Apparatus

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sensors Mode-S transponder

A9178D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N685UA · BOEING 767-300 · operated by UNITED AIRLINES INC

Hex
A9178D
Octal
52213615
Decimal
11,081,613
Country
US
Tail
N685UA
Type
B763
No current signal · last broadcast 1d ago
Flights observed
235
Distinct callsigns
20
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A9178D.

Country allocation

The ICAO 24-bit address A9178D 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
UAL938 - 15 2026-07-08
UAL12 - 15 2026-07-01
UAL3 United Airlines 13 2026-06-30
UAL15 - 13 2026-07-08
UAL941 - 12 2026-06-16
UAL17 - 12 2026-07-11
UAL928 United Airlines 10 2026-07-07
UAL940 - 9 2026-07-07
UAL909 United Airlines 9 2026-05-06
UAL908 United Airlines 9 2026-05-06
UAL16 - 9 2026-07-10
UAL929 - 8 2026-07-01
UAL920 United Airlines 8 2026-05-22
UAL904 - 8 2026-07-09
UAL146 - 8 2026-07-06
UAL958 - 7 2026-06-30
UAL957 - 7 2026-07-12
UAL963 - 6 2026-06-28
UAL962 United Airlines 6 2026-06-27
UAL956 - 6 2026-07-12

