Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A12AC1

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N17421 · BOEING 737 MAX 9 · operated by UNITED AIRLINES INC

Hex
A12AC1
Octal
50225301
Decimal
10,562,241
Country
US
Tail
N17421
Type
B39M
No current signal · last broadcast Jul 26, 21:45 UTC
Flights observed
434
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Last known position

Most recent position reported by Mode-S A12AC1.

Country allocation

The ICAO 24-bit address A12AC1 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
UAL1372 United Airlines 6 2026-04-18
UAL1289 United Airlines 6 2026-06-17
UAL1043 - 6 2026-06-24
UAL1321 United Airlines 5 2026-07-19
UAL8202 United Airlines 4 2026-04-13
UAL731 - 4 2026-07-19
UAL2661 - 4 2026-07-15
UAL2608 United Airlines 4 2026-05-14
UAL240 United Airlines 4 2026-06-24
UAL2219 - 4 2026-07-09
UAL2066 United Airlines 4 2026-04-13
UAL1904 - 4 2026-07-08
UAL1739 United Airlines 4 2026-06-14
UAL1147 - 4 2026-04-17
UAL785 United Airlines 3 2026-04-27
UAL738 United Airlines 3 2026-05-07
UAL727 United Airlines 3 2026-05-26
UAL689 - 3 2026-06-19
UAL3924 United Airlines 3 2026-04-16
UAL339 United Airlines 3 2026-06-15

