sensors Mode-S transponder

A3C21A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N341MB · operated by AMERICAN AIRLINES INC

Hex
A3C21A
Octal
50741032
Decimal
10,732,058
Country
US
Tail
N341MB
No current signal · last broadcast 1d ago
Flights observed
17
Distinct callsigns
9
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A3C21A.

Country allocation

The ICAO 24-bit address A3C21A 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 9 distinct

Callsign Airline Flights Last seen
ENY3542 - 4 2026-04-13
ENY4106 Envoy Air 3 2026-04-13
ENY4030 - 2 2026-04-13
ENY3805 - 2 2026-04-13
ENY3708 - 2 2026-04-13
ENY4245 - 1 2026-04-12
ENY4014 - 1 2026-04-12
ENY3431 - 1 2026-04-13
ENY3364 - 1 2026-04-13

Recent flights last 17

DateFlightRouteTakeoffLandingDuration
2026-04-13 ENY3364 - Apr 13, 21:55 UTCApr 13, 23:10 UTC1h 15m
2026-04-13 ENY3708 - Apr 13, 19:50 UTCApr 13, 20:10 UTC20m
2026-04-13 ENY3708 - Apr 13, 18:45 UTCApr 13, 20:10 UTC1h 25m
2026-04-13 ENY4106 ORD → BOS Apr 13, 16:15 UTCApr 13, 17:25 UTC1h 10m
2026-04-13 ENY4106 ORD → BOS Apr 13, 16:05 UTCApr 13, 16:15 UTC10m
2026-04-13 ENY4106 ORD → BOS Apr 13, 13:30 UTCApr 13, 15:00 UTC1h 30m
2026-04-13 ENY4030 - Apr 13, 11:16 UTCApr 13, 12:07 UTC51m
2026-04-13 ENY4030 - Apr 13, 11:07 UTCApr 13, 11:46 UTC39m
2026-04-13 ENY3431 - Apr 13, 05:50 UTCApr 13, 06:45 UTC55m
2026-04-13 ENY3542 - Apr 13, 04:20 UTCApr 13, 04:30 UTC10m
2026-04-13 ENY3542 - Apr 13, 03:55 UTCApr 13, 04:30 UTC35m
2026-04-13 ENY3542 - Apr 13, 03:00 UTCApr 13, 04:25 UTC1h 25m
2026-04-13 ENY3542 - Apr 13, 01:20 UTCApr 13, 02:31 UTC1h 11m
2026-04-13 ENY3805 - Apr 13, 00:07 UTCApr 13, 01:08 UTC1h 1m
2026-04-13 ENY3805 CRP → DFW Apr 13, 00:50 UTCApr 13, 01:00 UTC10m
2026-04-12 ENY4245 - Apr 12, 19:55 UTCApr 12, 20:10 UTC15m
2026-04-12 ENY4014 - Apr 12, 17:15 UTCApr 12, 19:05 UTC1h 50m

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 N341MB page for operator, model, and routing details .

Mode-S A3C21A frequently asked

What is Mode-S code A3C21A?
A3C21A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N341MB.
Where is Mode-S A3C21A registered?
Mode-S code A3C21A 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 A3C21A 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 A3C21A, octal 50741032, decimal 10,732,058.
What flights does A3C21A operate?
Mode-S A3C21A has broadcast 9 distinct callsigns, including ENY3542, ENY4106, ENY4030, ENY3805, ENY3708.