Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A8B9B3

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N661UA · BOEING 767-300 · operated by UNITED AIRLINES INC

Hex
A8B9B3
Octal
52134663
Decimal
11,057,587
Country
US
Tail
N661UA
Type
B763
No current signal · last broadcast Jul 26, 22:45 UTC
Flights observed
252
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:45 UTC

Last known position

Most recent position reported by Mode-S A8B9B3.

Country allocation

The ICAO 24-bit address A8B9B3 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States 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
UAL135 - 13 2026-07-11
UAL904 - 12 2026-07-16
UAL55 United Airlines 12 2026-05-11
UAL134 - 11 2026-06-20
UAL3 - 10 2026-07-10
UAL958 - 9 2026-07-10
UAL941 United Airlines 9 2026-07-23
UAL940 United Airlines 9 2026-07-26
UAL54 United Airlines 9 2026-05-11
UAL147 - 9 2026-07-12
UAL964 United Airlines 8 2026-06-05
UAL957 United Airlines 8 2026-06-18
UAL921 - 8 2026-07-17
UAL306 United Airlines 8 2026-06-15
UAL965 United Airlines 7 2026-06-06
UAL934 - 7 2026-07-09
UAL920 United Airlines 7 2026-06-27
UAL959 United Airlines 6 2026-07-26
UAL956 - 6 2026-06-17
UAL17 - 6 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL929 ORD → LHR Jul 26, 21:55 UTCJul 26, 22:45 UTC50m
2026-07-26 UAL959 LHR → ORD Jul 26, 10:30 UTCJul 26, 18:37 UTC8h 7m
2026-07-26 UAL959 LHR → ORD Jul 26, 10:25 UTCJul 26, 10:45 UTC20m
2026-07-26 UAL940 EWR → LHR Jul 26, 01:41 UTCJul 26, 07:35 UTC5h 54m
2026-07-26 UAL940 EWR → LHR Jul 26, 01:20 UTCJul 26, 07:45 UTC6h 26m
2026-07-25 UAL967 NAP → EWR Jul 25, 19:55 UTCJul 25, 21:20 UTC1h 25m
2026-07-25 UAL967 NAP → EWR Jul 25, 12:35 UTCJul 25, 19:50 UTC7h 15m
2026-07-25 UAL966 EWR → NAP Jul 25, 01:15 UTCJul 25, 09:20 UTC8h 5m
2026-07-24 UAL967 NAP → EWR Jul 24, 12:40 UTCJul 24, 21:35 UTC8h 55m
2026-07-24 UAL967 NAP → EWR Jul 24, 12:24 UTCJul 24, 21:25 UTC9h 1m
2026-07-24 UAL966 EWR → NAP Jul 24, 01:20 UTCJul 24, 09:20 UTC8h 0m
2026-07-23 UAL941 LHR → EWR Jul 23, 15:35 UTCJul 23, 23:00 UTC7h 25m
2026-07-23 UAL941 LHR → EWR Jul 23, 15:24 UTCJul 23, 22:56 UTC7h 32m
2026-07-23 UAL146 EWR → LHR Jul 23, 03:10 UTCJul 23, 04:30 UTC1h 20m
2026-07-23 UAL146 EWR → LHR Jul 23, 02:49 UTCJul 23, 09:52 UTC7h 3m
2026-07-22 UAL941 LHR → EWR Jul 22, 16:00 UTCJul 22, 23:25 UTC7h 25m
2026-07-22 UAL938 ORD → LHR Jul 22, 12:35 UTCJul 22, 14:00 UTC1h 25m
2026-07-21 UAL928 LHR → ORD Jul 21, 13:50 UTCJul 21, 22:10 UTC8h 20m
2026-07-21 UAL938 ORD → LHR Jul 21, 03:20 UTCJul 21, 10:45 UTC7h 25m
2026-07-20 UAL928 LHR → ORD Jul 20, 21:40 UTCJul 20, 21:50 UTC10m
