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 Jul 26, 18:50 UTC
Flights observed
268
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 18:50 UTC

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
UAL941 United Airlines 15 2026-07-24
UAL938 - 15 2026-07-08
UAL15 United Airlines 15 2026-07-22
UAL12 - 15 2026-07-01
UAL3 United Airlines 13 2026-06-30
UAL17 - 12 2026-07-11
UAL146 United Airlines 11 2026-07-22
UAL940 United Airlines 10 2026-07-24
UAL928 United Airlines 10 2026-07-07
UAL16 United Airlines 10 2026-07-25
UAL909 United Airlines 9 2026-05-06
UAL908 United Airlines 9 2026-05-06
UAL962 - 8 2026-07-14
UAL929 - 8 2026-07-01
UAL920 United Airlines 8 2026-05-22
UAL904 - 8 2026-07-09
UAL966 United Airlines 7 2026-07-23
UAL963 - 7 2026-07-15
UAL958 - 7 2026-06-30
UAL957 - 7 2026-07-12

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL921 LHR → EWR Jul 26, 17:30 UTCJul 26, 18:50 UTC1h 20m
2026-07-25 UAL16 EWR → LHR Jul 25, 21:50 UTCJul 26, 04:15 UTC6h 25m
2026-07-24 UAL941 LHR → EWR Jul 24, 15:30 UTCJul 24, 21:15 UTC5h 45m
2026-07-24 UAL941 LHR → EWR Jul 24, 15:19 UTCJul 24, 22:38 UTC7h 19m
2026-07-24 UAL940 EWR → LHR Jul 24, 04:10 UTCJul 24, 10:15 UTC6h 5m
2026-07-23 UAL967 NAP → EWR Jul 23, 12:30 UTCJul 23, 21:15 UTC8h 45m
2026-07-23 UAL967 NAP → EWR Jul 23, 12:24 UTCJul 23, 21:35 UTC9h 11m
2026-07-23 UAL966 EWR → NAP Jul 23, 06:25 UTCJul 23, 09:30 UTC3h 5m
2026-07-23 UAL966 EWR → NAP Jul 23, 01:30 UTCJul 23, 02:50 UTC1h 20m
2026-07-22 UAL15 LHR → EWR Jul 22, 15:15 UTCJul 22, 22:30 UTC7h 15m
2026-07-22 UAL146 EWR → LHR Jul 22, 03:10 UTCJul 22, 04:45 UTC1h 35m
2026-07-21 UAL15 LHR → EWR Jul 21, 15:40 UTCJul 21, 23:00 UTC7h 20m
2026-07-21 UAL146 EWR → LHR Jul 21, 06:40 UTCJul 21, 13:00 UTC6h 20m
2026-07-21 UAL967 NAP → EWR Jul 21, 02:25 UTCJul 21, 04:00 UTC1h 35m
2026-07-20 UAL967 NAP → EWR Jul 20, 19:00 UTCJul 21, 02:20 UTC7h 19m
2026-07-20 UAL967 NAP → EWR Jul 20, 18:24 UTCJul 21, 03:55 UTC9h 31m
2026-07-20 UAL966 EWR → NAP Jul 20, 14:20 UTCJul 20, 14:40 UTC20m
2026-07-20 UAL966 EWR → NAP Jul 20, 14:31 UTCJul 20, 14:45 UTC14m
2026-07-20 UAL966 EWR → NAP Jul 20, 12:00 UTCJul 20, 12:25 UTC25m
2026-07-20 UAL966 EWR → NAP Jul 20, 02:56 UTCJul 20, 11:41 UTC8h 45m
2026-07-20 UAL966 EWR → NAP Jul 20, 03:20 UTCJul 20, 12:25 UTC9h 5m
2026-07-19 UAL941 LHR → EWR Jul 19, 15:30 UTCJul 19, 22:55 UTC7h 25m
2026-07-19 UAL146 EWR → LHR Jul 19, 05:55 UTCJul 19, 12:30 UTC6h 35m
2026-07-18 UAL3932 EWR → IAD Jul 18, 12:05 UTCJul 18, 16:50 UTC4h 45m
2026-07-17 UAL965 - Jul 17, 08:15 UTCJul 17, 17:40 UTC9h 25m
2026-07-16 UAL964 EWR → NAP Jul 16, 20:53 UTCJul 17, 04:37 UTC7h 44m
2026-07-16 UAL964 EWR → NAP Jul 16, 20:45 UTCJul 17, 03:14 UTC6h 30m
2026-07-16 UAL381 - Jul 16, 08:40 UTCJul 16, 18:00 UTC9h 20m
2026-07-15 UAL380 EWR → BRI Jul 15, 20:03 UTCJul 16, 04:10 UTC8h 7m
2026-07-15 UAL380 - Jul 15, 19:45 UTCJul 15, 20:35 UTC50m
2026-07-15 UAL963 - Jul 15, 08:15 UTCJul 15, 16:20 UTC8h 5m
2026-07-14 UAL962 EWR → BER Jul 14, 21:43 UTCJul 15, 04:49 UTC7h 6m
2026-07-14 UAL962 - Jul 14, 21:20 UTCJul 14, 21:25 UTC5m
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

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 Jul 26, 18:50 UTC.
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 UAL941, UAL938, UAL15, UAL12, UAL3.