Apparatus

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sensors Mode-S transponder

3E1681

ICAO 24-bit transponder address · allocated to Germany

Currently assigned to D-HZSJ · AIRBUS HELICOPTERS EC-135/635

Hex
3E1681
Octal
17413201
Decimal
4,068,993
Country
DE
Tail
D-HZSJ
Type
EC35
No current signal · last broadcast 13h ago
Flights observed
10
Distinct callsigns
1
Country
DE
Last broadcast
13h ago

Last known position

Most recent position reported by Mode-S 3E1681.

Country allocation

The ICAO 24-bit address 3E1681 falls within the block assigned to Germany (DE) by ICAO Annex 10, Volume III. Every aircraft registered in Germany 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
CHX35 - 10 2026-04-14

Recent flights last 10

DateFlightRouteTakeoffLandingDuration
2026-04-14 CHX35 - Apr 14, 09:20 UTCApr 14, 09:25 UTC5m
2026-04-14 CHX35 - Apr 14, 08:50 UTCApr 14, 09:00 UTC10m
2026-04-14 CHX35 - Apr 14, 07:25 UTCApr 14, 07:35 UTC10m
2026-04-14 CHX35 - Apr 14, 06:45 UTCApr 14, 06:55 UTC10m
2026-04-13 CHX35 - Apr 13, 17:05 UTCApr 13, 17:35 UTC30m
2026-04-13 CHX35 - Apr 13, 16:10 UTCApr 13, 16:20 UTC10m
2026-04-13 CHX35 - Apr 13, 10:55 UTCApr 13, 11:00 UTC5m
2026-04-13 CHX35 - Apr 13, 08:20 UTCApr 13, 08:30 UTC10m
2026-04-13 CHX35 - Apr 13, 08:00 UTCApr 13, 08:15 UTC15m
2026-04-12 CHX35 - Apr 12, 17:15 UTCApr 12, 17:35 UTC20m

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 D-HZSJ page for operator, model, and routing details .

Mode-S 3E1681 frequently asked

What is Mode-S code 3E1681?
3E1681 is an ICAO 24-bit transponder address. Allocated to Germany. Assigned to D-HZSJ.
Where is Mode-S 3E1681 registered?
Mode-S code 3E1681 is allocated to Germany (DE). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 3E1681 broadcasting right now?
No active broadcast right now. Last signal was 13h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 3E1681, octal 17413201, decimal 4,068,993.
What flights does 3E1681 operate?
Mode-S 3E1681 has broadcast 1 distinct callsign, including CHX35.