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 23d ago
Flights observed
403
Distinct callsigns
20
Country
US
Last broadcast
23d 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
UAL1637 United Airlines 6 2026-07-26
UAL429 - 5 2026-06-23
UAL1517 - 5 2026-06-28
UAL822 United Airlines 4 2026-05-28
UAL732 - 4 2026-07-12
UAL412 United Airlines 4 2026-05-28
UAL2836 United Airlines 4 2026-07-23
UAL1846 - 4 2026-07-05
UAL1317 United Airlines 4 2026-06-04
UAL1183 - 4 2026-07-13
UAL642 - 3 2026-07-10
UAL482 - 3 2026-06-29
UAL404 United Airlines 3 2026-07-21
UAL283 - 3 2026-07-12
UAL2818 United Airlines 3 2026-07-24
UAL265 - 3 2026-06-25
UAL259 - 3 2026-07-09
UAL2468 United Airlines 3 2026-06-12
UAL2266 United Airlines 3 2026-07-22

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2289 PDX → SFO Jul 26, 19:30 UTCJul 26, 21:15 UTC1h 45m
2026-07-26 UAL1637 PHX → EWR Jul 26, 15:50 UTCJul 26, 17:50 UTC2h 0m
2026-07-26 UAL2183 SFO → EWR Jul 26, 12:05 UTCJul 26, 14:35 UTC2h 30m
2026-07-26 UAL2100 SAV → EWR Jul 26, 00:00 UTCJul 26, 04:20 UTC4h 20m
2026-07-25 UAL1289 EWR → ATL Jul 25, 15:25 UTCJul 25, 21:00 UTC5h 35m
2026-07-24 UAL402 EWR → BOS Jul 24, 22:30 UTCJul 25, 01:30 UTC3h 0m
2026-07-24 UAL2842 SFO → DFW Jul 24, 18:00 UTCJul 24, 21:05 UTC3h 5m
2026-07-24 UAL2818 PDX → SFO Jul 24, 15:15 UTCJul 24, 16:50 UTC1h 35m
2026-07-24 UAL2818 PDX → SFO Jul 24, 15:07 UTCJul 24, 16:40 UTC1h 33m
2026-07-24 UAL2413 EWR → DFW Jul 24, 05:25 UTCJul 24, 06:35 UTC1h 10m
2026-07-23 UAL436 SFO → BWI Jul 23, 22:30 UTCJul 24, 03:45 UTC5h 15m
2026-07-23 UAL2836 SFO → PIT Jul 23, 15:50 UTCJul 23, 20:10 UTC4h 20m
2026-07-23 UAL1429 IAH → EWR Jul 23, 02:55 UTCJul 23, 06:10 UTC3h 15m
2026-07-23 UAL1429 IAH → EWR Jul 23, 02:42 UTCJul 23, 06:08 UTC3h 26m
2026-07-22 UAL2057 IAH → BZN Jul 22, 22:35 UTCJul 23, 00:50 UTC2h 15m
2026-07-22 UAL688 IAD → BOS Jul 22, 17:40 UTCJul 22, 19:35 UTC1h 55m
2026-07-22 UAL2266 LAS → EWR Jul 22, 13:10 UTCJul 22, 14:40 UTC1h 30m
2026-07-22 UAL2140 SFO → IAH Jul 22, 00:30 UTCJul 22, 01:20 UTC50m
2026-07-21 UAL404 SFO → DEN Jul 21, 22:30 UTCJul 21, 23:10 UTC40m
2026-07-21 UAL404 SFO → DEN Jul 21, 22:28 UTCJul 21, 23:05 UTC37m
2026-07-21 UAL591 SEA → EWR Jul 21, 16:25 UTCJul 21, 19:45 UTC3h 20m
2026-07-21 UAL591 SEA → EWR Jul 21, 14:56 UTCJul 21, 19:45 UTC4h 49m
2026-07-21 UAL299 EWR → RSW Jul 21, 10:25 UTCJul 21, 12:05 UTC1h 40m
2026-07-21 UAL1287 - Jul 21, 00:15 UTCJul 21, 02:00 UTC1h 45m
2026-07-21 UAL1287 EWR → ATL Jul 21, 00:20 UTCJul 21, 01:59 UTC1h 39m
2026-07-20 UAL3898 ATL → DTW Jul 20, 18:15 UTCJul 20, 19:05 UTC50m
2026-07-17 UAL688 - Jul 17, 17:44 UTCJul 17, 19:49 UTC2h 5m
2026-07-17 UAL2266 - Jul 17, 13:20 UTCJul 17, 14:50 UTC1h 30m
2026-07-17 UAL2260 PHL → ORD Jul 17, 11:15 UTCJul 17, 11:55 UTC40m
2026-07-17 UAL1949 - Jul 17, 02:50 UTCJul 17, 03:30 UTC40m
2026-07-16 UAL2407 - Jul 16, 21:10 UTCJul 16, 23:29 UTC2h 20m
2026-07-16 UAL2407 RDU → IAH Jul 16, 21:06 UTCJul 16, 23:25 UTC2h 19m
2026-07-16 UAL2196 - Jul 16, 17:30 UTCJul 16, 19:55 UTC2h 25m
2026-07-16 UAL2460 - Jul 16, 13:00 UTCJul 16, 15:25 UTC2h 25m
2026-07-16 UAL2378 - Jul 16, 01:55 UTCJul 16, 04:10 UTC2h 15m
2026-07-15 UAL1785 - Jul 15, 21:20 UTCJul 16, 00:05 UTC2h 45m
2026-07-15 UAL654 - Jul 15, 17:15 UTCJul 15, 20:10 UTC2h 55m
2026-07-15 UAL1785 - Jul 15, 00:00 UTCJul 15, 02:40 UTC2h 40m
2026-07-14 UAL654 - Jul 14, 20:25 UTCJul 14, 23:05 UTC2h 39m
2026-07-14 UAL1586 - Jul 14, 16:10 UTCJul 14, 16:55 UTC45m
2026-07-14 UAL1586 DFW → IAH Jul 14, 16:11 UTCJul 14, 16:51 UTC40m
2026-07-14 UAL358 - Jul 14, 13:15 UTCJul 14, 14:30 UTC1h 15m
2026-07-14 UAL358 DFW → IAD Jul 14, 12:42 UTCJul 14, 14:27 UTC1h 45m
2026-07-14 UAL313 - Jul 14, 03:05 UTCJul 14, 03:50 UTC45m
2026-07-14 UAL2140 - Jul 14, 01:15 UTCJul 14, 02:05 UTC50m
2026-07-14 UAL2140 IAH → MSY Jul 14, 01:21 UTCJul 14, 01:59 UTC38m
2026-07-13 UAL750 - Jul 13, 20:10 UTCJul 13, 23:50 UTC3h 40m
2026-07-13 UAL537 - Jul 13, 15:00 UTCJul 13, 18:45 UTC3h 45m
2026-07-13 UAL2670 - Jul 13, 12:40 UTCJul 13, 13:25 UTC45m
2026-07-13 UAL1183 - Jul 13, 04:55 UTCJul 13, 06:05 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 23d 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, UAL1637, UAL429, UAL1517, UAL822.