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2339 LAS → LAX Jul 26, 20:20 UTCJul 26, 21:45 UTC1h 25m
2026-07-26 UAL1318 EWR → MSY Jul 26, 17:15 UTCJul 26, 18:45 UTC1h 30m
2026-07-26 UAL257 EWR → PBI Jul 26, 11:00 UTCJul 26, 15:10 UTC4h 10m
2026-07-25 UAL256 IAH → BON Jul 25, 17:40 UTCJul 25, 21:40 UTC4h 0m
2026-07-25 UAL1467 DEN → EWR Jul 25, 12:25 UTCJul 25, 14:50 UTC2h 25m
2026-07-25 UAL1266 LAX → SAL Jul 25, 06:10 UTCJul 25, 10:40 UTC4h 30m
2026-07-25 UAL1103 DEN → BOS Jul 25, 01:35 UTCJul 25, 02:15 UTC40m
2026-07-24 UAL1103 DEN → BOS Jul 24, 21:20 UTCJul 24, 21:30 UTC10m
2026-07-24 UAL1798 - Jul 24, 14:20 UTCJul 24, 19:35 UTC5h 15m
2026-07-24 UAL413 MCO → EWR Jul 24, 00:25 UTCJul 24, 05:00 UTC4h 35m
2026-07-23 UAL413 MCO → EWR Jul 23, 21:00 UTCJul 23, 23:10 UTC2h 10m
2026-07-23 UAL2071 SNA → EWR Jul 23, 14:30 UTCJul 23, 19:20 UTC4h 50m
2026-07-23 UAL1603 ORD → PHX Jul 23, 02:05 UTCJul 23, 03:25 UTC1h 20m
2026-07-22 UAL1168 BZN → SFO Jul 22, 19:10 UTCJul 23, 00:10 UTC5h 0m
2026-07-22 UAL2120 MFE → IAH Jul 22, 14:55 UTCJul 22, 17:45 UTC2h 50m
2026-07-22 UAL1267 EWR → ANC Jul 22, 03:30 UTCJul 22, 13:05 UTC9h 35m
2026-07-21 UAL8120 YHZ → BOS Jul 21, 22:00 UTCJul 22, 01:35 UTC3h 35m
2026-07-21 UAL2449 SJC → IAH Jul 21, 17:10 UTCJul 21, 18:45 UTC1h 35m
2026-07-21 UAL233 DEN → SFO Jul 21, 05:40 UTCJul 21, 07:15 UTC1h 35m
2026-07-21 UAL2681 DEN → SFO Jul 21, 03:35 UTCJul 21, 04:35 UTC1h 0m
2026-07-20 UAL3049 ORD → SFO Jul 20, 22:30 UTCJul 20, 23:10 UTC40m
2026-07-20 UAL3049 ORD → SFO Jul 20, 18:05 UTCJul 20, 18:15 UTC10m
2026-07-20 UAL1723 SBA → SFO Jul 20, 05:05 UTCJul 20, 05:20 UTC15m
2026-07-20 UAL1723 SBA → SFO Jul 20, 00:25 UTCJul 20, 01:05 UTC40m
2026-07-19 UAL1321 MIA → EWR Jul 19, 21:05 UTCJul 19, 21:55 UTC50m
2026-07-19 UAL1321 MIA → EWR Jul 19, 17:10 UTCJul 19, 17:30 UTC20m
2026-07-19 UAL731 - Jul 19, 08:30 UTCJul 19, 08:40 UTC10m
2026-07-19 UAL731 - Jul 19, 03:45 UTCJul 19, 04:40 UTC55m
2026-07-18 UAL2862 SFO → DEN Jul 18, 21:20 UTCJul 19, 02:25 UTC5h 5m
2026-07-18 UAL2081 - Jul 18, 13:20 UTCJul 18, 18:05 UTC4h 45m
2026-07-18 UAL1971 EWR → SAT Jul 18, 00:50 UTCJul 18, 01:30 UTC40m
2026-07-17 UAL1267 - Jul 17, 22:20 UTCJul 17, 23:14 UTC55m
2026-07-17 UAL8106 - Jul 17, 19:30 UTCJul 17, 20:29 UTC1h 0m
2026-07-17 UAL1540 - Jul 17, 12:25 UTCJul 17, 17:35 UTC5h 10m
2026-07-17 UAL1230 SFO → FLL Jul 17, 04:49 UTCJul 17, 10:00 UTC5h 10m
2026-07-16 UAL1799 LAS → SFO Jul 16, 22:40 UTCJul 16, 23:44 UTC1h 5m
2026-07-16 UAL611 - Jul 16, 19:05 UTCJul 16, 20:15 UTC1h 10m
2026-07-16 UAL2192 - Jul 16, 12:40 UTCJul 16, 17:25 UTC4h 45m
2026-07-16 UAL1646 DEN → BWI Jul 16, 00:35 UTCJul 16, 03:40 UTC3h 5m
2026-07-15 UAL1263 - Jul 15, 20:40 UTCJul 15, 22:40 UTC2h 0m
2026-07-15 UAL2661 - Jul 15, 18:05 UTCJul 15, 19:05 UTC1h 0m
2026-07-15 UAL2441 - Jul 15, 10:20 UTCJul 15, 15:50 UTC5h 30m
2026-07-14 UAL2001 SFO → BOS Jul 14, 23:45 UTCJul 15, 04:55 UTC5h 10m
2026-07-14 UAL1321 - Jul 14, 20:55 UTCJul 14, 21:40 UTC45m
2026-07-14 UAL1321 KOA → SFO Jul 14, 17:17 UTCJul 14, 21:35 UTC4h 18m
2026-07-14 UAL1321 - Jul 14, 17:00 UTCJul 14, 17:10 UTC10m
2026-07-14 UAL731 - Jul 14, 07:05 UTCJul 14, 07:25 UTC20m
2026-07-14 UAL731 - Jul 14, 02:25 UTCJul 14, 02:55 UTC30m
2026-07-13 UAL2862 IAD → SFO Jul 13, 20:00 UTCJul 14, 00:45 UTC4h 45m
2026-07-13 UAL2057 SAV → IAD Jul 13, 16:18 UTCJul 13, 17:21 UTC1h 3m

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 N17421 page for operator, model, and routing details .

Mode-S A12AC1 frequently asked

What is Mode-S code A12AC1?
A12AC1 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N17421.
Where is Mode-S A12AC1 registered?
Mode-S code A12AC1 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 A12AC1 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A12AC1, octal 50225301, decimal 10,562,241.
What flights does A12AC1 operate?
Mode-S A12AC1 has broadcast 20 distinct callsigns, including UAL1372, UAL1289, UAL1043, UAL1321, UAL8202.