Apparatus

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sensors Mode-S transponder

AAAC4A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N787UA · BOEING 777-200 · operated by UNITED AIRLINES INC

Hex
AAAC4A
Octal
52526112
Decimal
11,185,226
Country
US
Tail
N787UA
Type
B772
No current signal · last broadcast Jul 26, 18:50 UTC
Flights observed
279
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 18:50 UTC

Last known position

Most recent position reported by Mode-S AAAC4A.

Country allocation

The ICAO 24-bit address AAAC4A 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
UAL41 United Airlines 11 2026-04-18
UAL40 United Airlines 11 2026-04-18
UAL56 United Airlines 9 2026-07-21
UAL879 - 8 2026-06-17
UAL819 - 8 2026-06-28
UAL990 United Airlines 7 2026-07-25
UAL46 - 7 2026-06-26
UAL34 United Airlines 7 2026-07-25
UAL23 - 7 2026-07-07
UAL943 United Airlines 6 2026-07-20
UAL914 United Airlines 6 2026-07-26
UAL884 United Airlines 6 2026-05-19
UAL880 United Airlines 6 2026-06-29
UAL47 - 6 2026-06-27
UAL35 United Airlines 6 2026-07-24
UAL194 United Airlines 6 2026-06-10
UAL984 United Airlines 5 2026-07-22
UAL948 - 5 2026-06-21
UAL924 - 5 2026-07-19
UAL885 United Airlines 5 2026-05-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL914 CDG → IAD Jul 26, 10:55 UTCJul 26, 18:45 UTC7h 50m
2026-07-25 UAL990 SFO → CDG Jul 25, 22:08 UTCJul 26, 07:34 UTC9h 26m
2026-07-25 UAL990 SFO → CDG Jul 25, 21:55 UTCJul 26, 07:35 UTC9h 41m
2026-07-25 UAL34 KIX → SFO Jul 25, 08:15 UTCJul 25, 17:52 UTC9h 37m
2026-07-25 UAL34 KIX → SFO Jul 25, 08:15 UTCJul 25, 17:47 UTC9h 32m
2026-07-25 UAL34 KIX → SFO Jul 25, 08:15 UTCJul 25, 08:30 UTC15m
2026-07-24 UAL35 SFO → KIX Jul 24, 18:35 UTCJul 25, 05:20 UTC10h 45m
2026-07-24 UAL35 SFO → KIX Jul 24, 18:50 UTCJul 25, 05:10 UTC10h 20m
2026-07-23 UAL59 FRA → SFO Jul 23, 11:40 UTCJul 23, 13:20 UTC1h 40m
2026-07-23 UAL59 FRA → SFO Jul 23, 11:24 UTCJul 23, 22:34 UTC11h 10m
2026-07-22 UAL58 SFO → FRA Jul 22, 21:30 UTCJul 23, 07:35 UTC10h 5m
2026-07-22 UAL984 CDG → SFO Jul 22, 13:45 UTCJul 22, 18:20 UTC4h 35m
2026-07-21 UAL57 EWR → CDG Jul 21, 22:33 UTCJul 22, 05:19 UTC6h 46m
2026-07-21 UAL57 - Jul 21, 22:45 UTCJul 22, 05:25 UTC6h 40m
2026-07-21 UAL56 CDG → EWR Jul 21, 08:20 UTCJul 21, 09:35 UTC1h 15m
2026-07-21 UAL56 CDG → EWR Jul 21, 08:29 UTCJul 21, 15:39 UTC7h 10m
2026-07-21 UAL56 CDG → EWR Jul 21, 08:29 UTCJul 21, 15:36 UTC7h 7m
2026-07-20 UAL915 IAD → CDG Jul 20, 22:50 UTCJul 21, 05:45 UTC6h 54m
2026-07-20 UAL943 LIS → IAD Jul 20, 11:40 UTCJul 20, 18:55 UTC7h 15m
2026-07-20 UAL942 IAD → LIS Jul 20, 03:05 UTCJul 20, 09:20 UTC6h 15m
