Apparatus

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sensors Mode-S transponder

A12378

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N17233 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A12378
Octal
50221570
Decimal
10,560,376
Country
US
Tail
N17233
Type
B738
No current signal · last broadcast Jul 26, 19:10 UTC
Flights observed
447
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 19:10 UTC

Last known position

Most recent position reported by Mode-S A12378.

Country allocation

The ICAO 24-bit address A12378 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
UAL678 - 5 2026-07-17
UAL2617 United Airlines 5 2026-06-04
UAL483 - 4 2026-04-13
UAL2270 - 4 2026-07-14
UAL2064 United Airlines 4 2026-05-13
UAL1546 - 4 2026-06-25
UAL1325 - 4 2026-07-12
UAL1311 - 4 2026-06-17
UAL717 - 3 2026-07-01
UAL680 United Airlines 3 2026-04-18
UAL362 United Airlines 3 2026-07-21
UAL295 United Airlines 3 2026-07-25
UAL2748 United Airlines 3 2026-04-16
UAL2745 - 3 2026-06-17
UAL2638 - 3 2026-07-05
UAL2368 United Airlines 3 2026-06-15
UAL2257 United Airlines 3 2026-04-24
UAL2232 United Airlines 3 2026-07-20
UAL214 United Airlines 3 2026-06-05
UAL2135 - 3 2026-07-06

