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 Jul 25, 21:25 UTC
Flights observed
259
Distinct callsigns
20
Country
US
Last broadcast
Jul 25, 21:25 UTC

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 14 2026-07-19
UAL46 - 13 2026-06-25
UAL507 United Airlines 11 2026-07-19
UAL852 United Airlines 10 2026-07-24
UAL47 - 9 2026-06-26
UAL853 United Airlines 8 2026-07-23
UAL18 - 8 2026-07-03
UAL14 - 8 2026-07-07
UAL984 - 7 2026-04-13
UAL5 - 7 2026-06-24
UAL19 - 7 2026-07-03
UAL160 United Airlines 7 2026-07-25
UAL59 United Airlines 6 2026-05-13
UAL194 United Airlines 6 2026-07-24
UAL905 - 5 2026-07-08
UAL889 - 5 2026-07-21
UAL888 - 5 2026-07-20
UAL818 - 5 2026-06-28
UAL71 - 5 2026-07-14
UAL56 United Airlines 5 2026-07-07

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-25 UAL160 MUC → IAH Jul 25, 10:40 UTCJul 25, 21:25 UTC10h 45m
2026-07-24 UAL194 SFO → MUC Jul 24, 21:38 UTCJul 25, 08:12 UTC10h 34m
2026-07-24 UAL194 SFO → MUC Jul 24, 21:55 UTCJul 25, 08:00 UTC10h 5m
2026-07-24 UAL852 TPE → SAN Jul 24, 08:05 UTCJul 24, 09:25 UTC1h 20m
2026-07-24 UAL852 TPE → SAN Jul 24, 06:40 UTCJul 24, 06:50 UTC10m
2026-07-24 UAL852 TPE → SAN Jul 24, 06:51 UTCJul 24, 18:21 UTC11h 30m
2026-07-23 UAL853 SFO → TPE Jul 23, 19:20 UTCJul 23, 19:35 UTC15m
2026-07-23 UAL853 SFO → TPE Jul 23, 07:35 UTCJul 23, 18:00 UTC10h 25m
2026-07-22 UAL673 SFO → BOS Jul 22, 14:30 UTCJul 23, 02:00 UTC11h 30m
2026-07-22 UAL672 EWR → ATL Jul 22, 01:10 UTCJul 22, 11:50 UTC10h 40m
2026-07-21 UAL889 - Jul 21, 11:00 UTCJul 21, 21:25 UTC10h 25m
2026-07-20 UAL888 SFO → PEK Jul 20, 18:15 UTCJul 21, 06:34 UTC12h 19m
2026-07-20 UAL888 - Jul 20, 18:10 UTCJul 20, 18:40 UTC30m
2026-07-19 UAL506 MSN → DEN Jul 19, 14:10 UTCJul 20, 02:35 UTC12h 25m
2026-07-19 UAL507 DEN → LGA Jul 19, 00:30 UTCJul 19, 11:20 UTC10h 50m
2026-07-18 UAL916 - Jul 18, 12:50 UTCJul 18, 13:35 UTC45m
2026-07-18 UAL916 - Jul 18, 02:05 UTCJul 18, 02:35 UTC30m
2026-07-17 UAL917 SFO → AKL Jul 17, 07:30 UTCJul 17, 19:55 UTC12h 25m
2026-07-17 UAL917 SFO → AKL Jul 17, 06:31 UTCJul 17, 19:38 UTC13h 7m
2026-07-16 UAL45 ZRH → SFO Jul 16, 12:12 UTCJul 16, 23:51 UTC11h 39m
2026-07-16 UAL45 ZRH → SFO Jul 16, 12:12 UTCJul 16, 23:53 UTC11h 41m
2026-07-16 UAL45 - Jul 16, 12:14 UTCJul 16, 13:30 UTC1h 15m
2026-07-15 UAL44 SFO → ZRH Jul 15, 21:48 UTCJul 16, 08:14 UTC10h 26m
2026-07-15 UAL44 - Jul 15, 21:55 UTCJul 16, 00:10 UTC2h 15m
2026-07-15 UAL3041 EWR → SFO Jul 15, 13:42 UTCJul 15, 18:25 UTC4h 43m
2026-07-15 UAL3041 EWR → SFO Jul 15, 13:40 UTCJul 15, 18:35 UTC4h 55m
2026-07-14 UAL71 AMS → EWR Jul 14, 07:27 UTCJul 14, 14:30 UTC7h 3m
2026-07-14 UAL71 - Jul 14, 07:35 UTCJul 14, 14:35 UTC7h 0m
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

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 Jul 25, 21:25 UTC.
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, UAL852, UAL47.