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-12 UAL957 - Jul 12, 07:31 UTCJul 12, 15:35 UTC8h 5m
2026-07-12 UAL957 GVA → EWR Jul 12, 07:37 UTCJul 12, 15:35 UTC7h 58m
2026-07-12 UAL956 - Jul 12, 04:25 UTCJul 12, 05:30 UTC1h 5m
2026-07-11 UAL956 - Jul 11, 22:25 UTCJul 12, 04:20 UTC5h 55m
2026-07-11 UAL17 LHR → EWR Jul 11, 09:55 UTCJul 11, 17:35 UTC7h 40m
2026-07-10 UAL16 EWR → LHR Jul 10, 21:58 UTCJul 11, 04:08 UTC6h 10m
2026-07-10 UAL16 - Jul 10, 21:50 UTCJul 10, 23:25 UTC1h 35m
2026-07-09 UAL17 - Jul 9, 14:10 UTCJul 9, 21:20 UTC7h 10m
2026-07-09 UAL17 LHR → EWR Jul 9, 14:10 UTCJul 9, 21:22 UTC7h 12m
2026-07-09 UAL904 EWR → LHR Jul 9, 05:00 UTCJul 9, 11:16 UTC6h 16m
2026-07-09 UAL904 - Jul 9, 04:55 UTCJul 9, 11:15 UTC6h 20m
2026-07-08 UAL15 - Jul 8, 14:40 UTCJul 8, 21:55 UTC7h 15m
2026-07-08 UAL15 LHR → EWR Jul 8, 14:44 UTCJul 8, 21:52 UTC7h 8m
2026-07-08 UAL938 - Jul 8, 03:40 UTCJul 8, 11:10 UTC7h 30m
2026-07-07 UAL928 LHR → ORD Jul 7, 13:35 UTCJul 7, 14:50 UTC1h 15m
2026-07-07 UAL928 LHR → ORD Jul 7, 13:34 UTCJul 7, 21:36 UTC8h 2m
2026-07-07 UAL940 EWR → LHR Jul 7, 03:20 UTCJul 7, 09:40 UTC6h 20m
2026-07-06 UAL15 - Jul 6, 15:05 UTCJul 6, 16:30 UTC1h 25m
2026-07-06 UAL15 LHR → EWR Jul 6, 14:44 UTCJul 6, 22:38 UTC7h 54m
2026-07-06 UAL146 EWR → LHR Jul 6, 03:17 UTCJul 6, 09:52 UTC6h 35m
2026-07-06 UAL146 - Jul 6, 03:35 UTCJul 6, 05:05 UTC1h 30m
2026-07-05 UAL921 - Jul 5, 17:30 UTCJul 6, 00:40 UTC7h 10m
2026-07-05 UAL940 EWR → LHR Jul 5, 03:52 UTCJul 5, 10:27 UTC6h 35m
2026-07-05 UAL940 - Jul 5, 04:30 UTCJul 5, 10:40 UTC6h 10m
2026-07-04 UAL921 - Jul 4, 17:20 UTCJul 4, 18:40 UTC1h 20m
2026-07-04 UAL921 LHR → EWR Jul 4, 17:22 UTCJul 5, 00:47 UTC7h 25m
2026-07-02 UAL16 EWR → LHR Jul 2, 21:58 UTCJul 3, 04:47 UTC6h 49m
2026-07-02 UAL16 - Jul 2, 22:35 UTCJul 3, 04:50 UTC6h 15m
2026-07-02 UAL17 - Jul 2, 09:40 UTCJul 2, 15:15 UTC5h 35m
2026-07-02 UAL17 LHR → EWR Jul 2, 09:40 UTCJul 2, 17:25 UTC7h 45m
2026-07-01 UAL929 ORD → LHR Jul 1, 22:03 UTCJul 2, 05:25 UTC7h 22m
2026-07-01 UAL929 ORD → LHR Jul 1, 22:00 UTCJul 2, 05:25 UTC7h 25m
2026-07-01 UAL12 ZRH → ORD Jul 1, 08:25 UTCJul 1, 17:55 UTC9h 30m
2026-06-30 UAL3 LAX → HNL Jun 30, 21:32 UTCJul 1, 05:13 UTC7h 41m
2026-06-30 UAL3 LAX → HNL Jun 30, 21:15 UTCJul 1, 05:15 UTC8h 0m
2026-06-30 UAL958 - Jun 30, 07:20 UTCJun 30, 15:30 UTC8h 10m
2026-06-29 UAL934 EWR → LHR Jun 29, 13:12 UTCJun 29, 19:16 UTC6h 4m
2026-06-29 UAL934 EWR → LHR Jun 29, 13:04 UTCJun 29, 14:44 UTC1h 40m
2026-06-28 UAL963 BER → EWR Jun 28, 08:05 UTCJun 28, 16:19 UTC8h 15m
2026-06-27 UAL962 EWR → BER Jun 27, 21:43 UTCJun 28, 05:15 UTC7h 32m
2026-06-27 UAL962 EWR → BER Jun 27, 21:55 UTCJun 28, 05:24 UTC7h 30m
2026-06-27 UAL957 GVA → EWR Jun 27, 10:45 UTCJun 27, 17:09 UTC6h 25m
2026-06-27 UAL957 GVA → EWR Jun 27, 10:37 UTCJun 27, 18:40 UTC8h 3m
2026-06-27 UAL957 GVA → EWR Jun 27, 10:37 UTCJun 27, 18:40 UTC8h 3m
2026-06-27 UAL956 EWR → GVA Jun 27, 01:49 UTCJun 27, 08:55 UTC7h 5m
2026-06-26 UAL17 - Jun 26, 09:39 UTCJun 26, 17:00 UTC7h 20m
2026-06-25 UAL929 ORD → LHR Jun 25, 22:04 UTCJun 26, 05:35 UTC7h 30m
2026-06-25 UAL12 ZRH → ORD Jun 25, 08:19 UTCJun 25, 17:38 UTC9h 19m
2026-06-25 UAL12 - Jun 25, 08:30 UTCJun 25, 09:14 UTC45m
2026-06-24 UAL134 EWR → ZRH Jun 24, 22:55 UTCJun 25, 05:55 UTC7h 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 N685UA page for operator, model, and routing details .

Mode-S A9178D frequently asked

What is Mode-S code A9178D?
A9178D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N685UA.
Where is Mode-S A9178D registered?
Mode-S code A9178D 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 A9178D broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A9178D, octal 52213615, decimal 11,081,613.
What flights does A9178D operate?
Mode-S A9178D has broadcast 20 distinct callsigns, including UAL938, UAL12, UAL3, UAL15, UAL941.