Apparatus

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sensors Mode-S transponder

8991A7

ICAO 24-bit transponder address · allocated to Taiwan

Currently assigned to B-18660 · BOEING 737-800

Hex
8991A7
Octal
42310647
Decimal
9,015,719
Country
TW
Tail
B-18660
Type
B738
Broadcasting now · callsign CAL167 · 34,000 ft
Flights observed
394
Distinct callsigns
20
Country
TW
Last broadcast
Jul 26, 13:05 UTC

Current position

8991A7 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address 8991A7 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
MDA797 - 25 2026-07-20
MDA798 - 24 2026-07-20
MDA355 - 24 2026-07-20
MDA356 - 23 2026-07-20
CAL132 China Airlines 21 2026-06-09
MDA1858 Mandarin Airlines 19 2026-07-26
CAL198 China Airlines 17 2026-06-09
CAL133 China Airlines 17 2026-06-05
MDA1857 Mandarin Airlines 16 2026-07-25
CAL167 China Airlines 16 2026-06-12
CAL139 China Airlines 16 2026-06-11
CAL199 China Airlines 14 2026-06-10
CAL166 China Airlines 13 2026-06-11
CAL583 China Airlines 11 2026-06-11
CAL138 China Airlines 11 2026-06-10
CAL915 - 9 2026-06-18
CAL923 - 8 2026-06-19
CAL840 China Airlines 7 2026-06-06
CAL839 China Airlines 7 2026-06-06
MDA770 Mandarin Airlines 5 2026-07-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 CAL7853 RMQ → TPE Jul 26, 12:30 UTCJul 26, 13:05 UTC35m
2026-07-26 MDA770 KNH → RMQ Jul 26, 11:10 UTCJul 26, 11:30 UTC20m
2026-07-26 MDA769 RMQ → KNH Jul 26, 09:00 UTCJul 26, 09:20 UTC20m
2026-07-26 MDA1858 SGN → RMQ Jul 26, 00:15 UTCJul 26, 07:50 UTC7h 36m
2026-07-25 MDA770 KNH → RMQ Jul 25, 10:55 UTCJul 25, 11:15 UTC20m
2026-07-25 MDA769 RMQ → KNH Jul 25, 09:10 UTCJul 25, 09:30 UTC20m
2026-07-25 MDA1858 SGN → RMQ Jul 25, 06:55 UTCJul 25, 07:50 UTC55m
2026-07-25 MDA1857 RMQ → SGN Jul 25, 00:20 UTCJul 25, 01:10 UTC50m
2026-07-24 MDA770 KNH → RMQ Jul 24, 11:15 UTCJul 24, 11:35 UTC20m
2026-07-24 MDA769 RMQ → KNH Jul 24, 09:10 UTCJul 24, 09:25 UTC15m
2026-07-24 MDA1858 SGN → RMQ Jul 24, 00:15 UTCJul 24, 07:25 UTC7h 10m
2026-07-23 MDA770 KNH → RMQ Jul 23, 11:20 UTCJul 23, 11:40 UTC20m
2026-07-23 MDA769 RMQ → KNH Jul 23, 09:30 UTCJul 23, 09:45 UTC15m
2026-07-23 MDA1857 RMQ → SGN Jul 23, 00:20 UTCJul 23, 07:50 UTC7h 30m
2026-07-22 MDA1857 RMQ → SGN Jul 22, 00:20 UTCJul 22, 01:10 UTC50m
2026-07-21 MDA770 KNH → RMQ Jul 21, 11:10 UTCJul 21, 11:30 UTC20m
2026-07-21 MDA769 RMQ → KNH Jul 21, 09:00 UTCJul 21, 09:15 UTC15m
2026-07-21 MDA1857 RMQ → SGN Jul 21, 00:15 UTCJul 21, 07:45 UTC7h 30m
2026-07-20 MDA798 - Jul 20, 13:55 UTCJul 20, 14:15 UTC20m
