Apparatus

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sensors Mode-S transponder

AB3655

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N821UA · AIRBUS A-319 · operated by UNITED AIRLINES INC

Hex
AB3655
Octal
52633125
Decimal
11,220,565
Country
US
Tail
N821UA
Type
A319
No current signal · last broadcast 16m ago
Flights observed
79
Distinct callsigns
20
Country
US
Last broadcast
16m ago

Last known position

Most recent position reported by Mode-S AB3655.

Country allocation

The ICAO 24-bit address AB3655 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
UAL2218 United Airlines 3 2026-05-06
UAL1193 United Airlines 3 2026-05-18
UAL793 United Airlines 2 2026-05-03
UAL664 United Airlines 2 2026-05-09
UAL597 United Airlines 2 2026-05-18
UAL582 United Airlines 2 2026-05-07
UAL497 United Airlines 2 2026-05-18
UAL429 United Airlines 2 2026-05-13
UAL4202 United Airlines 2 2026-05-03
UAL2270 United Airlines 2 2026-05-17
UAL2249 United Airlines 2 2026-05-07
UAL2201 United Airlines 2 2026-05-15
UAL2173 United Airlines 2 2026-05-20
UAL2133 United Airlines 2 2026-05-05
UAL2042 United Airlines 2 2026-05-12
UAL1565 United Airlines 2 2026-05-19
UAL1532 United Airlines 2 2026-05-14
UAL1239 United Airlines 2 2026-05-08
UAL1060 United Airlines 2 2026-05-13
UAL745 United Airlines 1 2026-05-07

