Apparatus

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sensors Mode-S transponder

A875DA

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N644UA · BOEING 767-300 · operated by UNITED AIRLINES INC

Hex
A875DA
Octal
52072732
Decimal
11,040,218
Country
US
Tail
N644UA
Type
B763
No current signal · last broadcast Jul 26, 22:30 UTC
Flights observed
220
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:30 UTC

Last known position

Most recent position reported by Mode-S A875DA.

Country allocation

The ICAO 24-bit address A875DA 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
UAL946 United Airlines 18 2026-07-23
UAL331 - 15 2026-07-12
UAL21 United Airlines 15 2026-07-24
UAL947 United Airlines 14 2026-07-22
UAL330 - 14 2026-07-12
UAL321 United Airlines 14 2026-07-22
UAL20 United Airlines 14 2026-07-26
UAL129 United Airlines 14 2026-07-25
UAL128 United Airlines 11 2026-07-26
UAL322 United Airlines 10 2026-07-23
UAL855 United Airlines 8 2026-07-21
UAL749 - 8 2026-07-14
UAL854 United Airlines 7 2026-07-20
UAL748 - 7 2026-07-13
UAL53 - 7 2026-06-22
UAL52 - 7 2026-06-21
UAL242 - 6 2026-07-08
UAL243 - 5 2026-07-08
UAL126 - 5 2026-06-24
UAL925 United Airlines 4 2026-05-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL20 IAH → AMS Jul 26, 21:35 UTCJul 26, 22:30 UTC55m
2026-07-26 UAL128 GIG → IAH Jul 26, 02:35 UTCJul 26, 12:40 UTC10h 6m
2026-07-25 UAL129 IAH → GIG Jul 25, 01:45 UTCJul 25, 11:25 UTC9h 40m
2026-07-24 UAL21 AMS → IAH Jul 24, 09:15 UTCJul 24, 19:25 UTC10h 10m
2026-07-23 UAL946 IAD → AMS Jul 23, 22:03 UTCJul 24, 05:01 UTC6h 58m
2026-07-23 UAL946 IAD → AMS Jul 23, 22:30 UTCJul 24, 04:30 UTC6h 0m
2026-07-23 UAL322 BOI → DEN Jul 23, 07:55 UTCJul 23, 17:25 UTC9h 30m
2026-07-22 UAL321 ATL → EWR Jul 22, 21:50 UTCJul 23, 05:40 UTC7h 50m
2026-07-22 UAL947 AMS → IAD Jul 22, 11:20 UTCJul 22, 17:50 UTC6h 30m
2026-07-21 UAL20 IAH → AMS Jul 21, 21:45 UTCJul 22, 00:40 UTC2h 55m
2026-07-21 UAL20 IAH → AMS Jul 21, 21:47 UTCJul 22, 07:15 UTC9h 28m
2026-07-21 UAL855 LIM → IAH Jul 21, 06:45 UTCJul 21, 12:35 UTC5h 50m
2026-07-20 UAL854 IAH → LIM Jul 20, 21:35 UTCJul 21, 03:15 UTC5h 40m
2026-07-20 UAL128 GIG → IAH Jul 20, 01:30 UTCJul 20, 10:35 UTC9h 5m
2026-07-20 UAL128 GIG → IAH Jul 20, 00:30 UTCJul 20, 00:45 UTC15m
2026-07-19 UAL129 IAH → GIG Jul 19, 01:35 UTCJul 19, 11:20 UTC9h 45m
2026-07-18 UAL21 - Jul 18, 10:15 UTCJul 18, 20:25 UTC10h 10m
2026-07-17 UAL946 IAD → AMS Jul 17, 22:05 UTCJul 18, 05:30 UTC7h 26m
2026-07-17 UAL947 - Jul 17, 09:35 UTCJul 17, 17:35 UTC8h 0m
2026-07-16 UAL20 - Jul 16, 22:10 UTCJul 17, 07:30 UTC9h 20m
