Apparatus

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sensors Mode-S transponder

AD5621

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N959AL · AIRBUS HELICOPTERS EC-135/635 · operated by AIR METHODS LLC

Hex
AD5621
Octal
53253041
Decimal
11,359,777
Country
US
Tail
N959AL
Type
EC35
No current signal · last broadcast 12d ago
Flights observed
377
Distinct callsigns
1
Country
US
Last broadcast
12d ago

Last known position

Most recent position reported by Mode-S AD5621.

Country allocation

The ICAO 24-bit address AD5621 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
ALFT - 377 2026-07-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 ALFT - Jul 26, 09:35 UTCJul 26, 10:00 UTC25m
2026-07-26 ALFT - Jul 26, 08:00 UTCJul 26, 08:50 UTC50m
2026-07-26 ALFT - Jul 26, 06:25 UTCJul 26, 06:35 UTC11m
2026-07-26 ALFT - Jul 26, 05:05 UTCJul 26, 05:55 UTC50m
2026-07-26 ALFT - Jul 26, 02:20 UTCJul 26, 02:30 UTC10m
2026-07-26 ALFT - Jul 26, 01:40 UTCJul 26, 01:50 UTC10m
2026-07-25 ALFT - Jul 25, 14:45 UTCJul 25, 15:10 UTC25m
2026-07-25 ALFT - Jul 25, 14:00 UTCJul 25, 14:15 UTC15m
2026-07-25 ALFT - Jul 25, 09:00 UTCJul 25, 10:05 UTC1h 5m
2026-07-25 ALFT - Jul 25, 07:45 UTCJul 25, 08:10 UTC25m
2026-07-25 ALFT - Jul 25, 06:05 UTCJul 25, 06:20 UTC15m
2026-07-25 ALFT - Jul 25, 01:20 UTCJul 25, 02:00 UTC40m
2026-07-24 ALFT - Jul 24, 02:55 UTCJul 24, 03:10 UTC15m
2026-07-23 ALFT - Jul 23, 17:50 UTCJul 23, 18:15 UTC25m
2026-07-23 ALFT - Jul 23, 16:50 UTCJul 23, 17:00 UTC10m
2026-07-22 ALFT - Jul 22, 02:35 UTCJul 22, 03:00 UTC25m
2026-07-22 ALFT - Jul 22, 01:15 UTCJul 22, 01:30 UTC15m
2026-07-20 ALFT - Jul 20, 20:25 UTCJul 20, 20:45 UTC20m
2026-07-20 ALFT - Jul 20, 19:00 UTCJul 20, 19:25 UTC25m
2026-07-20 ALFT - Jul 20, 05:45 UTCJul 20, 05:55 UTC10m
2026-07-20 ALFT - Jul 20, 04:35 UTCJul 20, 04:45 UTC10m
2026-07-20 ALFT - Jul 20, 03:20 UTCJul 20, 03:35 UTC15m
2026-07-20 ALFT - Jul 20, 02:35 UTCJul 20, 02:50 UTC15m
2026-07-20 ALFT - Jul 20, 02:00 UTCJul 20, 02:20 UTC20m
2026-07-19 ALFT - Jul 19, 20:55 UTCJul 19, 21:05 UTC10m
2026-07-19 ALFT - Jul 19, 19:55 UTCJul 19, 20:25 UTC30m
2026-07-19 ALFT - Jul 19, 18:55 UTCJul 19, 19:15 UTC20m
2026-07-19 ALFT - Jul 19, 18:15 UTCJul 19, 18:45 UTC30m
2026-07-19 ALFT - Jul 19, 17:30 UTCJul 19, 17:55 UTC25m
2026-07-19 ALFT - Jul 19, 16:35 UTCJul 19, 16:55 UTC20m
2026-07-19 ALFT - Jul 19, 09:15 UTCJul 19, 10:05 UTC50m
2026-07-19 ALFT - Jul 19, 08:10 UTCJul 19, 08:25 UTC15m
2026-07-19 ALFT - Jul 19, 06:55 UTCJul 19, 07:25 UTC30m
2026-07-19 ALFT - Jul 19, 05:05 UTCJul 19, 06:00 UTC55m
2026-07-18 ALFT - Jul 18, 23:55 UTCJul 19, 00:10 UTC15m
2026-07-18 ALFT - Jul 18, 23:10 UTCJul 18, 23:25 UTC15m
2026-07-18 ALFT - Jul 18, 16:05 UTCJul 18, 16:30 UTC25m
2026-07-18 ALFT - Jul 18, 15:25 UTCJul 18, 15:45 UTC20m
2026-07-18 ALFT - Jul 18, 12:35 UTCJul 18, 13:30 UTC55m
2026-07-18 ALFT - Jul 18, 03:00 UTCJul 18, 04:20 UTC1h 20m
2026-07-17 ALFT - Jul 17, 22:15 UTCJul 17, 22:40 UTC25m
2026-07-17 ALFT - Jul 17, 20:50 UTCJul 17, 21:34 UTC45m
2026-07-17 ALFT - Jul 17, 05:55 UTCJul 17, 06:10 UTC15m
2026-07-17 ALFT - Jul 17, 04:59 UTCJul 17, 05:15 UTC15m
2026-07-16 ALFT - Jul 16, 06:10 UTCJul 16, 06:35 UTC25m
2026-07-16 ALFT - Jul 16, 04:35 UTCJul 16, 05:15 UTC40m
2026-07-16 ALFT - Jul 16, 00:50 UTCJul 16, 01:15 UTC25m
2026-07-15 ALFT - Jul 15, 22:05 UTCJul 15, 23:10 UTC1h 5m
2026-07-15 ALFT - Jul 15, 20:30 UTCJul 15, 21:05 UTC35m
2026-07-15 ALFT - Jul 15, 08:20 UTCJul 15, 09:10 UTC50m

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 N959AL page for operator, model, and routing details .

Mode-S AD5621 frequently asked

What is Mode-S code AD5621?
AD5621 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N959AL.
Where is Mode-S AD5621 registered?
Mode-S code AD5621 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 AD5621 broadcasting right now?
No active broadcast right now. Last signal was 12d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AD5621, octal 53253041, decimal 11,359,777.
What flights does AD5621 operate?
Mode-S AD5621 has broadcast 1 distinct callsign, including ALFT.