Apparatus

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sensors Mode-S transponder

8991B4

ICAO 24-bit transponder address · allocated to Taiwan

Currently assigned to B-18306 · AIRBUS A-330-300

Hex
8991B4
Octal
42310664
Decimal
9,015,732
Country
TW
Tail
B-18306
Type
A333
No current signal · last broadcast Jul 26, 13:50 UTC
Flights observed
355
Distinct callsigns
20
Country
TW
Last broadcast
Jul 26, 13:50 UTC

Last known position

Most recent position reported by Mode-S 8991B4.

Country allocation

The ICAO 24-bit address 8991B4 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
CAL117 China Airlines 28 2026-07-25
CAL116 China Airlines 21 2026-07-25
CAL157 China Airlines 15 2026-07-21
CAL791 - 14 2026-07-02
CAL792 - 13 2026-07-02
CAL836 - 12 2026-07-17
CAL835 - 12 2026-07-17
CAL131 - 12 2026-07-06
CAL156 China Airlines 10 2026-07-21
CAL121 China Airlines 10 2026-07-22
CAL163 China Airlines 9 2026-07-26
CAL162 China Airlines 9 2026-07-26
CAL130 - 9 2026-07-06
CAL702 China Airlines 8 2026-06-11
CAL701 China Airlines 8 2026-06-11
CAL521 - 8 2026-07-14
CAL120 China Airlines 8 2026-07-22
CAL111 - 8 2026-07-03
CAL522 - 7 2026-07-14
CAL161 China Airlines 7 2026-07-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 CAL163 ICN → TPE Jul 26, 11:45 UTCJul 26, 13:50 UTC2h 5m
2026-07-26 CAL162 TPE → ICN Jul 26, 07:55 UTCJul 26, 10:05 UTC2h 10m
2026-07-26 CAL161 ICN → TPE Jul 26, 05:40 UTCJul 26, 06:05 UTC25m
2026-07-26 CAL161 ICN → TPE Jul 26, 04:05 UTCJul 26, 04:45 UTC40m
2026-07-26 CAL160 TPE → ICN Jul 26, 00:10 UTCJul 26, 02:15 UTC2h 5m
2026-07-25 CAL117 FUK → TPE Jul 25, 14:00 UTCJul 25, 14:15 UTC15m
2026-07-25 CAL117 FUK → TPE Jul 25, 12:35 UTCJul 25, 13:00 UTC25m
2026-07-25 CAL116 TPE → FUK Jul 25, 09:15 UTCJul 25, 11:00 UTC1h 45m
2026-07-25 CAL904 HKG → TPE Jul 25, 04:15 UTCJul 25, 05:50 UTC1h 35m
2026-07-25 CAL903 TPE → HKG Jul 25, 00:35 UTCJul 25, 01:55 UTC1h 20m
2026-07-24 CAL153 KIX → TPE Jul 24, 05:40 UTCJul 24, 08:10 UTC2h 30m
2026-07-24 CAL152 TPE → KIX Jul 24, 01:35 UTCJul 24, 03:55 UTC2h 20m
2026-07-23 CAL528 - Jul 23, 10:20 UTCJul 23, 11:35 UTC1h 15m
2026-07-23 CAL527 TPE → SZX Jul 23, 07:20 UTCJul 23, 08:30 UTC1h 10m
2026-07-23 MDA992 TPE → TPE Jul 23, 01:00 UTCJul 23, 05:30 UTC4h 30m
2026-07-22 CAL105 NRT → TPE Jul 22, 13:30 UTCJul 22, 13:50 UTC20m
2026-07-22 CAL105 NRT → TPE Jul 22, 11:10 UTCJul 22, 12:15 UTC1h 5m
2026-07-22 CAL121 OKA → TPE Jul 22, 04:10 UTCJul 22, 04:25 UTC15m
2026-07-22 CAL121 OKA → TPE Jul 22, 03:25 UTCJul 22, 03:35 UTC10m
2026-07-22 CAL120 TPE → OKA Jul 22, 00:50 UTCJul 22, 01:15 UTC25m