2026-07-15 UAL21 - Jul 15, 09:30 UTCJul 15, 19:35 UTC10h 5m
2026-07-14 UAL946 IAD → AMS Jul 14, 22:05 UTCJul 15, 05:20 UTC7h 14m
2026-07-14 UAL749 - Jul 14, 09:00 UTCJul 14, 11:10 UTC2h 10m
2026-07-14 UAL749 GVA → IAD Jul 14, 09:12 UTCJul 14, 17:21 UTC8h 9m
2026-07-13 UAL748 IAD → GVA Jul 13, 21:43 UTCJul 14, 05:13 UTC7h 30m
2026-07-13 UAL748 - Jul 13, 21:35 UTCJul 14, 04:30 UTC6h 55m
2026-07-12 UAL331 - Jul 12, 15:25 UTCJul 12, 23:15 UTC7h 50m
2026-07-12 UAL330 - Jul 12, 05:50 UTCJul 12, 12:50 UTC7h 0m
2026-07-11 UAL331 - Jul 11, 15:20 UTCJul 11, 23:35 UTC8h 15m
2026-07-11 UAL330 IAD → CDG Jul 11, 03:05 UTCJul 11, 10:15 UTC7h 10m
2026-07-10 UAL322 - Jul 10, 10:10 UTCJul 10, 10:30 UTC20m
2026-07-10 UAL322 VCE → IAD Jul 10, 10:04 UTCJul 10, 19:16 UTC9h 12m
2026-07-09 UAL321 - Jul 9, 23:15 UTCJul 10, 01:25 UTC2h 10m
2026-07-09 UAL321 IAD → VCE Jul 9, 22:43 UTCJul 10, 07:23 UTC8h 40m
2026-07-09 UAL749 - Jul 9, 09:25 UTCJul 9, 18:20 UTC8h 55m
2026-07-09 UAL749 GVA → IAD Jul 9, 09:17 UTCJul 9, 18:03 UTC8h 46m
2026-07-08 UAL748 IAD → GVA Jul 8, 22:40 UTCJul 9, 06:15 UTC7h 35m
2026-07-08 UAL243 NCE → IAD Jul 8, 08:24 UTCJul 8, 16:51 UTC8h 27m
2026-07-08 UAL243 NCE → IAD Jul 8, 08:10 UTCJul 8, 16:50 UTC8h 40m
2026-07-08 UAL242 - Jul 8, 06:05 UTCJul 8, 06:15 UTC10m
2026-07-07 UAL242 IAD → NCE Jul 7, 22:15 UTCJul 8, 06:00 UTC7h 45m
2026-07-07 UAL749 - Jul 7, 09:20 UTCJul 7, 17:50 UTC8h 30m
2026-07-06 UAL748 - Jul 6, 22:45 UTCJul 7, 06:30 UTC7h 45m
2026-07-06 UAL748 IAD → GVA Jul 6, 22:03 UTCJul 7, 06:30 UTC8h 27m
2026-07-06 UAL243 - Jul 6, 08:20 UTCJul 6, 17:25 UTC9h 5m
2026-07-05 UAL242 IAD → NCE Jul 5, 21:45 UTCJul 6, 05:30 UTC7h 45m
2026-07-05 UAL322 - Jul 5, 08:10 UTCJul 5, 11:10 UTC3h 0m
2026-07-05 UAL322 VCE → IAD Jul 5, 08:19 UTCJul 5, 17:33 UTC9h 14m
2026-07-04 UAL321 IAD → VCE Jul 4, 21:40 UTCJul 5, 05:25 UTC7h 45m
2026-07-04 UAL322 - Jul 4, 07:55 UTCJul 4, 17:20 UTC9h 25m

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 N644UA page for operator, model, and routing details .

Mode-S A875DA frequently asked

What is Mode-S code A875DA?
A875DA is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N644UA.
Where is Mode-S A875DA registered?
Mode-S code A875DA 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 A875DA broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:30 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A875DA, octal 52072732, decimal 11,040,218.
What flights does A875DA operate?
Mode-S A875DA has broadcast 20 distinct callsigns, including UAL946, UAL331, UAL21, UAL947, UAL330.