sensors Mode-S transponder

A39D9B

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N332DU · operated by DELTA AIR LINES INC

Hex
A39D9B
Octal
50716633
Decimal
10,722,715
Country
US
Tail
N332DU
Type
BCS3
Broadcasting now · callsign DAL922 · 37,000 ft
Flights observed
9
Distinct callsigns
3
Country
US
Last broadcast
23h ago

Current position

A39D9B is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A39D9B 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
DAL2140 - 6 2026-04-13
DAL716 Delta Air Lines 2 2026-04-13
DAL710 - 1 2026-04-13

Recent flights last 9

DateFlightRouteTakeoffLandingDuration
2026-04-13 DAL710 - Apr 13, 23:20 UTCApr 13, 23:45 UTC25m
2026-04-13 DAL2140 - Apr 13, 19:50 UTCApr 13, 21:50 UTC2h 0m
2026-04-13 DAL2140 - Apr 13, 18:50 UTCApr 13, 19:45 UTC55m
2026-04-13 DAL2140 - Apr 13, 18:46 UTCApr 13, 21:46 UTC3h 0m
2026-04-13 DAL2140 - Apr 13, 16:15 UTCApr 13, 17:10 UTC55m
2026-04-13 DAL2140 - Apr 13, 15:50 UTCApr 13, 17:10 UTC1h 20m
2026-04-13 DAL2140 - Apr 13, 13:52 UTCApr 13, 17:09 UTC3h 17m
2026-04-13 DAL716 BOS → ATL Apr 13, 00:30 UTCApr 13, 03:35 UTC3h 5m
2026-04-12 DAL716 BOS → ATL Apr 12, 18:35 UTCApr 12, 20:15 UTC1h 40m

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 N332DU page for operator, model, and routing details .

Mode-S A39D9B frequently asked

What is Mode-S code A39D9B?
A39D9B is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N332DU.
Where is Mode-S A39D9B registered?
Mode-S code A39D9B 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 A39D9B broadcasting right now?
Yes. Mode-S A39D9B is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A39D9B, octal 50716633, decimal 10,722,715.
What flights does A39D9B operate?
Mode-S A39D9B has broadcast 3 distinct callsigns, including DAL2140, DAL716, DAL710.