Apparatus

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sensors Mode-S transponder

8991AF

ICAO 24-bit transponder address · allocated to Taiwan

Hex
8991AF
Octal
42310657
Decimal
9,015,727
Country
TW
No current signal · last broadcast 27d ago
Flights observed
72
Distinct callsigns
20
Country
TW
Last broadcast
27d ago

Last known position

Most recent position reported by Mode-S 8991AF.

Country allocation

The ICAO 24-bit address 8991AF falls within the block assigned to Taiwan (TW) by ICAO Annex 10, Volume III. Every aircraft registered in Taiwan 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
CAL179 China Airlines 6 2026-07-25
CAL190 China Airlines 4 2026-07-24
CAL178 China Airlines 4 2026-07-25
CAL916 China Airlines 3 2026-07-19
CAL915 China Airlines 3 2026-07-19
CAL909 China Airlines 3 2026-07-20
CAL602 China Airlines 3 2026-07-24
CAL601 China Airlines 3 2026-07-23
CAL191 China Airlines 3 2026-07-25
CAL150 China Airlines 3 2026-07-20
CAL910 China Airlines 2 2026-07-20
CAL2528 - 2 2026-07-12
CAL195 China Airlines 2 2026-07-21
CAL189 - 2 2026-07-18
CAL188 China Airlines 2 2026-07-18
CAL1730 - 2 2026-06-27
CAL154 China Airlines 2 2026-07-26
CAL151 China Airlines 2 2026-07-21
CAL129 - 2 2026-07-18
CAL128 - 2 2026-07-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 CAL517 TPE → PEK Jul 26, 07:55 UTCJul 26, 15:35 UTC7h 40m
2026-07-26 CAL155 NGO → TPE Jul 26, 03:35 UTCJul 26, 05:55 UTC2h 20m
2026-07-26 CAL154 TPE → NGO Jul 26, 01:20 UTCJul 26, 02:00 UTC40m
2026-07-25 CAL154 TPE → NGO Jul 25, 23:45 UTCJul 26, 00:00 UTC15m
2026-07-25 CAL179 TAK → TPE Jul 25, 12:15 UTCJul 25, 12:35 UTC20m
2026-07-25 CAL179 TAK → TPE Jul 25, 10:20 UTCJul 25, 11:05 UTC45m
2026-07-25 CAL178 TPE → TAK Jul 25, 06:40 UTCJul 25, 08:55 UTC2h 15m
2026-07-25 CAL191 PUS → TPE Jul 25, 03:05 UTCJul 25, 03:25 UTC20m
2026-07-25 CAL191 PUS → TPE Jul 25, 01:30 UTCJul 25, 02:00 UTC30m
2026-07-24 CAL190 TPE → PUS Jul 24, 23:55 UTCJul 25, 00:15 UTC20m
2026-07-24 CAL190 TPE → PUS Jul 24, 22:25 UTCJul 24, 22:50 UTC25m
2026-07-24 CAL602 HKG → TPE Jul 24, 02:25 UTCJul 24, 03:45 UTC1h 20m
2026-07-23 CAL601 TPE → HKG Jul 23, 23:35 UTCJul 24, 01:00 UTC1h 25m
2026-07-23 CAL179 TAK → TPE Jul 23, 12:35 UTCJul 23, 13:00 UTC25m
2026-07-23 CAL179 TAK → TPE Jul 23, 10:45 UTCJul 23, 11:20 UTC35m
2026-07-23 CAL178 TPE → TAK Jul 23, 07:15 UTCJul 23, 09:30 UTC2h 15m
2026-07-23 CAL119 KOJ → TPE Jul 23, 05:15 UTCJul 23, 05:45 UTC30m
2026-07-23 CAL118 TPE → KOJ Jul 23, 00:45 UTCJul 23, 01:05 UTC20m
2026-07-22 CAL130 TPE → CTS Jul 22, 01:15 UTCJul 22, 04:45 UTC3h 30m
