Apparatus

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sensors Mode-S transponder

A0566A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N12021 · BOEING 787-10 Dreamliner · operated by UNITED AIRLINES INC

Hex
A0566A
Octal
50053152
Decimal
10,507,882
Country
US
Tail
N12021
Type
B78X
Broadcasting now · callsign UAL844 · 37,000 ft
Flights observed
111
Distinct callsigns
20
Country
US
Last broadcast
2h ago

Current position

A0566A is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A0566A 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
UAL971 United Airlines 10 2026-06-14
UAL423 - 8 2026-06-15
UAL416 United Airlines 8 2026-06-08
UAL415 United Airlines 8 2026-06-08
UAL970 United Airlines 7 2026-06-13
UAL945 United Airlines 6 2026-05-23
UAL944 United Airlines 6 2026-05-22
UAL422 - 6 2026-06-14
UAL972 - 4 2026-06-12
UAL882 United Airlines 4 2026-06-05
UAL845 United Airlines 4 2026-06-16
UAL995 United Airlines 3 2026-06-12
UAL973 United Airlines 3 2026-06-13
UAL844 - 3 2026-06-17
UAL994 United Airlines 2 2026-06-13
UAL986 United Airlines 2 2026-05-08
UAL881 United Airlines 2 2026-06-04
UAL3937 United Airlines 2 2026-05-01
UAL38 United Airlines 2 2026-05-13
UAL353 United Airlines 2 2026-05-14