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-05-20 UAL1510 IAD → PHX May 20, 20:50 UTCMay 20, 23:15 UTC2h 25m
2026-05-20 UAL1479 IAD → EWR May 20, 16:10 UTCMay 20, 18:15 UTC2h 5m
2026-05-20 UAL2255 MSO → DEN May 20, 13:25 UTCMay 20, 13:45 UTC20m
2026-05-20 UAL2173 MYR → ORD May 20, 01:40 UTCMay 20, 01:55 UTC15m
2026-05-20 UAL2173 MYR → ORD May 20, 01:40 UTCMay 20, 02:07 UTC27m
2026-05-19 UAL1588 EWR → SAV May 19, 20:30 UTCMay 19, 23:15 UTC2h 45m
2026-05-19 UAL2041 SFO → SAN May 19, 16:25 UTCMay 19, 18:50 UTC2h 25m
2026-05-19 UAL731 TPA → SFO May 19, 12:55 UTCMay 19, 14:25 UTC1h 30m
2026-05-19 UAL1565 SFO → PHX May 19, 01:26 UTCMay 19, 02:36 UTC1h 10m
2026-05-19 UAL1565 SFO → PHX May 19, 01:15 UTCMay 19, 02:45 UTC1h 30m
2026-05-18 UAL484 DEN → LAS May 18, 20:50 UTCMay 19, 00:15 UTC3h 25m
2026-05-18 UAL597 EWR → LAS May 18, 17:15 UTCMay 18, 18:25 UTC1h 10m
2026-05-18 UAL497 CVG → DEN May 18, 14:15 UTCMay 18, 15:20 UTC1h 5m
2026-05-18 UAL1193 IAH → SFO May 18, 03:01 UTCMay 18, 03:05 UTC5m
2026-05-17 UAL1193 IAH → SFO May 17, 23:45 UTCMay 18, 03:05 UTC3h 20m
2026-05-17 UAL1193 IAH → SFO May 17, 23:43 UTCMay 18, 02:45 UTC3h 2m
2026-05-17 UAL1697 ATL → EWR May 17, 17:20 UTCMay 17, 19:30 UTC2h 10m
2026-05-17 UAL2270 LAS → IAH May 17, 12:05 UTCMay 17, 15:35 UTC3h 30m
2026-05-17 UAL680 SAT → DEN May 17, 00:10 UTCMay 17, 03:30 UTC3h 20m
2026-05-16 UAL2604 SFO → LAX May 16, 21:40 UTCMay 16, 22:00 UTC20m
2026-05-16 UAL2482 SFO → HNL May 16, 19:55 UTCMay 16, 20:15 UTC20m
2026-05-15 UAL2201 ONT → SFO May 15, 23:25 UTCMay 16, 02:00 UTC2h 35m
2026-05-15 UAL2201 ONT → SFO May 15, 23:06 UTCMay 16, 01:50 UTC2h 44m
2026-05-15 UAL499K SFO → BNA May 15, 17:20 UTCMay 15, 21:20 UTC4h 0m
2026-05-15 UAL1597 LAX → SFO May 15, 11:10 UTCMay 15, 15:55 UTC4h 44m
2026-05-14 UAL2086 EWR → ATL May 14, 23:55 UTCMay 15, 02:10 UTC2h 15m
2026-05-14 UAL1532 SLC → EWR May 14, 20:55 UTCMay 14, 21:45 UTC50m
2026-05-14 UAL1532 SLC → EWR May 14, 20:59 UTCMay 14, 21:41 UTC42m
2026-05-14 UAL2468 TPA → EWR May 14, 16:55 UTCMay 14, 19:35 UTC2h 40m
2026-05-14 UAL499 DEN → EWR May 14, 01:00 UTCMay 14, 02:50 UTC1h 50m
2026-05-13 UAL1478 SEA → SFO May 13, 21:35 UTCMay 13, 23:20 UTC1h 45m
2026-05-13 UAL1091 MEX → IAH May 13, 17:55 UTCMay 13, 19:45 UTC1h 50m
2026-05-13 UAL1060 IAH → MEX May 13, 14:40 UTCMay 13, 16:30 UTC1h 50m
2026-05-13 UAL1060 IAH → MEX May 13, 14:46 UTCMay 13, 16:25 UTC1h 39m
2026-05-13 UAL1085 MEX → IAH May 13, 11:10 UTCMay 13, 12:55 UTC1h 45m
2026-05-13 UAL429 IAH → MEX May 13, 03:10 UTCMay 13, 05:00 UTC1h 50m
2026-05-12 UAL659 EWR → IAD May 12, 21:20 UTCMay 12, 23:40 UTC2h 20m
2026-05-12 UAL2042 ORD → BDL May 12, 17:50 UTCMay 12, 19:45 UTC1h 55m
2026-05-12 UAL2042 ORD → BDL May 12, 18:01 UTCMay 12, 19:43 UTC1h 42m
2026-05-12 UAL428 MEX → IAH May 12, 13:05 UTCMay 12, 14:50 UTC1h 45m
2026-05-12 UAL429 IAH → MEX May 12, 02:55 UTCMay 12, 04:50 UTC1h 55m
2026-05-11 UAL1444 SFO → IAH May 11, 21:05 UTCMay 11, 22:35 UTC1h 29m
2026-05-11 UAL315 FLL → IAD May 11, 17:25 UTCMay 11, 19:35 UTC2h 10m
2026-05-11 UAL1326 SFO → BNA May 11, 14:40 UTCMay 11, 15:10 UTC30m
2026-05-10 UAL2270 LAS → IAH May 10, 19:54 UTCMay 10, 21:44 UTC1h 50m
2026-05-10 UAL597 EWR → LAS May 10, 17:10 UTCMay 10, 18:09 UTC1h 0m
2026-05-10 UAL497 CVG → DEN May 10, 14:04 UTCMay 10, 15:15 UTC1h 10m
2026-05-10 UAL355 BUR → SFO May 10, 11:15 UTCMay 10, 12:49 UTC1h 35m
2026-05-09 UAL664 LAS → ORD May 9, 22:18 UTCMay 9, 23:07 UTC49m
2026-05-09 UAL664 LAS → ORD May 9, 22:00 UTCMay 9, 23:09 UTC1h 10m

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 N821UA page for operator, model, and routing details .

Mode-S AB3655 frequently asked

What is Mode-S code AB3655?
AB3655 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N821UA.
Where is Mode-S AB3655 registered?
Mode-S code AB3655 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 AB3655 broadcasting right now?
No active broadcast right now. Last signal was 16m ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AB3655, octal 52633125, decimal 11,220,565.
What flights does AB3655 operate?
Mode-S AB3655 has broadcast 20 distinct callsigns, including UAL2218, UAL1193, UAL793, UAL664, UAL597.