sensors Mode-S transponder

A12AC3

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N17423 · BOEING 737 MAX 9 · operated by UNITED AIRLINES INC

Hex
A12AC3
Octal
50225303
Decimal
10,562,243
Country
US
Tail
N17423
Type
B39M
No current signal · last broadcast 23h ago
Flights observed
11
Distinct callsigns
5
Country
US
Last broadcast
23h ago

Last known position

Most recent position reported by Mode-S A12AC3.

Country allocation

The ICAO 24-bit address A12AC3 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 5 distinct

Callsign Airline Flights Last seen
UAL360 United Airlines 4 2026-04-13
UAL2210 United Airlines 3 2026-04-13
UAL2658 United Airlines 2 2026-04-13
UAL2086 United Airlines 1 2026-04-12
UAL1591 United Airlines 1 2026-04-13

Recent flights last 11

DateFlightRouteTakeoffLandingDuration
2026-04-13 UAL1591 DEN → EWR Apr 13, 20:50 UTCApr 13, 23:30 UTC2h 40m
2026-04-13 UAL360 DFW → EWR Apr 13, 16:15 UTCApr 13, 18:55 UTC2h 40m
2026-04-13 UAL360 DFW → EWR Apr 13, 15:50 UTCApr 13, 18:55 UTC3h 5m
2026-04-13 UAL360 DFW → EWR Apr 13, 12:45 UTCApr 13, 16:15 UTC3h 30m
2026-04-13 UAL2210 SAN → IAH Apr 13, 08:20 UTCApr 13, 10:55 UTC2h 35m
2026-04-13 UAL2210 SAN → IAH Apr 13, 07:55 UTCApr 13, 10:55 UTC3h 0m
2026-04-13 UAL2210 SAN → IAH Apr 13, 06:00 UTCApr 13, 11:17 UTC5h 17m
2026-04-13 UAL2658 IAH → MCO Apr 13, 03:55 UTCApr 13, 04:20 UTC25m
2026-04-13 UAL2658 IAH → MCO Apr 13, 00:51 UTCApr 13, 04:17 UTC3h 26m
2026-04-12 UAL2086 EWR → ATL Apr 12, 19:26 UTCApr 12, 22:17 UTC2h 51m
2026-04-12 UAL360 DFW → EWR Apr 12, 17:15 UTCApr 12, 17:55 UTC40m

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 N17423 page for operator, model, and routing details .

Mode-S A12AC3 frequently asked

What is Mode-S code A12AC3?
A12AC3 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N17423.
Where is Mode-S A12AC3 registered?
Mode-S code A12AC3 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 A12AC3 broadcasting right now?
No active broadcast right now. Last signal was 23h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A12AC3, octal 50225303, decimal 10,562,243.
What flights does A12AC3 operate?
Mode-S A12AC3 has broadcast 5 distinct callsigns, including UAL360, UAL2210, UAL2658, UAL2086, UAL1591.