sensors Mode-S transponder

A6F9B3

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N549DN · AIRBUS A-321neo · operated by DELTA AIR LINES INC

Hex
A6F9B3
Octal
51574663
Decimal
10,942,899
Country
US
Tail
N549DN
Type
A21N
No current signal · last broadcast 1d ago
Flights observed
9
Distinct callsigns
3
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A6F9B3.

Country allocation

The ICAO 24-bit address A6F9B3 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 3 distinct

Callsign Airline Flights Last seen
DAL795 Delta Air Lines 6 2026-04-13
DAL671 - 2 2026-04-13
DAL917 - 1 2026-04-12

Recent flights last 9

DateFlightRouteTakeoffLandingDuration
2026-04-13 DAL795 BOS → ORD Apr 13, 19:50 UTCApr 13, 23:25 UTC3h 35m
2026-04-13 DAL795 BOS → ORD Apr 13, 19:00 UTCApr 13, 20:10 UTC1h 10m
2026-04-13 DAL795 BOS → ORD Apr 13, 16:15 UTCApr 13, 17:10 UTC55m
2026-04-13 DAL795 BOS → ORD Apr 13, 15:50 UTCApr 13, 17:10 UTC1h 20m
2026-04-13 DAL795 BOS → ORD Apr 13, 12:20 UTCApr 13, 16:15 UTC3h 55m
2026-04-13 DAL795 BOS → ORD Apr 13, 11:55 UTCApr 13, 12:15 UTC20m
2026-04-13 DAL671 - Apr 13, 00:20 UTCApr 13, 00:40 UTC20m
2026-04-12 DAL671 - Apr 12, 23:55 UTCApr 13, 00:40 UTC45m
2026-04-12 DAL917 - Apr 12, 17:15 UTCApr 12, 18:35 UTC1h 20m

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 N549DN page for operator, model, and routing details .

Mode-S A6F9B3 frequently asked

What is Mode-S code A6F9B3?
A6F9B3 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N549DN.
Where is Mode-S A6F9B3 registered?
Mode-S code A6F9B3 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 A6F9B3 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 A6F9B3, octal 51574663, decimal 10,942,899.
What flights does A6F9B3 operate?
Mode-S A6F9B3 has broadcast 3 distinct callsigns, including DAL795, DAL671, DAL917.