2026-07-21 CAL195 KMJ → TPE Jul 21, 11:40 UTCJul 21, 11:55 UTC15m
2026-07-21 CAL195 KMJ → TPE Jul 21, 10:05 UTCJul 21, 10:25 UTC20m
2026-07-21 CAL194 TPE → KMJ Jul 21, 06:55 UTCJul 21, 07:45 UTC50m
2026-07-21 CAL151 NGO → TPE Jul 21, 01:25 UTCJul 21, 03:40 UTC2h 15m
2026-07-20 CAL150 TPE → NGO Jul 20, 09:35 UTCJul 20, 11:55 UTC2h 20m
2026-07-20 CAL910 HKG → TPE Jul 20, 06:40 UTCJul 20, 08:05 UTC1h 25m
2026-07-20 CAL909 TPE → HKG Jul 20, 04:45 UTCJul 20, 05:05 UTC20m
2026-07-20 CAL909 TPE → HKG Jul 20, 03:35 UTCJul 20, 04:15 UTC40m
2026-07-19 CAL916 HKG → TPE Jul 19, 09:40 UTCJul 19, 11:10 UTC1h 30m
2026-07-19 CAL915 TPE → HKG Jul 19, 06:50 UTCJul 19, 08:05 UTC1h 15m
2026-07-19 CAL191 PUS → TPE Jul 19, 01:40 UTCJul 19, 03:40 UTC2h 0m
2026-07-19 CAL190 TPE → PUS Jul 19, 00:00 UTCJul 19, 00:15 UTC15m
2026-07-18 CAL190 TPE → PUS Jul 18, 22:25 UTCJul 18, 22:50 UTC25m
2026-07-18 CAL129 - Jul 18, 12:05 UTCJul 18, 12:25 UTC20m
2026-07-18 CAL129 - Jul 18, 10:40 UTCJul 18, 11:00 UTC20m
2026-07-18 CAL128 - Jul 18, 08:50 UTCJul 18, 09:05 UTC15m
2026-07-18 CAL128 - Jul 18, 07:25 UTCJul 18, 07:55 UTC30m
2026-07-18 CAL189 - Jul 18, 05:20 UTCJul 18, 05:40 UTC20m
2026-07-18 CAL189 - Jul 18, 03:50 UTCJul 18, 04:15 UTC25m
2026-07-18 CAL188 TPE → PUS Jul 18, 01:39 UTCJul 18, 02:00 UTC20m
2026-07-18 CAL188 TPE → PUS Jul 18, 00:10 UTCJul 18, 00:35 UTC25m
2026-07-17 CAL916 HKG → TPE Jul 17, 10:05 UTCJul 17, 11:39 UTC1h 35m
2026-07-17 CAL915 TPE → HKG Jul 17, 06:54 UTCJul 17, 08:20 UTC1h 25m
2026-07-17 CAL602 HKG → TPE Jul 17, 02:59 UTCJul 17, 04:44 UTC1h 45m
2026-07-16 CAL601 TPE → HKG Jul 16, 23:40 UTCJul 17, 01:05 UTC1h 25m
2026-07-16 CAL179 - Jul 16, 12:20 UTCJul 16, 12:44 UTC25m
2026-07-16 CAL179 - Jul 16, 10:25 UTCJul 16, 11:10 UTC45m
2026-07-16 CAL178 - Jul 16, 08:35 UTCJul 16, 09:15 UTC40m
2026-07-16 CAL178 - Jul 16, 07:05 UTCJul 16, 07:15 UTC10m
2026-07-16 CAL151 - Jul 16, 01:10 UTCJul 16, 03:45 UTC2h 35m
2026-07-15 CAL150 - Jul 15, 11:00 UTCJul 15, 11:45 UTC45m

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 8991AF frequently asked

What is Mode-S code 8991AF?
8991AF is an ICAO 24-bit transponder address. Allocated to Taiwan.
Where is Mode-S 8991AF registered?
Mode-S code 8991AF is allocated to Taiwan (TW). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 8991AF broadcasting right now?
No active broadcast right now. Last signal was 27d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 8991AF, octal 42310657, decimal 9,015,727.
What flights does 8991AF operate?
Mode-S 8991AF has broadcast 20 distinct callsigns, including CAL179, CAL190, CAL178, CAL916, CAL915.