Apparatus

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sensors Mode-S transponder

A1D546

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N217UA · BOEING 777-200 · operated by UNITED AIRLINES INC

Hex
A1D546
Octal
50352506
Decimal
10,605,894
Country
US
Tail
N217UA
Type
B772
No current signal · last broadcast 1h ago
Flights observed
231
Distinct callsigns
20
Country
US
Last broadcast
1h ago

Last known position

Most recent position reported by Mode-S A1D546.

Country allocation

The ICAO 24-bit address A1D546 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
UAL506 United Airlines 13 2026-06-01
UAL46 - 13 2026-06-25
UAL507 United Airlines 10 2026-06-01
UAL47 - 9 2026-06-26
UAL18 - 8 2026-07-03
UAL14 - 8 2026-07-07
UAL984 - 7 2026-04-13
UAL852 United Airlines 7 2026-05-12
UAL5 - 7 2026-06-24
UAL19 - 7 2026-07-03
UAL853 United Airlines 6 2026-05-11
UAL59 United Airlines 6 2026-05-13
UAL160 United Airlines 6 2026-05-18
UAL905 - 5 2026-07-08
UAL818 - 5 2026-06-28
UAL56 United Airlines 5 2026-07-07
UAL41 United Airlines 5 2026-04-30
UAL915 - 4 2026-07-07
UAL889 United Airlines 4 2026-05-07
UAL819 - 4 2026-06-27

