Apparatus

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sensors Mode-S transponder

A51601

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N427DX · AIRBUS A-330-900 · operated by DELTA AIR LINES INC

Hex
A51601
Octal
51213001
Decimal
10,819,073
Country
US
Tail
N427DX
Type
A339
No current signal · last broadcast 3h ago
Flights observed
249
Distinct callsigns
20
Country
US
Last broadcast
3h ago

Last known position

Most recent position reported by Mode-S A51601.

Country allocation

The ICAO 24-bit address A51601 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
DAL81 - 12 2026-07-13
DAL273 Delta Air Lines 11 2026-06-11
DAL80 - 9 2026-07-13
DAL226 Delta Air Lines 9 2026-06-04
DAL43 - 8 2026-07-09
DAL21 - 8 2026-06-19
DAL272 Delta Air Lines 7 2026-06-11
DAL9 Delta Air Lines 6 2026-06-14
DAL3 - 6 2026-06-14
DAL20 - 6 2026-07-14
DAL164 - 6 2026-07-12
DAL157 Delta Air Lines 6 2026-06-10
DAL145 - 6 2026-07-12
DAL144 - 6 2026-07-10
DAL298 - 5 2026-06-16
DAL257 - 5 2026-07-07
DAL213 Delta Air Lines 5 2026-06-13
DAL212 Delta Air Lines 5 2026-06-13
DAL203 - 5 2026-06-12
DAL202 Delta Air Lines 5 2026-06-11

