Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A51D6F

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N429DX · operated by DELTA AIR LINES INC

Hex
A51D6F
Octal
51216557
Decimal
10,820,975
Country
US
Tail
N429DX
Type
A339
No current signal · last broadcast Jul 26, 21:25 UTC
Flights observed
302
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:25 UTC

Last known position

Most recent position reported by Mode-S A51D6F.

Country allocation

The ICAO 24-bit address A51D6F 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 20 distinct

Callsign Airline Flights Last seen
DAL145 Delta Air Lines 13 2026-07-21
DAL164 Delta Air Lines 11 2026-07-21
DAL3 - 10 2026-06-25
DAL9 - 9 2026-06-25
DAL81 Delta Air Lines 9 2026-07-22
DAL21 Delta Air Lines 9 2026-07-23
DAL80 Delta Air Lines 8 2026-07-22
DAL20 Delta Air Lines 8 2026-07-23
DAL165 Delta Air Lines 8 2026-07-26
DAL49 Delta Air Lines 7 2026-06-18
DAL213 - 7 2026-07-11
DAL144 Delta Air Lines 7 2026-07-26
DAL142 Delta Air Lines 7 2026-07-02
DAL137 - 6 2026-07-13
DAL136 - 6 2026-07-14
DAL57 - 5 2026-06-30
DAL4 Delta Air Lines 5 2026-04-23
DAL257 - 5 2026-06-16
DAL237 - 5 2026-07-12
DAL236 - 5 2026-07-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 DAL165 AMS → MSP Jul 26, 12:55 UTCJul 26, 21:20 UTC8h 25m
2026-07-26 DAL144 SEA → AMS Jul 26, 01:00 UTCJul 26, 09:40 UTC8h 41m
2026-07-25 DAL43 LAX → SYD Jul 25, 11:00 UTCJul 25, 22:05 UTC11h 5m
2026-07-25 DAL43 LAX → SYD Jul 25, 10:55 UTCJul 25, 22:05 UTC11h 10m
2026-07-24 DAL42 SYD → LAX Jul 24, 21:25 UTCJul 25, 07:48 UTC10h 23m
2026-07-24 DAL42 SYD → LAX Jul 24, 21:25 UTCJul 24, 21:45 UTC20m
2026-07-23 DAL21 LHR → SEA Jul 23, 17:40 UTCJul 23, 19:05 UTC1h 25m
2026-07-23 DAL21 LHR → SEA Jul 23, 17:37 UTCJul 24, 02:51 UTC9h 14m
2026-07-23 DAL21 LHR → SEA Jul 23, 17:37 UTCJul 24, 02:56 UTC9h 19m
2026-07-23 DAL20 SEA → LHR Jul 23, 05:05 UTCJul 23, 14:05 UTC9h 0m
2026-07-22 DAL81 CDG → SEA Jul 22, 14:30 UTCJul 23, 00:55 UTC10h 25m
2026-07-22 DAL81 CDG → SEA Jul 22, 14:27 UTCJul 23, 00:55 UTC10h 28m
2026-07-22 DAL80 SEA → CDG Jul 22, 02:00 UTCJul 22, 10:25 UTC8h 25m
2026-07-21 DAL145 AMS → SEA Jul 21, 13:33 UTCJul 21, 23:22 UTC9h 49m
2026-07-21 DAL145 AMS → SEA Jul 21, 13:35 UTCJul 21, 19:45 UTC6h 10m
2026-07-21 DAL164 MSP → AMS Jul 21, 03:10 UTCJul 21, 10:45 UTC7h 35m
2026-07-20 DAL165 AMS → MSP Jul 20, 14:10 UTCJul 20, 15:30 UTC1h 20m
2026-07-20 DAL165 AMS → MSP Jul 20, 14:07 UTCJul 20, 22:19 UTC8h 12m
2026-07-20 DAL165 AMS → MSP Jul 20, 14:07 UTCJul 20, 22:23 UTC8h 16m
2026-07-20 DAL144 SEA → AMS Jul 20, 01:38 UTCJul 20, 10:49 UTC9h 11m
