sensors Mode-S transponder

A21D70

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N2350E · CESSNA 172 Skyhawk · operated by MELBOURNE FLIGHT TRAINING LLC

Hex
A21D70
Octal
50416560
Decimal
10,624,368
Country
US
Tail
N2350E
Type
C172
No current signal · last broadcast 23h ago
Flights observed
5
Distinct callsigns
1
Country
US
Last broadcast
23h ago

Last known position

Most recent position reported by Mode-S A21D70.

Country allocation

The ICAO 24-bit address A21D70 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
N2350E - 5 2026-04-13

Recent flights last 5

DateFlightRouteTakeoffLandingDuration
2026-04-13 N2350E - Apr 13, 22:35 UTCApr 13, 23:40 UTC1h 5m
2026-04-13 N2350E - Apr 13, 15:50 UTCApr 13, 16:20 UTC30m
2026-04-13 N2350E - Apr 13, 15:00 UTCApr 13, 16:15 UTC1h 15m
2026-04-12 N2350E - Apr 12, 20:00 UTCApr 12, 20:15 UTC15m
2026-04-12 N2350E MLB → MLB Apr 12, 17:35 UTCApr 12, 18:15 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 N2350E page for operator, model, and routing details .

Mode-S A21D70 frequently asked

What is Mode-S code A21D70?
A21D70 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N2350E.
Where is Mode-S A21D70 registered?
Mode-S code A21D70 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 A21D70 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 A21D70, octal 50416560, decimal 10,624,368.
What flights does A21D70 operate?
Mode-S A21D70 has broadcast 1 distinct callsign, including N2350E.