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 1h ago
Flights observed
266
Distinct callsigns
20
Country
US
Last broadcast
1h ago

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
DAL3 - 10 2026-06-25
DAL164 - 10 2026-06-26
DAL9 - 9 2026-06-25
DAL145 - 9 2026-06-26
DAL49 Delta Air Lines 7 2026-06-18
DAL213 - 7 2026-07-11
DAL142 Delta Air Lines 7 2026-07-02
DAL80 - 6 2026-06-27
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
DAL227 - 5 2026-06-23
DAL212 - 5 2026-07-11
DAL81 Delta Air Lines 4 2026-06-27
DAL59 Delta Air Lines 4 2026-06-02
DAL58 Delta Air Lines 4 2026-06-01

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
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, 10:19 UTC7h 34m
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
2026-07-09 DAL47 AMS → JFK Jul 9, 09:15 UTCJul 9, 16:45 UTC7h 30m
2026-07-09 DAL47 AMS → JFK Jul 9, 09:15 UTCJul 9, 16:44 UTC7h 29m
2026-07-08 DAL72 - Jul 8, 22:35 UTCJul 9, 01:40 UTC3h 5m
2026-07-08 DAL72 ATL → AMS Jul 8, 22:34 UTCJul 9, 06:48 UTC8h 14m
2026-07-08 DAL2342 - Jul 8, 18:15 UTCJul 8, 20:00 UTC1h 45m
2026-07-08 DAL2342 JFK → ATL Jul 8, 18:13 UTCJul 8, 19:57 UTC1h 44m
2026-07-07 DAL213 ATH → JFK Jul 7, 14:44 UTCJul 8, 00:31 UTC9h 47m
2026-07-07 DAL213 ATH → JFK Jul 7, 14:45 UTCJul 8, 00:35 UTC9h 50m
2026-07-07 DAL212 JFK → ATH Jul 7, 01:40 UTCJul 7, 10:25 UTC8h 45m
2026-07-06 DAL1575 ATL → JFK Jul 6, 19:20 UTCJul 6, 21:10 UTC1h 50m
2026-07-06 DAL1575 ATL → JFK Jul 6, 19:25 UTCJul 6, 21:10 UTC1h 45m
2026-07-05 DAL85 - Jul 5, 15:00 UTCJul 5, 16:40 UTC1h 40m
2026-07-05 DAL85 CDG → ATL Jul 5, 14:56 UTCJul 6, 00:02 UTC9h 6m
2026-07-05 DAL84 - Jul 5, 04:05 UTCJul 5, 06:50 UTC2h 45m
2026-07-05 DAL84 ATL → CDG Jul 5, 04:03 UTCJul 5, 11:59 UTC7h 56m
2026-07-04 DAL223 ATH → ATL Jul 4, 06:55 UTCJul 4, 18:30 UTC11h 35m
2026-07-04 DAL223 ATH → ATL Jul 4, 06:53 UTCJul 4, 18:28 UTC11h 35m
2026-07-03 DAL240 BOS → ATH Jul 3, 19:50 UTCJul 4, 04:06 UTC8h 16m
2026-07-03 DAL240 BOS → ATH Jul 3, 19:50 UTCJul 4, 03:45 UTC7h 55m
2026-07-03 DAL243 AMS → BOS Jul 3, 09:58 UTCJul 3, 17:25 UTC7h 27m
2026-07-03 DAL243 AMS → BOS Jul 3, 10:00 UTCJul 3, 17:25 UTC7h 25m
2026-07-02 DAL142 SEA → AMS Jul 2, 21:40 UTCJul 3, 06:40 UTC9h 0m
2026-07-02 DAL143 - Jul 2, 08:45 UTCJul 2, 09:45 UTC1h 0m
2026-07-02 DAL143 AMS → SEA Jul 2, 08:40 UTCJul 2, 18:13 UTC9h 33m
2026-07-01 DAL256 - Jul 1, 21:00 UTCJul 2, 03:05 UTC6h 5m
2026-07-01 DAL225 - Jul 1, 10:15 UTCJul 1, 17:25 UTC7h 10m
2026-07-01 DAL225 CDG → BOS Jul 1, 10:10 UTCJul 1, 17:22 UTC7h 12m
2026-06-30 DAL220 SLC → CDG Jun 30, 21:50 UTCJul 1, 07:15 UTC9h 25m
2026-06-30 DAL220 SLC → CDG Jun 30, 21:48 UTCJul 1, 07:15 UTC9h 27m
2026-06-30 DAL57 - Jun 30, 09:30 UTCJun 30, 09:45 UTC15m
2026-06-30 DAL57 AMS → SLC Jun 30, 09:25 UTCJun 30, 18:56 UTC9h 31m
2026-06-29 DAL142 SEA → AMS Jun 29, 21:34 UTCJun 29, 23:34 UTC2h 0m
2026-06-29 DAL142 SEA → AMS Jun 29, 21:34 UTCJun 30, 06:47 UTC9h 13m
2026-06-28 DAL21 - Jun 28, 18:00 UTCJun 29, 02:54 UTC8h 55m
2026-06-28 DAL20 SEA → LHR Jun 28, 05:15 UTCJun 28, 13:45 UTC8h 30m
2026-06-28 DAL20 SEA → LHR Jun 28, 05:14 UTCJun 28, 14:13 UTC8h 59m

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 1h ago.
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 DAL3, DAL164, DAL9, DAL145, DAL49.