Apparatus

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sensors Mode-S transponder

A56661

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N447UA · AIRBUS A-320 · operated by UNITED AIRLINES INC

Hex
A56661
Octal
51263141
Decimal
10,839,649
Country
US
Tail
N447UA
Type
A320
No current signal · last broadcast Jul 26, 20:40 UTC
Flights observed
494
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:40 UTC

Last known position

Most recent position reported by Mode-S A56661.

Country allocation

The ICAO 24-bit address A56661 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
UAL1838 - 10 2026-07-16
UAL1088 - 9 2026-07-16
UAL2831 United Airlines 8 2026-07-19
UAL1702 United Airlines 6 2026-07-19
UAL790 United Airlines 5 2026-06-13
UAL442 - 5 2026-06-12
UAL355 - 5 2026-06-29
UAL2090 United Airlines 5 2026-04-27
UAL1360 United Airlines 5 2026-04-29
UAL732 United Airlines 4 2026-05-14
UAL725 United Airlines 4 2026-05-11
UAL2742 United Airlines 4 2026-06-30
UAL2473 - 4 2026-06-27
UAL2082 - 4 2026-06-28
UAL1728 - 4 2026-07-02
UAL1438 United Airlines 4 2026-04-28
UAL1402 - 4 2026-06-20
UAL1216 - 4 2026-07-09
UAL1094 - 4 2026-06-30
UAL1003 United Airlines 4 2026-06-03

