sensors Mode-S transponder

A4BF70

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N405CK · BOEING 737-400 · operated by KALITTA CHARTERS II LLC

Hex
A4BF70
Octal
51137560
Decimal
10,796,912
Country
US
Tail
N405CK
Type
B734
Broadcasting now · callsign KII405 · 37,025 ft
Flights observed
6
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Current position

A4BF70 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A4BF70 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
KII405 - 6 2026-04-13

Recent flights last 6

DateFlightRouteTakeoffLandingDuration
2026-04-13 KII405 - Apr 13, 12:20 UTCApr 13, 14:05 UTC1h 45m
2026-04-13 KII405 - Apr 13, 11:55 UTCApr 13, 14:05 UTC2h 10m
2026-04-13 KII405 - Apr 13, 10:05 UTCApr 13, 12:15 UTC2h 10m
2026-04-13 KII405 - Apr 13, 07:55 UTCApr 13, 08:25 UTC30m
2026-04-13 KII405 - Apr 13, 04:20 UTCApr 13, 08:15 UTC3h 55m
2026-04-13 KII405 - Apr 13, 00:20 UTCApr 13, 02:50 UTC2h 30m

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 N405CK page for operator, model, and routing details .

Mode-S A4BF70 frequently asked

What is Mode-S code A4BF70?
A4BF70 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N405CK.
Where is Mode-S A4BF70 registered?
Mode-S code A4BF70 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 A4BF70 broadcasting right now?
Yes. Mode-S A4BF70 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A4BF70, octal 51137560, decimal 10,796,912.
What flights does A4BF70 operate?
Mode-S A4BF70 has broadcast 1 distinct callsign, including KII405.