2026-07-21 CAL157 KIX → TPE Jul 21, 05:05 UTCJul 21, 07:30 UTC2h 25m
2026-07-21 CAL156 TPE → KIX Jul 21, 01:05 UTCJul 21, 03:20 UTC2h 15m
2026-07-20 CAL105 NRT → TPE Jul 20, 11:55 UTCJul 20, 12:20 UTC25m
2026-07-20 CAL105 NRT → TPE Jul 20, 09:25 UTCJul 20, 10:50 UTC1h 25m
2026-07-20 CAL104 TPE → NRT Jul 20, 04:40 UTCJul 20, 07:35 UTC2h 55m
2026-07-19 CAL832 - Jul 19, 09:05 UTCJul 19, 10:25 UTC1h 20m
2026-07-19 CAL832 - Jul 19, 06:40 UTCJul 19, 06:55 UTC15m
2026-07-19 CAL831 TPE → BKK Jul 19, 04:45 UTCJul 19, 04:55 UTC10m
2026-07-19 CAL831 TPE → BKK Jul 19, 01:50 UTCJul 19, 02:50 UTC1h 0m
2026-07-17 CAL836 - Jul 17, 11:10 UTCJul 17, 14:44 UTC3h 35m
2026-07-17 CAL835 - Jul 17, 08:49 UTCJul 17, 08:59 UTC10m
2026-07-17 CAL835 - Jul 17, 05:55 UTCJul 17, 06:54 UTC1h 0m
2026-07-15 CAL121 - Jul 15, 04:00 UTCJul 15, 04:10 UTC10m
2026-07-15 CAL120 - Jul 15, 01:30 UTCJul 15, 01:45 UTC15m
2026-07-15 CAL120 - Jul 15, 00:30 UTCJul 15, 00:45 UTC15m
2026-07-14 CAL522 - Jul 14, 10:15 UTCJul 14, 11:40 UTC1h 25m
2026-07-14 CAL521 - Jul 14, 06:30 UTCJul 14, 07:55 UTC1h 25m
2026-07-14 CAL121 - Jul 14, 04:00 UTCJul 14, 04:35 UTC35m
2026-07-14 CAL120 - Jul 14, 01:15 UTCJul 14, 01:25 UTC10m
2026-07-14 CAL120 - Jul 14, 00:15 UTCJul 14, 00:40 UTC25m
2026-07-13 CAL157 KIX → TPE Jul 13, 04:30 UTCJul 13, 06:45 UTC2h 15m
2026-07-13 CAL156 TPE → KIX Jul 13, 00:35 UTCJul 13, 02:55 UTC2h 20m
2026-07-12 CAL924 HKG → TPE Jul 12, 13:55 UTCJul 12, 15:25 UTC1h 30m
2026-07-12 CAL923 TPE → HKG Jul 12, 10:40 UTCJul 12, 11:55 UTC1h 15m
2026-07-12 CAL552 TPE → TPE Jul 12, 01:25 UTCJul 12, 08:55 UTC7h 30m
2026-07-09 CAL157 - Jul 9, 04:30 UTCJul 9, 06:55 UTC2h 25m
2026-07-09 CAL156 - Jul 9, 00:40 UTCJul 9, 02:55 UTC2h 15m
2026-07-08 CAL101 - Jul 8, 08:35 UTCJul 8, 09:00 UTC25m
2026-07-08 CAL101 - Jul 8, 06:10 UTCJul 8, 07:25 UTC1h 15m
2026-07-08 CAL100 - Jul 8, 03:00 UTCJul 8, 04:20 UTC1h 20m

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-18306 page for operator, model, and routing details .

Mode-S 8991B4 frequently asked

What is Mode-S code 8991B4?
8991B4 is an ICAO 24-bit transponder address. Allocated to Taiwan. Assigned to B-18306.
Where is Mode-S 8991B4 registered?
Mode-S code 8991B4 is allocated to Taiwan (TW). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 8991B4 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 13:50 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 8991B4, octal 42310664, decimal 9,015,732.
What flights does 8991B4 operate?
Mode-S 8991B4 has broadcast 20 distinct callsigns, including CAL117, CAL116, CAL157, CAL791, CAL792.