Apparatus

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sensors Mode-S transponder

8991AB

ICAO 24-bit transponder address · allocated to Taiwan

Currently assigned to B-18359 · AIRBUS A-330-300

Hex
8991AB
Octal
42310653
Decimal
9,015,723
Country
TW
Tail
B-18359
Type
A333
No current signal · last broadcast 7h ago
Flights observed
346
Distinct callsigns
20
Country
TW
Last broadcast
7h ago

Last known position

Most recent position reported by Mode-S 8991AB.

Country allocation

The ICAO 24-bit address 8991AB 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
CAL221 - 53 2026-07-14
CAL223 - 45 2026-07-13
CAL220 - 34 2026-07-14
CAL222 - 32 2026-07-14
CAL201 - 17 2026-07-13
CAL111 - 12 2026-06-20
CAL110 China Airlines 10 2026-06-20
CAL173 China Airlines 9 2026-05-07
CAL919 - 8 2026-06-21
CAL834 China Airlines 8 2026-05-12
CAL202 - 8 2026-07-13
CAL703 - 7 2026-06-20
CAL704 - 6 2026-06-20
CAL702 - 6 2026-06-18
CAL701 China Airlines 6 2026-06-18
CAL172 China Airlines 6 2026-05-07
CAL833 China Airlines 5 2026-05-07
CAL157 - 5 2026-06-22
CAL153 China Airlines 5 2026-05-01
CAL131 China Airlines 5 2026-04-30

