Apparatus

Try JFK, AAL1290, BAW, or N225AN.

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 4h ago
Flights observed
318
Distinct callsigns
20
Country
US
Last broadcast
4h 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
UAL793 United Airlines 6 2026-06-27
UAL429 - 5 2026-06-23
UAL1637 - 5 2026-06-16
UAL1517 - 5 2026-06-28
UAL822 United Airlines 4 2026-05-28
UAL412 United Airlines 4 2026-05-28
UAL1317 United Airlines 4 2026-06-04
UAL732 - 3 2026-06-17
UAL482 - 3 2026-06-29
UAL265 - 3 2026-06-25
UAL2468 United Airlines 3 2026-06-12
UAL2218 United Airlines 3 2026-05-06
UAL2160 United Airlines 3 2026-06-17
UAL2049 - 3 2026-06-17
UAL1856 United Airlines 3 2026-06-05
UAL1803 - 3 2026-06-24
UAL1795 - 3 2026-06-16
UAL1410 United Airlines 3 2026-06-07
UAL1193 United Airlines 3 2026-05-18
UAL1091 - 3 2026-06-23

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-04 UAL1470 DEN → LEX Jul 4, 23:55 UTCJul 5, 02:15 UTC2h 20m
2026-07-04 UAL1728 - Jul 4, 21:00 UTCJul 4, 22:20 UTC1h 20m
2026-07-04 UAL792 - Jul 4, 18:05 UTCJul 4, 19:10 UTC1h 5m
2026-07-04 UAL255 - Jul 4, 14:35 UTCJul 4, 16:30 UTC1h 55m
2026-07-04 UAL1204 DEN → ATW Jul 4, 00:35 UTCJul 4, 02:20 UTC1h 45m
2026-07-03 UAL259 - Jul 3, 20:05 UTCJul 3, 22:05 UTC2h 0m
2026-07-03 UAL487 SFO → SBP Jul 3, 18:00 UTCJul 3, 18:35 UTC35m
2026-07-03 UAL2818 PDX → SFO Jul 3, 15:35 UTCJul 3, 17:00 UTC1h 25m
2026-07-03 UAL2413 - Jul 3, 06:50 UTCJul 3, 08:10 UTC1h 20m
2026-07-03 UAL436 - Jul 3, 00:35 UTCJul 3, 05:40 UTC5h 5m
2026-07-02 UAL2836 - Jul 2, 15:45 UTCJul 2, 20:10 UTC4h 25m
2026-07-02 UAL2836 SFO → PIT Jul 2, 15:45 UTCJul 2, 20:08 UTC4h 23m
2026-07-02 UAL702 EWR → IAH Jul 2, 13:05 UTCJul 2, 14:25 UTC1h 20m
2026-07-02 UAL1809 - Jul 2, 06:25 UTCJul 2, 07:30 UTC1h 5m
2026-07-02 UAL2850 - Jul 2, 04:05 UTCJul 2, 04:45 UTC40m
2026-07-02 UAL1613 EWR → FLL Jul 2, 00:05 UTCJul 2, 00:40 UTC35m
2026-07-01 UAL1846 - Jul 1, 21:40 UTCJul 1, 22:15 UTC35m
2026-07-01 UAL1846 - Jul 1, 17:55 UTCJul 1, 20:05 UTC2h 10m
2026-07-01 UAL1081 - Jul 1, 14:15 UTCJul 1, 15:55 UTC1h 40m
2026-07-01 UAL1282 - Jul 1, 00:50 UTCJul 1, 02:30 UTC1h 40m
2026-06-29 UAL439 AUS → DEN Jun 29, 23:34 UTCJun 30, 01:19 UTC1h 45m
2026-06-29 UAL1711 - Jun 29, 21:39 UTCJun 29, 22:10 UTC30m
2026-06-29 UAL2190 - Jun 29, 15:09 UTCJun 29, 17:49 UTC2h 40m
2026-06-29 UAL482 ORD → DCA Jun 29, 12:33 UTCJun 29, 13:34 UTC1h 1m
2026-06-29 UAL482 - Jun 29, 12:09 UTCJun 29, 13:39 UTC1h 30m
2026-06-28 UAL623 ORD → ORD Jun 28, 18:05 UTCJun 29, 01:00 UTC6h 55m
2026-06-28 UAL704 - Jun 28, 14:45 UTCJun 28, 16:39 UTC1h 55m
2026-06-28 UAL1269 - Jun 28, 11:45 UTCJun 28, 13:10 UTC1h 25m
2026-06-28 UAL1269 ORD → BWI Jun 28, 11:53 UTCJun 28, 13:05 UTC1h 12m
2026-06-28 UAL1517 DFW → ORD Jun 28, 03:00 UTCJun 28, 04:40 UTC1h 40m
2026-06-28 UAL1517 DFW → ORD Jun 28, 02:30 UTCJun 28, 04:25 UTC1h 55m
2026-06-27 UAL793 SFO → ORD Jun 27, 21:36 UTCJun 27, 23:45 UTC2h 9m
2026-06-27 UAL793 SFO → ORD Jun 27, 21:50 UTCJun 27, 23:55 UTC2h 5m
2026-06-27 UAL1107 SAN → SFO Jun 27, 18:35 UTCJun 27, 19:29 UTC55m
2026-06-27 UAL1107 SAN → SFO Jun 27, 18:37 UTCJun 27, 19:15 UTC38m
2026-06-27 UAL365 ORD → CVG Jun 27, 16:00 UTCJun 27, 16:44 UTC45m
2026-06-27 UAL786 ATL → EWR Jun 27, 12:39 UTCJun 27, 14:09 UTC1h 30m
2026-06-27 UAL2762 - Jun 27, 03:34 UTCJun 27, 04:54 UTC1h 20m
2026-06-27 UAL2762 ORD → ICT Jun 27, 03:28 UTCJun 27, 04:52 UTC1h 24m
2026-06-27 UAL1564 BOS → ORD Jun 27, 00:14 UTCJun 27, 02:04 UTC1h 50m
2026-06-27 UAL1564 BOS → ORD Jun 27, 00:10 UTCJun 27, 01:47 UTC1h 37m
2026-06-26 UAL578 ORD → PHL Jun 26, 21:30 UTCJun 26, 23:00 UTC1h 30m
2026-06-26 UAL1829 EWR → SFO Jun 26, 19:14 UTCJun 26, 19:50 UTC35m
2026-06-26 UAL2847 - Jun 26, 15:45 UTCJun 26, 17:19 UTC1h 35m
2026-06-26 UAL247 DTW → ORD Jun 26, 12:39 UTCJun 26, 13:55 UTC1h 15m
2026-06-26 UAL2317 - Jun 26, 03:29 UTCJun 26, 04:45 UTC1h 15m
2026-06-25 UAL1639 STL → ORD Jun 25, 22:50 UTCJun 25, 23:43 UTC53m
2026-06-25 UAL1639 - Jun 25, 19:59 UTCJun 25, 21:40 UTC1h 40m
2026-06-25 UAL1327 ATL → DEN Jun 25, 15:20 UTCJun 25, 18:19 UTC3h 0m
2026-06-25 UAL1327 ATL → DEN Jun 25, 15:28 UTCJun 25, 18:15 UTC2h 47m

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 4h 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 UAL793, UAL429, UAL1637, UAL1517, UAL822.