 15, 22:45 UTCJul 15, 23:05 UTC20m
2026-07-15 HK5238 - Jul 15, 20:25 UTCJul 15, 21:15 UTC50m
2026-07-15 HK5238 - Jul 15, 17:50 UTCJul 15, 18:00 UTC10m
2026-07-15 HK5238 - Jul 15, 11:25 UTCJul 15, 11:45 UTC20m
2026-06-18 HK5238 - Jun 18, 20:00 UTCJun 18, 20:10 UTC10m
2026-06-18 HK5238 - Jun 18, 18:20 UTCJun 18, 18:30 UTC10m
2026-06-18 HK5238 - Jun 18, 14:25 UTCJun 18, 14:35 UTC10m
2026-06-09 HK5238 - Jun 9, 14:35 UTCJun 9, 14:55 UTC20m

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.

Mode-S 0AC9B9 frequently asked

What is Mode-S code 0AC9B9?
0AC9B9 is an ICAO 24-bit transponder address. Allocated to Costa Rica.
Where is Mode-S 0AC9B9 registered?
Mode-S code 0AC9B9 is allocated to Costa Rica (CR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 0AC9B9 broadcasting right now?
No active broadcast right now. Last signal was Jul 25, 14:10 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 0AC9B9, octal 02544671, decimal 707,001.
What flights does 0AC9B9 operate?
Mode-S 0AC9B9 has broadcast 1 distinct callsign, including HK5238.