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL623 LGA → ORD Jul 26, 18:20 UTCJul 26, 20:40 UTC2h 20m
2026-07-26 UAL704 IAH → EWR Jul 26, 14:40 UTCJul 26, 16:20 UTC1h 40m
2026-07-26 UAL1269 LGA → IAH Jul 26, 11:45 UTCJul 26, 13:15 UTC1h 30m
2026-07-25 UAL1744 IAD → ORD Jul 25, 01:40 UTCJul 25, 03:35 UTC1h 55m
2026-07-24 UAL623 LGA → ORD Jul 24, 18:00 UTCJul 24, 20:25 UTC2h 25m
2026-07-24 UAL623 LGA → ORD Jul 24, 18:14 UTCJul 24, 20:43 UTC2h 29m
2026-07-24 UAL786 - Jul 24, 12:30 UTCJul 24, 13:55 UTC1h 25m
2026-07-24 UAL786 ICT → ORD Jul 24, 12:45 UTCJul 24, 14:09 UTC1h 24m
2026-07-24 UAL2762 SFO → FTW Jul 24, 02:40 UTCJul 24, 03:55 UTC1h 15m
2026-07-24 UAL2762 SFO → FTW Jul 24, 02:53 UTCJul 24, 03:53 UTC1h 0m
2026-07-23 UAL1625 EWR → DEN Jul 23, 23:15 UTCJul 23, 23:40 UTC25m
2026-07-23 UAL1625 EWR → DEN Jul 23, 21:00 UTCJul 23, 23:40 UTC2h 40m
2026-07-23 UAL1625 EWR → DEN Jul 23, 20:51 UTCJul 23, 22:59 UTC2h 8m
2026-07-23 UAL1061 SEA → SFO Jul 23, 17:15 UTCJul 23, 19:25 UTC2h 10m
2026-07-22 UAL1476 DEN → EUG Jul 22, 23:50 UTCJul 23, 01:10 UTC1h 20m
2026-07-22 UAL1476 DEN → EUG Jul 22, 23:50 UTCJul 23, 00:50 UTC1h 0m
2026-07-22 UAL2207 ORD → PIT Jul 22, 21:15 UTCJul 22, 22:20 UTC1h 5m
2026-07-22 UAL2605 - Jul 22, 19:20 UTCJul 22, 19:30 UTC10m
2026-07-22 UAL2605 - Jul 22, 18:35 UTCJul 22, 19:30 UTC55m
2026-07-22 UAL2605 TVC → ORD Jul 22, 18:35 UTCJul 22, 19:04 UTC29m
2026-07-22 UAL2807 ORD → ORF Jul 22, 16:30 UTCJul 22, 17:05 UTC35m
2026-07-21 UAL1660 ANC → EWR Jul 21, 16:05 UTCJul 21, 16:35 UTC30m
2026-07-21 UAL2093 - Jul 21, 14:10 UTCJul 21, 14:35 UTC25m
2026-07-21 UAL224 ORD → EWR Jul 21, 11:20 UTCJul 21, 13:10 UTC1h 50m
2026-07-21 UAL1583 IAH → LGA Jul 21, 00:00 UTCJul 21, 01:25 UTC1h 25m
2026-07-20 UAL2792 IAD → SFO Jul 20, 21:05 UTCJul 20, 22:10 UTC1h 5m
2026-07-20 UAL561 - Jul 20, 18:55 UTCJul 20, 20:00 UTC1h 5m
2026-07-20 UAL1114 DFW → ORD Jul 20, 15:05 UTCJul 20, 17:00 UTC1h 55m
2026-07-20 UAL2478 SAN → ORD Jul 20, 02:55 UTCJul 20, 06:00 UTC3h 5m
2026-07-19 UAL1702 BDL → IAH Jul 19, 20:25 UTCJul 20, 01:30 UTC5h 5m
2026-07-19 UAL2831 SEA → SFO Jul 19, 17:05 UTCJul 19, 18:45 UTC1h 40m
2026-07-19 UAL2831 SEA → SFO Jul 19, 16:33 UTCJul 19, 18:42 UTC2h 9m
2026-07-18 UAL2205 - Jul 18, 15:20 UTCJul 18, 19:15 UTC3h 55m
2026-07-18 UAL2205 - Jul 18, 10:45 UTCJul 18, 12:55 UTC2h 10m
2026-07-18 UAL1492 ORD → CMH Jul 18, 04:35 UTCJul 18, 05:25 UTC50m
2026-07-18 UAL1492 ORD → CMH Jul 18, 04:28 UTCJul 18, 05:24 UTC56m
2026-07-18 UAL1084 - Jul 18, 01:10 UTCJul 18, 02:19 UTC1h 10m
2026-07-17 UAL1934 - Jul 17, 19:45 UTCJul 17, 22:15 UTC2h 30m
2026-07-17 UAL1366 IAD → DEN Jul 17, 16:19 UTCJul 17, 17:50 UTC1h 30m
2026-07-17 UAL2174 - Jul 17, 12:55 UTCJul 17, 14:30 UTC1h 35m
2026-07-17 UAL1966 - Jul 17, 10:35 UTCJul 17, 11:04 UTC30m
2026-07-17 UAL8154 YUL → EWR Jul 17, 00:25 UTCJul 17, 00:55 UTC30m
2026-07-16 UAL1838 - Jul 16, 20:39 UTCJul 16, 22:25 UTC1h 45m
2026-07-16 UAL1088 - Jul 16, 17:14 UTCJul 16, 19:05 UTC1h 50m
2026-07-16 UAL2196 - Jul 16, 15:00 UTCJul 16, 15:40 UTC40m
2026-07-16 UAL2016 - Jul 16, 12:55 UTCJul 16, 13:20 UTC25m
2026-07-16 UAL2016 IAH → AUS Jul 16, 12:54 UTCJul 16, 13:20 UTC26m
2026-07-16 UAL1966 - Jul 16, 10:40 UTCJul 16, 11:10 UTC30m
2026-07-16 UAL2674 - Jul 16, 00:50 UTCJul 16, 01:20 UTC30m
2026-07-15 UAL1838 - Jul 15, 20:35 UTCJul 15, 22:35 UTC2h 0m

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 N447UA page for operator, model, and routing details .

Mode-S A56661 frequently asked

What is Mode-S code A56661?
A56661 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N447UA.
Where is Mode-S A56661 registered?
Mode-S code A56661 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 A56661 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 20:40 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A56661, octal 51263141, decimal 10,839,649.
What flights does A56661 operate?
Mode-S A56661 has broadcast 20 distinct callsigns, including UAL1838, UAL1088, UAL2831, UAL1702, UAL790.