2026-07-20 UAL928 LHR → ORD Jul 20, 13:50 UTCJul 20, 15:05 UTC1h 15m
2026-07-20 UAL928 LHR → ORD Jul 20, 13:34 UTCJul 20, 21:23 UTC7h 49m
2026-07-20 UAL146 EWR → LHR Jul 20, 03:50 UTCJul 20, 10:35 UTC6h 45m
2026-07-17 UAL921 - Jul 17, 17:40 UTCJul 18, 00:55 UTC7h 15m
2026-07-17 UAL921 LHR → EWR Jul 17, 17:22 UTCJul 18, 00:50 UTC7h 28m
2026-07-16 UAL16 EWR → LHR Jul 16, 21:58 UTCJul 17, 04:42 UTC6h 44m
2026-07-16 UAL16 EWR → LHR Jul 16, 22:15 UTCJul 17, 04:44 UTC6h 30m
2026-07-16 UAL17 - Jul 16, 10:15 UTCJul 16, 17:25 UTC7h 10m
2026-07-16 UAL17 LHR → EWR Jul 16, 09:50 UTCJul 16, 17:21 UTC7h 31m
2026-07-16 UAL904 - Jul 16, 00:25 UTCJul 16, 06:45 UTC6h 20m
2026-07-16 UAL904 EWR → LHR Jul 16, 00:35 UTCJul 16, 07:05 UTC6h 30m
2026-07-14 UAL3919 NCE → EWR Jul 14, 21:36 UTCJul 15, 05:26 UTC7h 50m
2026-07-14 UAL3919 NCE → EWR Jul 14, 21:20 UTCJul 15, 05:30 UTC8h 9m
2026-07-13 UAL272 EWR → NCE Jul 13, 00:05 UTCJul 13, 07:45 UTC7h 40m
2026-07-12 UAL147 LHR → EWR Jul 12, 11:35 UTCJul 12, 18:40 UTC7h 5m
2026-07-11 UAL16 EWR → LHR Jul 11, 22:20 UTCJul 12, 04:45 UTC6h 25m
2026-07-11 UAL135 ZRH → EWR Jul 11, 08:35 UTCJul 11, 17:15 UTC8h 40m
2026-07-10 UAL3 ORD → ZRH Jul 10, 21:32 UTCJul 11, 05:30 UTC7h 58m
2026-07-10 UAL3 ORD → ZRH Jul 10, 21:25 UTCJul 11, 05:31 UTC8h 5m
2026-07-10 UAL958 - Jul 10, 07:25 UTCJul 10, 08:40 UTC1h 15m
2026-07-10 UAL958 LHR → ORD Jul 10, 07:19 UTCJul 10, 15:31 UTC8h 12m
2026-07-09 UAL934 - Jul 9, 14:40 UTCJul 9, 21:05 UTC6h 25m
2026-07-08 UAL273 - Jul 8, 10:35 UTCJul 8, 12:05 UTC1h 30m
2026-07-08 UAL273 NCE → EWR Jul 8, 10:30 UTCJul 8, 18:56 UTC8h 26m
2026-07-08 UAL272 - Jul 8, 00:25 UTCJul 8, 01:55 UTC1h 30m
2026-07-08 UAL272 EWR → NCE Jul 8, 00:20 UTCJul 8, 07:47 UTC7h 27m
2026-07-06 UAL1149 EWR → SRQ Jul 6, 14:25 UTCJul 6, 19:20 UTC4h 55m
2026-07-06 UAL1558 EWR → SFO Jul 6, 00:10 UTCJul 6, 06:05 UTC5h 55m
2026-07-02 UAL3865 - Jul 2, 16:45 UTCJul 2, 18:15 UTC1h 30m
2026-06-30 UAL962 EWR → BER Jun 30, 21:43 UTCJun 30, 23:15 UTC1h 32m

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 N661UA page for operator, model, and routing details .

Mode-S A8B9B3 frequently asked

What is Mode-S code A8B9B3?
A8B9B3 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N661UA.
Where is Mode-S A8B9B3 registered?
Mode-S code A8B9B3 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A8B9B3 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A8B9B3, octal 52134663, decimal 11,057,587.
What flights does A8B9B3 operate?
Mode-S A8B9B3 has broadcast 20 distinct callsigns, including UAL135, UAL904, UAL55, UAL134, UAL3.