sensors Mode-S transponder

A3A509

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N334DU · operated by DELTA AIR LINES INC

Hex
A3A509
Octal
50722411
Decimal
10,724,617
Country
US
Tail
N334DU
Type
BCS3
Broadcasting now · callsign DAL2549 · 27,000 ft
Flights observed
11
Distinct callsigns
5
Country
US
Last broadcast
1d ago

Current position

A3A509 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A3A509 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 5 distinct

Callsign Airline Flights Last seen
DAL483 - 4 2026-04-13
DAL1354 Delta Air Lines 3 2026-04-13
DAL541 - 2 2026-04-13
DAL498 Delta Air Lines 1 2026-04-13
DAL2508 - 1 2026-04-12

Recent flights last 11

DateFlightRouteTakeoffLandingDuration
2026-04-13 DAL498 DTW → CHS Apr 13, 21:50 UTCApr 13, 23:45 UTC1h 55m
2026-04-13 DAL483 - Apr 13, 19:50 UTCApr 13, 20:15 UTC25m
2026-04-13 DAL483 - Apr 13, 16:15 UTCApr 13, 20:10 UTC3h 55m
2026-04-13 DAL483 - Apr 13, 15:50 UTCApr 13, 19:45 UTC3h 55m
2026-04-13 DAL483 - Apr 13, 15:34 UTCApr 13, 20:02 UTC4h 28m
2026-04-13 DAL1354 IAD → ATL Apr 13, 12:20 UTCApr 13, 12:40 UTC20m
2026-04-13 DAL1354 IAD → ATL Apr 13, 11:55 UTCApr 13, 12:40 UTC45m
2026-04-13 DAL1354 IAD → ATL Apr 13, 11:25 UTCApr 13, 12:15 UTC50m
2026-04-13 DAL541 - Apr 13, 00:40 UTCApr 13, 03:45 UTC3h 5m
2026-04-12 DAL541 - Apr 12, 23:55 UTCApr 13, 03:45 UTC3h 50m
2026-04-12 DAL2508 - Apr 12, 18:38 UTCApr 12, 21:04 UTC2h 26m

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 N334DU page for operator, model, and routing details .

Mode-S A3A509 frequently asked

What is Mode-S code A3A509?
A3A509 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N334DU.
Where is Mode-S A3A509 registered?
Mode-S code A3A509 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 A3A509 broadcasting right now?
Yes. Mode-S A3A509 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A3A509, octal 50722411, decimal 10,724,617.
What flights does A3A509 operate?
Mode-S A3A509 has broadcast 5 distinct callsigns, including DAL483, DAL1354, DAL541, DAL498, DAL2508.