Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A1A2A2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N204UA · BOEING 777-200 · operated by UNITED AIRLINES INC

Hex
A1A2A2
Octal
50321242
Decimal
10,592,930
Country
US
Tail
N204UA
Type
B772
No current signal · last broadcast Jul 26, 20:50 UTC
Flights observed
252
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:50 UTC

Last known position

Most recent position reported by Mode-S A1A2A2.

Country allocation

The ICAO 24-bit address A1A2A2 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
UAL888 United Airlines 12 2026-07-25
UAL18 - 12 2026-07-04
UAL19 - 11 2026-07-03
UAL905 - 9 2026-06-26
UAL2397 United Airlines 9 2026-05-12
UAL14 - 9 2026-07-10
UAL819 United Airlines 8 2026-05-14
UAL889 United Airlines 7 2026-07-26
UAL46 United Airlines 7 2026-05-20
UAL2238 United Airlines 7 2026-05-11
UAL984 - 6 2026-06-22
UAL939 United Airlines 6 2026-04-17
UAL818 United Airlines 6 2026-05-15
UAL47 United Airlines 6 2026-05-20
UAL22 United Airlines 6 2026-06-27
UAL194 United Airlines 6 2026-06-08
UAL160 United Airlines 6 2026-06-09
UAL926 United Airlines 5 2026-07-24
UAL879 - 5 2026-07-20
UAL5 United Airlines 5 2026-05-06