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 UAL70 - Jul 13, 22:20 UTCJul 14, 05:00 UTC6h 40m
2026-07-13 UAL22 DUB → EWR Jul 13, 09:45 UTCJul 13, 16:10 UTC6h 25m
2026-07-13 UAL23 EWR → DUB Jul 13, 01:25 UTCJul 13, 07:15 UTC5h 50m
2026-07-12 UAL71 - Jul 12, 07:25 UTCJul 12, 14:40 UTC7h 15m
2026-07-11 UAL70 EWR → AMS Jul 11, 22:40 UTCJul 12, 05:01 UTC6h 20m
2026-07-11 UAL55 - Jul 11, 11:25 UTCJul 11, 18:55 UTC7h 30m
2026-07-11 UAL55 CDG → EWR Jul 11, 11:34 UTCJul 11, 18:57 UTC7h 23m
2026-07-11 UAL54 - Jul 11, 02:10 UTCJul 11, 08:40 UTC6h 30m
2026-07-09 UAL22 DUB → EWR Jul 9, 08:45 UTCJul 9, 15:15 UTC6h 30m
2026-07-09 UAL22 DUB → EWR Jul 9, 08:50 UTCJul 9, 15:25 UTC6h 35m
2026-07-09 UAL23 EWR → DUB Jul 9, 00:15 UTCJul 9, 06:08 UTC5h 53m
2026-07-09 UAL23 EWR → DUB Jul 9, 00:25 UTCJul 9, 06:20 UTC5h 55m
2026-07-08 UAL905 - Jul 8, 08:55 UTCJul 8, 15:55 UTC7h 0m
2026-07-07 UAL14 EWR → LHR Jul 7, 23:35 UTCJul 8, 05:52 UTC6h 17m
2026-07-07 UAL14 EWR → LHR Jul 7, 23:35 UTCJul 8, 05:55 UTC6h 20m
2026-07-07 UAL56 CDG → EWR Jul 7, 09:40 UTCJul 7, 16:55 UTC7h 15m
2026-07-07 UAL56 CDG → EWR Jul 7, 09:44 UTCJul 7, 16:58 UTC7h 14m
2026-07-07 UAL915 IAD → CDG Jul 7, 00:20 UTCJul 7, 07:15 UTC6h 55m
2026-07-06 UAL915 IAD → CDG Jul 6, 23:11 UTCJul 7, 07:09 UTC7h 58m
2026-07-05 UAL925 LHR → IAD Jul 5, 22:15 UTCJul 6, 05:45 UTC7h 30m
2026-07-05 UAL925 LHR → IAD Jul 5, 22:24 UTCJul 6, 05:41 UTC7h 17m
2026-07-05 UAL918D IAD → LHR Jul 5, 14:10 UTCJul 5, 20:30 UTC6h 20m
2026-07-05 UAL918 IAD → IAD Jul 5, 01:45 UTCJul 5, 06:00 UTC4h 15m
2026-07-04 UAL919 - Jul 4, 11:30 UTCJul 4, 19:10 UTC7h 40m
2026-07-04 UAL14 EWR → LHR Jul 4, 00:20 UTCJul 4, 07:41 UTC7h 21m
2026-07-04 UAL14 EWR → LHR Jul 4, 01:20 UTCJul 4, 07:50 UTC6h 30m
2026-07-03 UAL18 MXP → EWR Jul 3, 09:30 UTCJul 3, 17:30 UTC8h 0m
2026-07-03 UAL19 - Jul 3, 00:30 UTCJul 3, 07:25 UTC6h 55m
2026-07-02 UAL71 AMS → EWR Jul 2, 07:35 UTCJul 2, 15:05 UTC7h 30m
2026-07-02 UAL71 AMS → EWR Jul 2, 07:27 UTCJul 2, 15:00 UTC7h 33m
2026-07-01 UAL70 EWR → AMS Jul 1, 22:40 UTCJul 2, 04:55 UTC6h 15m
2026-07-01 UAL905 - Jul 1, 09:05 UTCJul 1, 10:20 UTC1h 15m
2026-07-01 UAL905 LHR → EWR Jul 1, 08:55 UTCJul 1, 16:21 UTC7h 26m
2026-06-30 UAL14 - Jun 30, 23:25 UTCJul 1, 05:55 UTC6h 30m
2026-06-30 UAL18 MXP → EWR Jun 30, 09:20 UTCJun 30, 17:20 UTC8h 0m
2026-06-30 UAL19 EWR → MXP Jun 30, 00:18 UTCJun 30, 06:51 UTC6h 33m
2026-06-30 UAL19 EWR → MXP Jun 30, 00:00 UTCJun 30, 06:55 UTC6h 56m
2026-06-29 UAL905 - Jun 29, 09:00 UTCJun 29, 10:20 UTC1h 20m
2026-06-29 UAL905 LHR → EWR Jun 29, 08:55 UTCJun 29, 16:06 UTC7h 11m
2026-06-28 UAL880 IAH → LHR Jun 28, 21:45 UTCJun 29, 06:29 UTC8h 45m
2026-06-28 UAL818 - Jun 28, 00:04 UTCJun 28, 09:50 UTC9h 45m
2026-06-27 UAL819 - Jun 27, 02:04 UTCJun 27, 11:30 UTC9h 25m
2026-06-26 UAL47 - Jun 26, 12:39 UTCJun 26, 22:49 UTC10h 10m
2026-06-25 UAL46 - Jun 25, 23:44 UTCJun 26, 08:50 UTC9h 5m
2026-06-24 UAL4 - Jun 24, 13:10 UTCJun 24, 22:29 UTC9h 20m
2026-06-24 UAL4 LHR → IAH Jun 24, 13:05 UTCJun 24, 22:25 UTC9h 20m
2026-06-24 UAL5 - Jun 24, 01:49 UTCJun 24, 10:19 UTC8h 30m
2026-06-23 UAL47 - Jun 23, 12:20 UTCJun 23, 22:29 UTC10h 10m
2026-06-22 UAL46 - Jun 22, 23:45 UTCJun 23, 08:45 UTC9h 0m
2026-06-21 UAL47 - Jun 21, 13:09 UTCJun 21, 13:29 UTC20m

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 N217UA page for operator, model, and routing details .

Mode-S A1D546 frequently asked

What is Mode-S code A1D546?
A1D546 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N217UA.
Where is Mode-S A1D546 registered?
Mode-S code A1D546 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 A1D546 broadcasting right now?
No active broadcast right now. Last signal was 1h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1D546, octal 50352506, decimal 10,605,894.
What flights does A1D546 operate?
Mode-S A1D546 has broadcast 20 distinct callsigns, including UAL506, UAL46, UAL507, UAL47, UAL18.