2026-07-19 UAL925 LHR → IAD Jul 19, 16:30 UTCJul 20, 00:10 UTC7h 40m
2026-07-19 UAL924 - Jul 19, 03:45 UTCJul 19, 06:10 UTC2h 25m
2026-07-19 UAL924 IAD → LHR Jul 19, 03:38 UTCJul 19, 10:57 UTC7h 19m
2026-07-18 UAL914 - Jul 18, 18:25 UTCJul 18, 18:50 UTC25m
2026-07-18 UAL914 - Jul 18, 10:40 UTCJul 18, 12:15 UTC1h 35m
2026-07-18 UAL914 CDG → IAD Jul 18, 10:49 UTCJul 18, 18:07 UTC7h 18m
2026-07-18 UAL914 CDG → IAD Jul 18, 10:49 UTCJul 18, 18:43 UTC7h 54m
2026-07-17 UAL990 SFO → CDG Jul 17, 22:23 UTCJul 18, 08:08 UTC9h 45m
2026-07-17 UAL990 - Jul 17, 22:25 UTCJul 18, 08:10 UTC9h 46m
2026-07-16 UAL506 - Jul 16, 14:25 UTCJul 17, 02:50 UTC12h 25m
2026-07-16 UAL507 SFO → FCO Jul 16, 00:19 UTCJul 16, 11:19 UTC11h 0m
2026-07-16 UAL507 - Jul 16, 00:15 UTCJul 16, 08:30 UTC8h 15m
2026-07-15 UAL195 - Jul 15, 10:05 UTCJul 15, 21:25 UTC11h 20m
2026-07-14 UAL102 - Jul 14, 22:10 UTCJul 15, 06:30 UTC8h 19m
2026-07-14 UAL102 IAH → MUC Jul 14, 22:02 UTCJul 15, 07:54 UTC9h 52m
2026-07-13 UAL4 - Jul 13, 13:10 UTCJul 13, 22:35 UTC9h 25m
2026-07-13 UAL924 IAD → LHR Jul 13, 02:35 UTCJul 13, 09:30 UTC6h 55m
2026-07-12 UAL943 LIS → IAD Jul 12, 13:48 UTCJul 12, 20:49 UTC7h 1m
2026-07-12 UAL943 LIS → IAD Jul 12, 13:48 UTCJul 12, 20:53 UTC7h 5m
2026-07-12 UAL943 - Jul 12, 13:40 UTCJul 12, 14:15 UTC35m
2026-07-12 UAL942 IAD → LIS Jul 12, 04:53 UTCJul 12, 11:19 UTC6h 26m
2026-07-12 UAL942 IAD → LIS Jul 12, 05:10 UTCJul 12, 11:25 UTC6h 15m
2026-07-11 UAL943 LIS → IAD Jul 11, 11:46 UTCJul 11, 19:00 UTC7h 14m
2026-07-11 UAL943 LIS → IAD Jul 11, 11:45 UTCJul 11, 19:05 UTC7h 20m
2026-07-11 UAL942 IAD → LIS Jul 11, 03:30 UTCJul 11, 09:55 UTC6h 25m
2026-07-10 UAL933 FRA → IAD Jul 10, 15:50 UTCJul 11, 00:30 UTC8h 40m
2026-07-10 UAL933 FRA → IAD Jul 10, 15:35 UTCJul 11, 00:30 UTC8h 55m
2026-07-10 UAL932 IAD → FRA Jul 10, 03:10 UTCJul 10, 10:15 UTC7h 5m
2026-07-09 UAL914 - Jul 9, 10:50 UTCJul 9, 19:05 UTC8h 15m
2026-07-08 UAL990 SFO → CDG Jul 8, 22:20 UTCJul 9, 08:25 UTC10h 5m

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 N787UA page for operator, model, and routing details .

Mode-S AAAC4A frequently asked

What is Mode-S code AAAC4A?
AAAC4A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N787UA.
Where is Mode-S AAAC4A registered?
Mode-S code AAAC4A 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 AAAC4A broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 18:50 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AAAC4A, octal 52526112, decimal 11,185,226.
What flights does AAAC4A operate?
Mode-S AAAC4A has broadcast 20 distinct callsigns, including UAL41, UAL40, UAL56, UAL879, UAL819.