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 DAL20 - Jul 14, 04:55 UTCJul 14, 06:55 UTC2h 0m
2026-07-13 DAL81 - Jul 13, 14:50 UTCJul 13, 20:25 UTC5h 35m
2026-07-13 DAL81 CDG → SEA Jul 13, 14:49 UTCJul 14, 00:46 UTC9h 57m
2026-07-13 DAL81 CDG → SEA Jul 13, 14:49 UTCJul 14, 00:58 UTC10h 9m
2026-07-13 DAL80 - Jul 13, 01:50 UTCJul 13, 11:10 UTC9h 20m
2026-07-12 DAL145 AMS → SEA Jul 12, 13:41 UTCJul 12, 23:37 UTC9h 56m
2026-07-12 DAL145 - Jul 12, 13:45 UTCJul 12, 22:15 UTC8h 30m
2026-07-12 DAL164 - Jul 12, 02:55 UTCJul 12, 03:50 UTC55m
2026-07-12 DAL164 MSP → AMS Jul 12, 02:55 UTCJul 12, 10:45 UTC7h 50m
2026-07-11 DAL165 - Jul 11, 14:05 UTCJul 11, 22:30 UTC8h 25m
2026-07-11 DAL236 TPA → AMS Jul 11, 02:55 UTCJul 11, 11:25 UTC8h 30m
2026-07-10 DAL237 - Jul 10, 13:30 UTCJul 11, 00:20 UTC10h 50m
2026-07-10 DAL144 SEA → AMS Jul 10, 01:00 UTCJul 10, 10:10 UTC9h 10m
2026-07-09 DAL43 - Jul 9, 11:25 UTCJul 9, 19:25 UTC8h 0m
2026-07-09 DAL43 FCO → SEA Jul 9, 11:24 UTCJul 9, 22:25 UTC11h 1m
2026-07-08 DAL42 - Jul 8, 21:45 UTCJul 9, 08:35 UTC10h 50m
2026-07-08 DAL143 - Jul 8, 09:30 UTCJul 8, 19:05 UTC9h 35m
2026-07-08 DAL242 BOS → AMS Jul 8, 00:16 UTCJul 8, 06:43 UTC6h 27m
2026-07-08 DAL242 - Jul 8, 00:20 UTCJul 8, 01:40 UTC1h 20m
2026-07-07 DAL257 - Jul 7, 14:10 UTCJul 7, 21:30 UTC7h 20m
2026-07-07 DAL144 SEA → AMS Jul 7, 02:10 UTCJul 7, 11:10 UTC9h 0m
2026-07-06 DAL43 - Jul 6, 23:35 UTCJul 6, 23:40 UTC5m
2026-07-06 DAL43 - Jul 6, 11:50 UTCJul 6, 16:30 UTC4h 40m
2026-07-06 DAL43 FCO → SEA Jul 6, 11:47 UTCJul 6, 23:16 UTC11h 29m
2026-07-06 DAL66 - Jul 6, 00:25 UTCJul 6, 09:25 UTC9h 0m
2026-07-05 DAL297 SPN → NRT Jul 5, 09:05 UTCJul 5, 20:25 UTC11h 20m
2026-07-04 DAL296 HND → ATL Jul 4, 20:00 UTCJul 4, 23:05 UTC3h 5m
2026-07-04 DAL296 HND → ATL Jul 4, 19:58 UTCJul 5, 05:55 UTC9h 57m
2026-07-03 DAL110 - Jul 3, 23:20 UTCJul 4, 09:05 UTC9h 45m
2026-07-03 DAL101 ATL → EZE Jul 3, 03:25 UTCJul 3, 12:55 UTC9h 30m
2026-07-02 DAL297 SPN → NRT Jul 2, 09:45 UTCJul 2, 21:20 UTC11h 35m
2026-07-01 DAL296 HND → ATL Jul 1, 20:45 UTCJul 2, 07:10 UTC10h 25m
2026-06-30 DAL223 ATH → ATL Jun 30, 07:15 UTCJun 30, 18:20 UTC11h 5m
2026-06-29 DAL240 BOS → ATH Jun 29, 19:54 UTCJun 30, 04:15 UTC8h 21m
2026-06-29 DAL59 - Jun 29, 09:10 UTCJun 29, 10:15 UTC1h 5m
2026-06-29 DAL59 LHR → BOS Jun 29, 09:08 UTCJun 29, 15:48 UTC6h 40m
2026-06-29 DAL58 BOS → LHR Jun 29, 00:04 UTCJun 29, 05:53 UTC5h 49m
2026-06-29 DAL58 - Jun 29, 00:05 UTCJun 29, 01:25 UTC1h 20m
2026-06-28 DAL257 AMS → BOS Jun 28, 13:34 UTCJun 28, 20:50 UTC7h 15m
2026-06-27 DAL56 - Jun 27, 23:00 UTCJun 28, 08:09 UTC9h 10m
2026-06-27 DAL56 SLC → AMS Jun 27, 22:56 UTCJun 28, 08:07 UTC9h 11m
2026-06-27 DAL221 - Jun 27, 10:00 UTCJun 27, 20:19 UTC10h 20m
2026-06-25 DAL220 SLC → CDG Jun 25, 22:54 UTCJun 26, 01:10 UTC2h 15m
2026-06-25 DAL220 SLC → CDG Jun 25, 22:54 UTCJun 26, 08:21 UTC9h 27m
2026-06-25 DAL57 AMS → SLC Jun 25, 09:48 UTCJun 25, 19:37 UTC9h 49m
2026-06-25 DAL57 - Jun 25, 09:50 UTCJun 25, 10:15 UTC25m
2026-06-25 DAL256 BOS → AMS Jun 25, 00:24 UTCJun 25, 06:25 UTC6h 0m
2026-06-23 DAL257 AMS → BOS Jun 23, 13:12 UTCJun 23, 20:39 UTC7h 27m
2026-06-23 DAL257 - Jun 23, 13:15 UTCJun 23, 14:44 UTC1h 30m
2026-06-22 DAL56 SLC → AMS Jun 22, 23:45 UTCJun 23, 08:50 UTC9h 5m

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 N427DX page for operator, model, and routing details .

Mode-S A51601 frequently asked

What is Mode-S code A51601?
A51601 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N427DX.
Where is Mode-S A51601 registered?
Mode-S code A51601 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 A51601 broadcasting right now?
No active broadcast right now. Last signal was 3h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A51601, octal 51213001, decimal 10,819,073.
What flights does A51601 operate?
Mode-S A51601 has broadcast 20 distinct callsigns, including DAL81, DAL273, DAL80, DAL226, DAL43.