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL889 PEK → SFO Jul 26, 10:30 UTCJul 26, 12:25 UTC1h 55m
2026-07-26 UAL889 PEK → SFO Jul 26, 03:40 UTCJul 26, 20:40 UTC17h 1m
2026-07-25 UAL888 SFO → PEK Jul 25, 18:15 UTCJul 26, 06:56 UTC12h 41m
2026-07-25 UAL888 SFO → PEK Jul 25, 18:25 UTCJul 26, 05:55 UTC11h 30m
2026-07-24 UAL927 FRA → SFO Jul 24, 16:00 UTCJul 25, 03:15 UTC11h 15m
2026-07-24 UAL927 FRA → SFO Jul 24, 15:51 UTCJul 25, 03:11 UTC11h 20m
2026-07-24 UAL926 SFO → FRA Jul 24, 02:44 UTCJul 24, 12:28 UTC9h 44m
2026-07-24 UAL926 SFO → FRA Jul 24, 02:30 UTCJul 24, 10:10 UTC7h 40m
2026-07-23 UAL45 ZRH → SFO Jul 23, 12:15 UTCJul 24, 00:00 UTC11h 45m
2026-07-22 UAL44 SFO → ZRH Jul 22, 22:05 UTCJul 23, 08:20 UTC10h 15m
2026-07-21 UAL195 - Jul 21, 10:00 UTCJul 21, 21:20 UTC11h 20m
2026-07-20 UAL102 IAH → MUC Jul 20, 22:10 UTCJul 21, 07:45 UTC9h 34m
2026-07-20 UAL879 - Jul 20, 10:10 UTCJul 20, 19:20 UTC9h 10m
2026-07-20 UAL879 LHR → IAH Jul 20, 10:00 UTCJul 20, 19:08 UTC9h 8m
2026-07-20 UAL918 IAD → LHR Jul 20, 01:06 UTCJul 20, 07:44 UTC6h 38m
2026-07-20 UAL918 IAD → LHR Jul 20, 00:55 UTCJul 20, 07:55 UTC7h 0m
2026-07-19 UAL943 LIS → IAD Jul 19, 14:30 UTCJul 19, 22:00 UTC7h 30m
2026-07-19 UAL942 IAD → LIS Jul 19, 04:55 UTCJul 19, 11:30 UTC6h 35m
2026-07-18 UAL933 FRA → IAD Jul 18, 16:05 UTCJul 19, 00:20 UTC8h 15m
2026-07-18 UAL926 SFO → FRA Jul 18, 03:20 UTCJul 18, 13:10 UTC9h 50m
2026-07-17 UAL45 ZRH → SFO Jul 17, 13:12 UTCJul 18, 00:26 UTC11h 14m
2026-07-17 UAL45 - Jul 17, 13:00 UTCJul 17, 15:10 UTC2h 10m
2026-07-16 UAL44 SFO → ZRH Jul 16, 22:00 UTCJul 17, 08:15 UTC10h 15m
2026-07-14 UAL195 - Jul 14, 10:25 UTCJul 14, 21:45 UTC11h 20m
2026-07-13 UAL102 - Jul 13, 22:25 UTCJul 14, 08:15 UTC9h 50m
2026-07-11 UAL879 LHR → IAH Jul 11, 09:25 UTCJul 11, 19:03 UTC9h 38m
2026-07-11 UAL879 - Jul 11, 09:25 UTCJul 11, 19:05 UTC9h 40m
2026-07-10 UAL14 EWR → LHR Jul 10, 23:35 UTCJul 11, 05:27 UTC5h 52m
2026-07-10 UAL14 - Jul 10, 23:25 UTCJul 11, 00:30 UTC1h 5m
2026-07-10 UAL56 - Jul 10, 08:30 UTCJul 10, 16:10 UTC7h 40m
2026-07-09 UAL915 IAD → CDG Jul 9, 23:05 UTCJul 10, 06:15 UTC7h 10m
2026-07-09 UAL804 HND → IAD Jul 9, 07:20 UTCJul 9, 20:15 UTC12h 55m
2026-07-08 UAL875 SFO → HND Jul 8, 18:40 UTCJul 9, 05:00 UTC10h 20m
2026-07-07 UAL673 - Jul 7, 14:40 UTCJul 7, 17:00 UTC2h 20m
2026-07-07 UAL673 BCN → SFO Jul 7, 14:36 UTCJul 8, 02:10 UTC11h 34m
2026-07-07 UAL673 BCN → SFO Jul 7, 14:36 UTCJul 8, 02:10 UTC11h 34m
2026-07-07 UAL672 - Jul 7, 01:25 UTCJul 7, 12:10 UTC10h 45m
2026-07-06 UAL195 MUC → SFO Jul 6, 10:05 UTCJul 6, 21:25 UTC11h 20m
2026-07-05 UAL102 - Jul 5, 22:00 UTCJul 6, 07:35 UTC9h 35m
2026-07-05 UAL879 - Jul 5, 09:40 UTCJul 5, 19:00 UTC9h 20m
2026-07-04 UAL14 - Jul 4, 23:35 UTCJul 5, 05:45 UTC6h 10m
2026-07-04 UAL18 MXP → EWR Jul 4, 08:06 UTCJul 4, 16:25 UTC8h 19m
2026-07-04 UAL18 MXP → EWR Jul 4, 08:05 UTCJul 4, 16:25 UTC8h 20m
2026-07-03 UAL19 EWR → MXP Jul 3, 22:03 UTCJul 4, 05:27 UTC7h 24m
2026-07-03 UAL19 - Jul 3, 22:20 UTCJul 3, 23:55 UTC1h 35m
2026-07-02 UAL3038 - Jul 2, 16:05 UTCJul 2, 17:55 UTC1h 50m
2026-07-02 UAL3038 FRA → EWR Jul 2, 15:50 UTCJul 3, 00:05 UTC8h 15m
2026-07-02 UAL3037 - Jul 2, 06:20 UTCJul 2, 13:05 UTC6h 45m
2026-06-29 UAL1333 SFO → EWR Jun 29, 21:14 UTCJun 30, 01:55 UTC4h 41m
2026-06-29 UAL1593 - Jun 29, 14:04 UTCJun 29, 19:24 UTC5h 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 N204UA page for operator, model, and routing details .

Mode-S A1A2A2 frequently asked

What is Mode-S code A1A2A2?
A1A2A2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N204UA.
Where is Mode-S A1A2A2 registered?
Mode-S code A1A2A2 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 A1A2A2 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 20:50 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1A2A2, octal 50321242, decimal 10,592,930.
What flights does A1A2A2 operate?
Mode-S A1A2A2 has broadcast 20 distinct callsigns, including UAL888, UAL18, UAL19, UAL905, UAL2397.