sensors Mode-S transponder

ACF4E8

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N934DZ · operated by DELTA AIR LINES INC

Hex
ACF4E8
Octal
53172350
Decimal
11,334,888
Country
US
Tail
N934DZ
Type
B739
Broadcasting now · callsign DAL1651 · 38,000 ft
Flights observed
10
Distinct callsigns
4
Country
US
Last broadcast
23h ago

Current position

ACF4E8 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address ACF4E8 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 4 distinct

Callsign Airline Flights Last seen
DAL2323 Delta Air Lines 4 2026-04-13
DAL2475 - 3 2026-04-13
DAL1514 Delta Air Lines 2 2026-04-12
DAL1636 - 1 2026-04-13

Recent flights last 10

DateFlightRouteTakeoffLandingDuration
2026-04-13 DAL2323 BOS → JAX Apr 13, 21:11 UTCApr 14, 00:38 UTC3h 27m
2026-04-13 DAL2323 BOS → JAX Apr 13, 16:15 UTCApr 13, 19:10 UTC2h 55m
2026-04-13 DAL2323 BOS → JAX Apr 13, 15:50 UTCApr 13, 19:10 UTC3h 20m
2026-04-13 DAL2323 BOS → JAX Apr 13, 15:42 UTCApr 13, 19:31 UTC3h 49m
2026-04-13 DAL2475 - Apr 13, 12:20 UTCApr 13, 13:50 UTC1h 30m
2026-04-13 DAL2475 - Apr 13, 11:55 UTCApr 13, 13:50 UTC1h 55m
2026-04-13 DAL2475 - Apr 13, 11:33 UTCApr 13, 13:46 UTC2h 13m
2026-04-13 DAL1636 - Apr 13, 00:35 UTCApr 13, 02:55 UTC2h 20m
2026-04-12 DAL1514 JFK → PBI Apr 12, 19:45 UTCApr 12, 20:15 UTC30m
2026-04-12 DAL1514 JFK → PBI Apr 12, 17:15 UTCApr 12, 17:40 UTC25m

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 N934DZ page for operator, model, and routing details .

Mode-S ACF4E8 frequently asked

What is Mode-S code ACF4E8?
ACF4E8 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N934DZ.
Where is Mode-S ACF4E8 registered?
Mode-S code ACF4E8 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 ACF4E8 broadcasting right now?
Yes. Mode-S ACF4E8 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex ACF4E8, octal 53172350, decimal 11,334,888.
What flights does ACF4E8 operate?
Mode-S ACF4E8 has broadcast 4 distinct callsigns, including DAL2323, DAL2475, DAL1514, DAL1636.