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-17 UAL844 - Jun 17, 01:35 UTCJun 17, 07:20 UTC5h 45m
2026-06-16 UAL845 ORD → GRU Jun 16, 04:05 UTCJun 16, 13:30 UTC9h 25m
2026-06-15 UAL423 - Jun 15, 20:50 UTCJun 15, 20:59 UTC10m
2026-06-15 UAL423 ATH → ORD Jun 15, 10:20 UTCJun 15, 20:31 UTC10h 11m
2026-06-15 UAL423 ATH → ORD Jun 15, 10:15 UTCJun 15, 20:59 UTC10h 45m
2026-06-14 UAL422 - Jun 14, 22:25 UTCJun 15, 08:04 UTC9h 39m
2026-06-14 UAL422 ORD → ATH Jun 14, 21:53 UTCJun 15, 08:05 UTC10h 12m
2026-06-14 UAL971 FCO → ORD Jun 14, 08:10 UTCJun 14, 17:30 UTC9h 20m
2026-06-13 UAL970 ORD → FCO Jun 13, 21:05 UTCJun 14, 05:20 UTC8h 15m
2026-06-13 UAL973 BRU → ORD Jun 13, 09:00 UTCJun 13, 17:15 UTC8h 15m
2026-06-13 UAL994 PBI → ORD Jun 13, 00:25 UTCJun 13, 06:55 UTC6h 29m
2026-06-12 UAL995 BRU → EWR Jun 12, 10:14 UTCJun 12, 17:18 UTC7h 4m
2026-06-12 UAL995 BRU → EWR Jun 12, 10:10 UTCJun 12, 11:40 UTC1h 30m
2026-06-12 UAL972 - Jun 12, 02:35 UTCJun 12, 07:25 UTC4h 50m
2026-06-12 UAL972 - Jun 12, 00:30 UTCJun 12, 02:25 UTC1h 55m
2026-06-11 UAL971 FCO → ORD Jun 11, 18:45 UTCJun 11, 19:25 UTC40m
2026-06-11 UAL971 FCO → ORD Jun 11, 09:20 UTCJun 11, 16:30 UTC7h 10m
2026-06-11 UAL971 FCO → ORD Jun 11, 09:22 UTCJun 11, 18:28 UTC9h 6m
2026-06-10 UAL970 ORD → FCO Jun 10, 22:40 UTCJun 11, 06:50 UTC8h 10m
2026-06-10 UAL970 ORD → FCO Jun 10, 22:42 UTCJun 11, 06:50 UTC8h 8m
2026-06-09 UAL981 DUB → ORD Jun 9, 11:40 UTCJun 9, 20:25 UTC8h 45m
2026-06-09 UAL980 ORD → DUB Jun 9, 02:45 UTCJun 9, 09:40 UTC6h 55m
2026-06-08 UAL415 DEN → LGA Jun 8, 14:10 UTCJun 8, 23:10 UTC9h 0m
2026-06-08 UAL416 ORD → MXP Jun 8, 03:55 UTCJun 8, 11:50 UTC7h 55m
2026-06-07 UAL415 DEN → LGA Jun 7, 13:50 UTCJun 7, 22:15 UTC8h 25m
2026-06-07 UAL416 ORD → MXP Jun 7, 03:25 UTCJun 7, 11:10 UTC7h 45m
2026-06-06 UAL770 IAH → EWR Jun 6, 14:45 UTCJun 6, 23:30 UTC8h 45m
2026-06-06 UAL769 BDL → ORD Jun 6, 05:25 UTCJun 6, 12:45 UTC7h 20m
2026-06-05 UAL882 HND → ORD Jun 5, 09:10 UTCJun 5, 20:55 UTC11h 45m
2026-06-04 UAL881 ORD → HND Jun 4, 17:25 UTCJun 5, 05:20 UTC11h 55m
2026-06-04 UAL844 GRU → ORD Jun 4, 01:40 UTCJun 4, 11:30 UTC9h 50m
2026-06-03 UAL845 ORD → GRU Jun 3, 03:00 UTCJun 3, 12:15 UTC9h 15m
2026-06-03 UAL845 ORD → GRU Jun 3, 03:03 UTCJun 3, 12:11 UTC9h 8m
2026-06-02 UAL415 DEN → LGA Jun 2, 14:15 UTCJun 2, 22:40 UTC8h 25m
2026-06-02 UAL416 ORD → MXP Jun 2, 03:20 UTCJun 2, 11:50 UTC8h 30m
2026-06-01 UAL415 DEN → LGA Jun 1, 13:35 UTCJun 1, 21:55 UTC8h 20m
2026-06-01 UAL416 ORD → MXP Jun 1, 03:00 UTCJun 1, 10:55 UTC7h 55m
2026-05-31 UAL415 DEN → LGA May 31, 14:00 UTCMay 31, 22:50 UTC8h 50m
2026-05-31 UAL416 ORD → MXP May 31, 09:25 UTCMay 31, 11:35 UTC2h 10m
2026-05-31 UAL416 ORD → MXP May 31, 03:13 UTCMay 31, 11:31 UTC8h 18m
2026-05-30 UAL415 DEN → LGA May 30, 21:50 UTCMay 30, 21:55 UTC5m
2026-05-30 UAL415 DEN → LGA May 30, 13:42 UTCMay 30, 21:35 UTC7h 53m
2026-05-30 UAL415 DEN → LGA May 30, 13:35 UTCMay 30, 21:55 UTC8h 20m
2026-05-30 UAL416 ORD → MXP May 30, 05:15 UTCMay 30, 11:10 UTC5h 55m
2026-05-30 UAL416 ORD → MXP May 30, 03:05 UTCMay 30, 05:10 UTC2h 5m
2026-05-29 UAL971 FCO → ORD May 29, 08:20 UTCMay 29, 08:30 UTC10m
2026-05-29 UAL971 FCO → ORD May 29, 08:12 UTCMay 29, 17:36 UTC9h 24m
2026-05-28 UAL970 ORD → FCO May 28, 21:10 UTCMay 29, 05:45 UTC8h 35m
2026-05-28 UAL970 ORD → FCO May 28, 21:22 UTCMay 29, 05:42 UTC8h 20m
2026-05-26 UAL423 YYZ → DEN May 26, 20:50 UTCMay 26, 21:00 UTC10m

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 N12021 page for operator, model, and routing details .

Mode-S A0566A frequently asked

What is Mode-S code A0566A?
A0566A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N12021.
Where is Mode-S A0566A registered?
Mode-S code A0566A 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 A0566A broadcasting right now?
Yes. Mode-S A0566A is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A0566A, octal 50053152, decimal 10,507,882.
What flights does A0566A operate?
Mode-S A0566A has broadcast 20 distinct callsigns, including UAL971, UAL423, UAL416, UAL415, UAL970.