sensors Mode-S transponder

A9FA04

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N742AM · BOEING 787-9 Dreamliner · operated by UMB BANK NA TRUSTEE

Hex
A9FA04
Octal
52375004
Decimal
11,139,588
Country
US
Tail
N742AM
Type
B789
Broadcasting now · callsign AMX039 · 37,975 ft
Flights observed
6
Distinct callsigns
3
Country
US
Last broadcast
12h ago

Current position

A9FA04 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A9FA04 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 3 distinct

Callsign Airline Flights Last seen
AMX002 - 3 2026-04-13
AMX027 Aeroméxico 2 2026-04-13
AMX001 - 1 2026-04-14

Recent flights last 6

DateFlightRouteTakeoffLandingDuration
2026-04-14 AMX001 - Apr 14, 09:10 UTCApr 14, 10:20 UTC1h 10m
2026-04-13 AMX002 - Apr 13, 19:50 UTCApr 13, 20:45 UTC55m
2026-04-13 AMX002 - Apr 13, 17:30 UTCApr 13, 20:10 UTC2h 40m
2026-04-13 AMX002 - Apr 13, 09:10 UTCApr 13, 10:10 UTC1h 0m
2026-04-13 AMX027 MEX → MAD Apr 13, 01:00 UTCApr 13, 02:15 UTC1h 15m
2026-04-12 AMX027 MEX → MAD Apr 12, 18:15 UTCApr 12, 18:55 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 N742AM page for operator, model, and routing details .

Mode-S A9FA04 frequently asked

What is Mode-S code A9FA04?
A9FA04 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N742AM.
Where is Mode-S A9FA04 registered?
Mode-S code A9FA04 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 A9FA04 broadcasting right now?
Yes. Mode-S A9FA04 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A9FA04, octal 52375004, decimal 11,139,588.
What flights does A9FA04 operate?
Mode-S A9FA04 has broadcast 3 distinct callsigns, including AMX002, AMX027, AMX001.