sensors Mode-S transponder

A54EFC

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N441GT · CESSNA 680 Citation Sovereign · operated by GAT II INC

Hex
A54EFC
Octal
51247374
Decimal
10,833,660
Country
US
Tail
N441GT
Type
C680
No current signal · last broadcast 1d ago
Flights observed
5
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A54EFC.

Country allocation

The ICAO 24-bit address A54EFC 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 1 distinct

Callsign Airline Flights Last seen
N441GT - 5 2026-04-13

Recent flights last 5

DateFlightRouteTakeoffLandingDuration
2026-04-13 N441GT - Apr 13, 16:15 UTCApr 13, 19:15 UTC3h 0m
2026-04-13 N441GT - Apr 13, 15:50 UTCApr 13, 19:15 UTC3h 25m
2026-04-13 N441GT - Apr 13, 14:45 UTCApr 13, 16:15 UTC1h 30m
2026-04-13 N441GT - Apr 13, 00:25 UTCApr 13, 02:05 UTC1h 40m
2026-04-12 N441GT - Apr 12, 23:55 UTCApr 13, 00:00 UTC5m

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 N441GT page for operator, model, and routing details .

Mode-S A54EFC frequently asked

What is Mode-S code A54EFC?
A54EFC is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N441GT.
Where is Mode-S A54EFC registered?
Mode-S code A54EFC 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 A54EFC broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A54EFC, octal 51247374, decimal 10,833,660.
What flights does A54EFC operate?
Mode-S A54EFC has broadcast 1 distinct callsign, including N441GT.