sensors Mode-S transponder

A6B21D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N530TG · operated by HELICOPTERS UNLIMITED LLC

Hex
A6B21D
Octal
51531035
Decimal
10,924,573
Country
US
Tail
N530TG
Type
H500
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 A6B21D.

Country allocation

The ICAO 24-bit address A6B21D 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
N530TG - 5 2026-04-13

Recent flights last 5

DateFlightRouteTakeoffLandingDuration
2026-04-13 N530TG - Apr 13, 20:05 UTCApr 13, 22:05 UTC2h 0m
2026-04-13 N530TG - Apr 13, 18:00 UTCApr 13, 19:15 UTC1h 15m
2026-04-13 N530TG - Apr 13, 16:15 UTCApr 13, 17:15 UTC1h 0m
2026-04-13 N530TG - Apr 13, 15:50 UTCApr 13, 16:15 UTC25m
2026-04-13 N530TG - Apr 13, 13:45 UTCApr 13, 14:00 UTC15m

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 N530TG page for operator, model, and routing details .

Mode-S A6B21D frequently asked

What is Mode-S code A6B21D?
A6B21D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N530TG.
Where is Mode-S A6B21D registered?
Mode-S code A6B21D 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 A6B21D 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 A6B21D, octal 51531035, decimal 10,924,573.
What flights does A6B21D operate?
Mode-S A6B21D has broadcast 1 distinct callsign, including N530TG.