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 CAL222 TSA → HND Jul 14, 10:20 UTCJul 14, 13:20 UTC3h 0m
2026-07-14 CAL221 - Jul 14, 08:10 UTCJul 14, 08:40 UTC30m
2026-07-14 CAL221 - Jul 14, 05:55 UTCJul 14, 07:15 UTC1h 20m
2026-07-14 CAL220 TSA → HND Jul 14, 01:15 UTCJul 14, 04:05 UTC2h 50m
2026-07-13 CAL202 - Jul 13, 09:10 UTCJul 13, 10:00 UTC50m
2026-07-13 CAL201 - Jul 13, 04:30 UTCJul 13, 05:25 UTC55m
2026-07-13 CAL223 - Jul 13, 01:30 UTCJul 13, 02:01 UTC30m
2026-07-12 CAL223 - Jul 12, 23:15 UTCJul 13, 00:25 UTC1h 10m
2026-07-12 CAL222 TSA → HND Jul 12, 10:10 UTCJul 12, 13:10 UTC3h 0m
2026-07-12 CAL221 - Jul 12, 08:10 UTCJul 12, 08:30 UTC20m
2026-07-12 CAL221 - Jul 12, 05:40 UTCJul 12, 06:55 UTC1h 15m
2026-07-10 CAL222 - Jul 10, 10:10 UTCJul 10, 11:25 UTC1h 15m
2026-07-10 CAL222 - Jul 10, 08:45 UTCJul 10, 09:00 UTC15m
2026-07-10 CAL223 - Jul 10, 01:40 UTCJul 10, 02:00 UTC20m
2026-07-09 CAL223 - Jul 9, 23:05 UTCJul 10, 00:20 UTC1h 15m
2026-07-09 CAL222 - Jul 9, 11:00 UTCJul 9, 13:15 UTC2h 15m
2026-07-09 CAL222 - Jul 9, 10:20 UTCJul 9, 10:30 UTC10m
2026-07-09 CAL221 - Jul 9, 08:10 UTCJul 9, 08:25 UTC15m
2026-07-09 CAL221 - Jul 9, 05:40 UTCJul 9, 07:40 UTC2h 0m
2026-07-09 CAL220 TSA → HND Jul 9, 01:05 UTCJul 9, 04:00 UTC2h 55m
2026-07-08 CAL201 TSA → TSA Jul 8, 04:30 UTCJul 8, 10:00 UTC5h 30m
2026-07-08 CAL223 HND → TSA Jul 8, 01:25 UTCJul 8, 01:55 UTC30m
2026-07-07 CAL223 HND → TSA Jul 7, 23:05 UTCJul 8, 00:15 UTC1h 10m
2026-07-07 CAL222 - Jul 7, 11:55 UTCJul 7, 13:10 UTC1h 15m
2026-07-07 CAL222 - Jul 7, 10:20 UTCJul 7, 10:35 UTC15m
2026-07-07 CAL221 - Jul 7, 08:15 UTCJul 7, 08:35 UTC20m
2026-07-07 CAL221 - Jul 7, 05:45 UTCJul 7, 06:55 UTC1h 10m
2026-07-07 CAL220 TSA → HND Jul 7, 01:00 UTCJul 7, 03:50 UTC2h 50m
2026-07-06 CAL201 TSA → TSA Jul 6, 04:30 UTCJul 6, 10:05 UTC5h 35m
2026-07-06 CAL223 HND → TSA Jul 6, 01:40 UTCJul 6, 02:20 UTC40m
2026-07-05 CAL223 HND → TSA Jul 5, 23:05 UTCJul 6, 00:15 UTC1h 10m
2026-07-05 CAL222 TSA → HND Jul 5, 10:40 UTCJul 5, 13:20 UTC2h 40m
2026-07-05 CAL221 HND → TSA Jul 5, 06:05 UTCJul 5, 09:05 UTC3h 0m
2026-07-05 CAL220 TSA → HND Jul 5, 01:00 UTCJul 5, 03:45 UTC2h 45m
2026-07-04 CAL202 - Jul 4, 09:50 UTCJul 4, 10:10 UTC20m
2026-07-04 CAL201 - Jul 4, 04:30 UTCJul 4, 04:55 UTC25m
2026-07-04 CAL223 HND → TSA Jul 4, 01:45 UTCJul 4, 02:10 UTC25m
2026-07-03 CAL223 HND → TSA Jul 3, 23:05 UTCJul 4, 00:20 UTC1h 15m
2026-07-03 CAL222 TSA → HND Jul 3, 10:30 UTCJul 3, 13:20 UTC2h 50m
2026-07-03 CAL221 - Jul 3, 08:25 UTCJul 3, 09:05 UTC40m
2026-07-03 CAL221 - Jul 3, 05:45 UTCJul 3, 07:00 UTC1h 15m
2026-07-03 CAL220 TSA → HND Jul 3, 01:10 UTCJul 3, 03:50 UTC2h 40m
2026-07-02 CAL201 TSA → TSA Jul 2, 04:40 UTCJul 2, 10:05 UTC5h 25m
2026-07-02 CAL223 HND → TSA Jul 2, 01:30 UTCJul 2, 02:00 UTC30m
2026-07-01 CAL223 HND → TSA Jul 1, 23:10 UTCJul 2, 00:15 UTC1h 5m
2026-07-01 CAL222 TSA → HND Jul 1, 10:25 UTCJul 1, 13:15 UTC2h 50m
2026-07-01 CAL221 - Jul 1, 08:15 UTCJul 1, 08:45 UTC30m
2026-07-01 CAL221 - Jul 1, 05:45 UTCJul 1, 06:30 UTC45m
2026-07-01 CAL220 TSA → HND Jul 1, 01:10 UTCJul 1, 03:55 UTC2h 45m
2026-06-30 CAL202 - Jun 30, 09:35 UTCJun 30, 10:05 UTC30m

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 B-18359 page for operator, model, and routing details .

Mode-S 8991AB frequently asked

What is Mode-S code 8991AB?
8991AB is an ICAO 24-bit transponder address. Allocated to Taiwan. Assigned to B-18359.
Where is Mode-S 8991AB registered?
Mode-S code 8991AB is allocated to Taiwan (TW). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 8991AB broadcasting right now?
No active broadcast right now. Last signal was 7h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 8991AB, octal 42310653, decimal 9,015,723.
What flights does 8991AB operate?
Mode-S 8991AB has broadcast 20 distinct callsigns, including CAL221, CAL223, CAL220, CAL222, CAL201.