2026-07-20 MDA355 - Jul 20, 12:15 UTCJul 20, 12:40 UTC25m
2026-07-20 MDA356 - Jul 20, 10:55 UTCJul 20, 11:10 UTC15m
2026-07-20 MDA797 - Jul 20, 09:15 UTCJul 20, 09:35 UTC20m
2026-07-20 MDA1858 SGN → RMQ Jul 20, 00:15 UTCJul 20, 07:35 UTC7h 20m
2026-07-19 MDA798 - Jul 19, 13:55 UTCJul 19, 14:15 UTC20m
2026-07-19 MDA355 - Jul 19, 12:25 UTCJul 19, 12:50 UTC25m
2026-07-19 MDA356 MZG → KHH Jul 19, 11:00 UTCJul 19, 11:20 UTC20m
2026-07-19 MDA797 - Jul 19, 09:30 UTCJul 19, 09:45 UTC15m
2026-07-19 MDA1857 - Jul 19, 00:30 UTCJul 19, 07:55 UTC7h 25m
2026-07-18 MDA798 - Jul 18, 13:45 UTCJul 18, 14:05 UTC20m
2026-07-18 MDA355 - Jul 18, 12:15 UTCJul 18, 12:35 UTC20m
2026-07-18 MDA356 - Jul 18, 10:45 UTCJul 18, 11:05 UTC20m
2026-07-18 MDA797 - Jul 18, 09:05 UTCJul 18, 09:20 UTC15m
2026-07-18 MDA1857 - Jul 18, 00:10 UTCJul 18, 07:40 UTC7h 31m
2026-07-17 MDA798 - Jul 17, 13:55 UTCJul 17, 14:10 UTC15m
2026-07-17 MDA355 - Jul 17, 12:35 UTCJul 17, 13:00 UTC25m
2026-07-17 MDA356 - Jul 17, 11:04 UTCJul 17, 11:25 UTC20m
2026-07-17 MDA797 - Jul 17, 09:45 UTCJul 17, 10:00 UTC15m
2026-07-17 MDA1857 - Jul 17, 00:25 UTCJul 17, 07:50 UTC7h 25m
2026-07-16 MDA798 - Jul 16, 13:45 UTCJul 16, 14:00 UTC15m
2026-07-16 MDA355 - Jul 16, 12:09 UTCJul 16, 12:30 UTC20m
2026-07-16 MDA356 - Jul 16, 10:50 UTCJul 16, 11:05 UTC15m
2026-07-16 MDA797 - Jul 16, 09:10 UTCJul 16, 09:25 UTC15m
2026-07-16 MDA1858 - Jul 16, 00:15 UTCJul 16, 07:35 UTC7h 20m
2026-07-15 MDA798 - Jul 15, 13:50 UTCJul 15, 14:05 UTC15m
2026-07-15 MDA355 - Jul 15, 12:05 UTCJul 15, 12:30 UTC25m
2026-07-15 MDA356 MZG → KHH Jul 15, 10:40 UTCJul 15, 11:05 UTC25m
2026-07-15 MDA797 - Jul 15, 09:10 UTCJul 15, 09:30 UTC20m
2026-07-15 MDA1858 - Jul 15, 00:20 UTCJul 15, 07:40 UTC7h 20m
2026-07-14 MDA798 - Jul 14, 13:40 UTCJul 14, 13:55 UTC15m
2026-07-14 MDA355 - Jul 14, 12:15 UTCJul 14, 12:35 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.

Prefer a tail-number view? See the B-18660 page for operator, model, and routing details .

Mode-S 8991A7 frequently asked

What is Mode-S code 8991A7?
8991A7 is an ICAO 24-bit transponder address. Allocated to Taiwan. Assigned to B-18660.
Where is Mode-S 8991A7 registered?
Mode-S code 8991A7 is allocated to Taiwan (TW). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 8991A7 broadcasting right now?
Yes. Mode-S 8991A7 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 8991A7, octal 42310647, decimal 9,015,719.
What flights does 8991A7 operate?
Mode-S 8991A7 has broadcast 20 distinct callsigns, including MDA797, MDA798, MDA355, MDA356, CAL132.