2026-07-20 DAL144 SEA → AMS Jul 20, 01:40 UTCJul 20, 03:30 UTC1h 50m
2026-07-19 DAL249 TLV → ATL Jul 19, 12:10 UTCJul 19, 23:05 UTC10h 55m
2026-07-18 DAL248 SEA → BCN Jul 18, 22:48 UTCJul 19, 08:51 UTC10h 3m
2026-07-18 DAL248 - Jul 18, 22:50 UTCJul 19, 00:35 UTC1h 45m
2026-07-17 DAL21 LHR → SEA Jul 17, 17:09 UTCJul 18, 02:35 UTC9h 25m
2026-07-17 DAL21 LHR → SEA Jul 17, 17:07 UTCJul 18, 02:34 UTC9h 27m
2026-07-17 DAL20 SEA → LHR Jul 17, 05:25 UTCJul 17, 14:20 UTC8h 55m
2026-07-16 DAL21 LHR → SEA Jul 16, 17:10 UTCJul 17, 02:34 UTC9h 25m
2026-07-16 DAL20 SEA → LHR Jul 16, 05:21 UTCJul 16, 14:13 UTC8h 52m
2026-07-16 DAL20 - Jul 16, 05:25 UTCJul 16, 07:10 UTC1h 45m
2026-07-15 DAL81 - Jul 15, 14:55 UTCJul 15, 20:10 UTC5h 15m
2026-07-15 DAL81 CDG → SEA Jul 15, 14:54 UTCJul 16, 00:44 UTC9h 50m
2026-07-15 DAL81 CDG → SEA Jul 15, 14:54 UTCJul 16, 00:51 UTC9h 57m
2026-07-15 DAL80 SEA → CDG Jul 15, 02:45 UTCJul 15, 12:05 UTC9h 20m
2026-07-14 DAL145 AMS → SEA Jul 14, 13:48 UTCJul 14, 23:29 UTC9h 41m
2026-07-14 DAL145 - Jul 14, 13:50 UTCJul 14, 23:35 UTC9h 44m
2026-07-14 DAL136 - Jul 14, 02:45 UTCJul 14, 03:45 UTC1h 0m
2026-07-14 DAL136 DTW → AMS Jul 14, 02:45 UTCJul 14, 10:22 UTC7h 37m
2026-07-13 DAL137 - Jul 13, 19:50 UTCJul 13, 21:25 UTC1h 35m
2026-07-13 DAL137 - Jul 13, 13:45 UTCJul 13, 19:40 UTC5h 55m
2026-07-13 DAL236 TPA → AMS Jul 13, 02:30 UTCJul 13, 11:25 UTC8h 55m
2026-07-12 DAL237 - Jul 12, 13:15 UTCJul 12, 13:45 UTC30m
2026-07-12 DAL237 AMS → TPA Jul 12, 13:15 UTCJul 12, 22:24 UTC9h 9m
2026-07-12 DAL48 JFK → AMS Jul 12, 03:26 UTCJul 12, 10:08 UTC6h 42m
2026-07-12 DAL48 JFK → AMS Jul 12, 03:25 UTCJul 12, 10:05 UTC6h 40m
2026-07-11 DAL213 ATH → JFK Jul 11, 13:15 UTCJul 11, 23:25 UTC10h 10m
2026-07-11 DAL212 JFK → ATH Jul 11, 01:32 UTCJul 11, 10:36 UTC9h 4m
2026-07-11 DAL212 - Jul 11, 01:35 UTCJul 11, 03:10 UTC1h 35m
2026-07-10 DAL157 ACC → JFK Jul 10, 12:39 UTCJul 10, 22:24 UTC9h 45m
2026-07-10 DAL156 - Jul 10, 00:50 UTCJul 10, 08:25 UTC7h 35m

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 N429DX page for operator, model, and routing details .

Mode-S A51D6F frequently asked

What is Mode-S code A51D6F?
A51D6F is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N429DX.
Where is Mode-S A51D6F registered?
Mode-S code A51D6F 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 A51D6F broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:25 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A51D6F, octal 51216557, decimal 10,820,975.
What flights does A51D6F operate?
Mode-S A51D6F has broadcast 20 distinct callsigns, including DAL145, DAL164, DAL3, DAL9, DAL81.