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2185 MSY → SFO Jul 26, 16:45 UTCJul 26, 19:10 UTC2h 25m
2026-07-26 UAL2648 SFO → LAS Jul 26, 12:15 UTCJul 26, 14:35 UTC2h 20m
2026-07-26 UAL2121 IAH → ORD Jul 26, 00:20 UTCJul 26, 02:25 UTC2h 5m
2026-07-25 UAL1255 MCI → EWR Jul 25, 20:55 UTCJul 25, 22:40 UTC1h 45m
2026-07-25 UAL295 DEN → GEG Jul 25, 17:35 UTCJul 25, 19:25 UTC1h 50m
2026-07-25 UAL644 LAX → EWR Jul 25, 14:05 UTCJul 25, 15:40 UTC1h 35m
2026-07-25 UAL1565 SFO → PHX Jul 25, 01:35 UTCJul 25, 03:00 UTC1h 25m
2026-07-24 UAL2152 SJD → DEN Jul 24, 20:32 UTCJul 24, 23:16 UTC2h 44m
2026-07-24 UAL2152 SJD → DEN Jul 24, 16:15 UTCJul 24, 23:20 UTC7h 5m
2026-07-24 UAL1241 DEN → CLE Jul 24, 12:10 UTCJul 24, 14:20 UTC2h 10m
2026-07-24 UAL1303 EWR → IAH Jul 24, 01:55 UTCJul 24, 04:10 UTC2h 15m
2026-07-23 UAL2012 PTY → EWR Jul 23, 20:30 UTCJul 24, 00:00 UTC3h 30m
2026-07-23 UAL2012 PTY → EWR Jul 23, 20:34 UTCJul 24, 00:23 UTC3h 49m
2026-07-23 UAL1362 DEN → BWI Jul 23, 16:05 UTCJul 23, 19:05 UTC3h 0m
2026-07-23 UAL1362 DEN → BWI Jul 23, 16:07 UTCJul 23, 19:05 UTC2h 58m
2026-07-23 UAL1774 ORD → EWR Jul 23, 12:10 UTCJul 23, 14:00 UTC1h 50m
2026-07-23 UAL1172 BOS → SFO Jul 23, 02:30 UTCJul 23, 04:15 UTC1h 45m
2026-07-22 UAL719 MIA → EWR Jul 22, 23:05 UTCJul 23, 01:15 UTC2h 10m
2026-07-22 UAL719 MIA → EWR Jul 22, 22:59 UTCJul 23, 01:12 UTC2h 13m
2026-07-22 UAL2808 ORF → IAH Jul 22, 18:05 UTCJul 22, 20:10 UTC2h 5m
2026-07-22 UAL2045 TPA → EWR Jul 22, 11:50 UTCJul 22, 15:25 UTC3h 35m
2026-07-21 UAL1741 MSY → EWR Jul 21, 22:20 UTCJul 22, 01:50 UTC3h 30m
2026-07-21 UAL2470 DEN → MCI Jul 21, 18:15 UTCJul 21, 20:40 UTC2h 25m
2026-07-21 UAL362 HNL → EWR Jul 21, 13:55 UTCJul 21, 16:30 UTC2h 35m
2026-07-21 UAL1924 SAN → SFO Jul 21, 01:40 UTCJul 21, 03:35 UTC1h 55m
2026-07-20 UAL2232 ORD → MSP Jul 20, 21:50 UTCJul 20, 23:50 UTC2h 0m
2026-07-20 UAL2232 ORD → MSP Jul 20, 21:59 UTCJul 20, 23:47 UTC1h 48m
2026-07-20 UAL708 - Jul 20, 18:45 UTCJul 20, 20:00 UTC1h 15m
2026-07-20 UAL2159 DCA → IAH Jul 20, 16:10 UTCJul 20, 17:15 UTC1h 5m
2026-07-20 UAL1767 DEN → DCA Jul 20, 05:00 UTCJul 20, 14:10 UTC9h 10m
2026-07-20 UAL1924 SAN → SFO Jul 20, 01:40 UTCJul 20, 03:35 UTC1h 55m
2026-07-19 UAL2232 ORD → MSP Jul 19, 22:20 UTCJul 20, 00:25 UTC2h 5m
2026-07-19 UAL708 - Jul 19, 19:05 UTCJul 19, 20:20 UTC1h 15m
2026-07-19 UAL2159 DCA → IAH Jul 19, 16:20 UTCJul 19, 17:35 UTC1h 15m
2026-07-19 UAL2433 BOS → DEN Jul 19, 04:41 UTCJul 19, 08:24 UTC3h 43m
2026-07-19 UAL2433 BOS → DEN Jul 19, 04:35 UTCJul 19, 08:25 UTC3h 50m
2026-07-18 UAL2466 ORD → BOS Jul 18, 23:00 UTCJul 19, 01:15 UTC2h 15m
2026-07-18 UAL2466 ORD → BOS Jul 18, 22:56 UTCJul 19, 01:12 UTC2h 16m
2026-07-18 UAL1215 - Jul 18, 16:25 UTCJul 18, 18:40 UTC2h 15m
2026-07-18 UAL2622 - Jul 18, 13:25 UTCJul 18, 15:05 UTC1h 40m
2026-07-18 UAL726 LAS → ORD Jul 18, 07:30 UTCJul 18, 10:45 UTC3h 15m
2026-07-18 UAL726 LAS → ORD Jul 18, 07:13 UTCJul 18, 10:33 UTC3h 20m
2026-07-18 UAL8109 ATL → YYZ Jul 18, 01:25 UTCJul 18, 03:55 UTC2h 31m
2026-07-17 UAL1794 - Jul 17, 20:25 UTCJul 17, 23:35 UTC3h 10m
2026-07-17 UAL678 - Jul 17, 15:25 UTCJul 17, 18:25 UTC3h 0m
2026-07-17 UAL678 IAH → LGA Jul 17, 15:20 UTCJul 17, 18:26 UTC3h 6m
2026-07-17 UAL575 BOS → ORD Jul 17, 11:55 UTCJul 17, 13:45 UTC1h 50m
2026-07-16 UAL2864 - Jul 16, 23:49 UTCJul 17, 01:55 UTC2h 5m
2026-07-16 UAL2864 IAH → CLT Jul 16, 23:46 UTCJul 17, 01:57 UTC2h 11m
2026-07-16 UAL1242 - Jul 16, 15:45 UTCJul 16, 21:40 UTC5h 55m

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 N17233 page for operator, model, and routing details .

Mode-S A12378 frequently asked

What is Mode-S code A12378?
A12378 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N17233.
Where is Mode-S A12378 registered?
Mode-S code A12378 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 A12378 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 19:10 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A12378, octal 50221570, decimal 10,560,376.
What flights does A12378 operate?
Mode-S A12378 has broadcast 20 distinct callsigns, including UAL678, UAL2617, UAL483, UAL2270, UAL2064.