Apparatus

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sensors Mode-S transponder

A4B827

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N403DX · AIRBUS A-330-900 · operated by DELTA AIR LINES INC

Hex
A4B827
Octal
51134047
Decimal
10,795,047
Country
US
Tail
N403DX
Type
A339
Broadcasting now · callsign DAL223 · 36,000 ft
Flights observed
286
Distinct callsigns
20
Country
US
Last broadcast
50m ago

Current position

A4B827 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A4B827 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
DAL21 - 12 2026-07-08
DAL224 - 10 2026-07-03
DAL20 Delta Air Lines 9 2026-07-08
DAL4 Delta Air Lines 8 2026-06-04
DAL227 - 8 2026-06-15
DAL221 - 8 2026-07-04
DAL163 Delta Air Lines 8 2026-05-29
DAL56 - 7 2026-07-04
DAL241 Delta Air Lines 7 2026-05-27
DAL226 - 7 2026-06-15
DAL213 Delta Air Lines 7 2026-06-14
DAL202 Delta Air Lines 7 2026-06-12
DAL10 Delta Air Lines 7 2026-06-04
DAL81 Delta Air Lines 6 2026-07-07
DAL57 - 6 2026-07-10
DAL273 - 6 2026-06-18
DAL220 - 6 2026-07-10
DAL9 Delta Air Lines 5 2026-06-02
DAL80 - 5 2026-07-07
DAL272 - 5 2026-06-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 DAL223 - Jul 14, 07:00 UTCJul 14, 07:45 UTC45m
2026-07-14 DAL223 ATH → ATL Jul 14, 07:00 UTCJul 14, 18:15 UTC11h 15m
2026-07-13 DAL240 BOS → ATH Jul 13, 19:45 UTCJul 14, 04:25 UTC8h 40m
2026-07-13 DAL59 - Jul 13, 09:00 UTCJul 13, 15:25 UTC6h 25m
2026-07-12 DAL16 - Jul 12, 23:00 UTCJul 13, 06:20 UTC7h 20m
2026-07-12 DAL133 AMS → DTW Jul 12, 07:52 UTCJul 12, 15:39 UTC7h 47m
2026-07-12 DAL133 - Jul 12, 07:55 UTCJul 12, 13:45 UTC5h 50m
2026-07-11 DAL256 - Jul 11, 21:00 UTCJul 12, 03:10 UTC6h 10m
2026-07-11 DAL225 - Jul 11, 10:45 UTCJul 11, 18:05 UTC7h 20m
2026-07-10 DAL220 - Jul 10, 21:45 UTCJul 10, 23:55 UTC2h 10m
2026-07-10 DAL220 SLC → CDG Jul 10, 21:43 UTCJul 11, 07:18 UTC9h 35m
2026-07-10 DAL57 AMS → SLC Jul 10, 09:10 UTCJul 10, 19:00 UTC9h 50m
2026-07-10 DAL57 - Jul 10, 09:15 UTCJul 10, 09:45 UTC30m
2026-07-09 DAL142 SEA → AMS Jul 9, 21:17 UTCJul 10, 06:18 UTC9h 1m
2026-07-09 DAL142 SEA → AMS Jul 9, 21:20 UTCJul 10, 06:15 UTC8h 55m
2026-07-08 DAL21 - Jul 8, 17:05 UTCJul 9, 02:10 UTC9h 5m
2026-07-08 DAL20 SEA → LHR Jul 8, 05:10 UTCJul 8, 14:20 UTC9h 10m
2026-07-07 DAL81 CDG → SEA Jul 7, 14:25 UTCJul 8, 00:25 UTC10h 0m
2026-07-07 DAL81 CDG → SEA Jul 7, 14:21 UTCJul 8, 00:20 UTC9h 59m
2026-07-07 DAL80 SEA → CDG Jul 7, 02:17 UTCJul 7, 11:26 UTC9h 9m
2026-07-07 DAL80 - Jul 7, 02:20 UTCJul 7, 03:45 UTC1h 25m
2026-07-06 DAL145 AMS → SEA Jul 6, 13:40 UTCJul 6, 23:30 UTC9h 50m
2026-07-06 DAL164 MSP → AMS Jul 6, 03:01 UTCJul 6, 10:45 UTC7h 44m
2026-07-06 DAL164 - Jul 6, 03:05 UTCJul 6, 03:45 UTC40m
2026-07-05 DAL165 AMS → MSP Jul 5, 13:25 UTCJul 5, 21:40 UTC8h 15m
2026-07-05 DAL165 AMS → MSP Jul 5, 13:23 UTCJul 5, 21:44 UTC8h 21m
2026-07-04 DAL56 SLC → AMS Jul 4, 22:40 UTCJul 5, 07:50 UTC9h 10m
2026-07-04 DAL221 - Jul 4, 09:25 UTCJul 4, 19:45 UTC10h 20m
2026-07-03 DAL224 BOS → CDG Jul 3, 23:35 UTCJul 4, 05:44 UTC6h 9m
2026-07-03 DAL224 - Jul 3, 23:35 UTCJul 4, 01:00 UTC1h 25m
2026-07-03 DAL63 FCO → ATL Jul 3, 13:00 UTCJul 3, 20:00 UTC7h 0m
2026-07-03 DAL108 ATL → MAD Jul 3, 01:55 UTCJul 3, 09:55 UTC8h 0m
2026-07-02 DAL109 - Jul 2, 08:10 UTCJul 2, 09:25 UTC1h 15m
2026-07-02 DAL109 MAD → ATL Jul 2, 08:09 UTCJul 2, 16:44 UTC8h 35m
2026-07-02 DAL109 MAD → ATL Jul 2, 08:09 UTCJul 2, 16:54 UTC8h 45m
2026-07-01 DAL62 ATL → FCO Jul 1, 22:05 UTCJul 2, 04:35 UTC6h 30m
2026-07-01 DAL125 LIS → BOS Jul 1, 12:00 UTCJul 1, 18:35 UTC6h 35m
2026-07-01 DAL124 BOS → LIS Jul 1, 03:45 UTCJul 1, 09:50 UTC6h 5m
2026-06-30 DAL257 - Jun 30, 20:15 UTCJun 30, 21:15 UTC1h 0m
2026-06-30 DAL257 - Jun 30, 14:20 UTCJun 30, 20:10 UTC5h 50m
2026-06-30 DAL144 - Jun 30, 02:50 UTCJun 30, 04:45 UTC1h 55m
2026-06-30 DAL144 SEA → AMS Jun 30, 02:46 UTCJun 30, 11:54 UTC9h 8m
2026-06-29 DAL43 LAX → SYD Jun 29, 10:55 UTCJun 29, 19:09 UTC8h 15m
2026-06-29 DAL43 LAX → SYD Jun 29, 10:53 UTCJun 29, 21:45 UTC10h 52m
2026-06-28 DAL42 SYD → LAX Jun 28, 21:45 UTCJun 29, 08:35 UTC10h 50m
2026-06-27 DAL21 - Jun 27, 16:59 UTCJun 27, 17:44 UTC45m
2026-06-27 DAL21 LHR → SEA Jun 27, 16:59 UTCJun 28, 01:58 UTC8h 59m
2026-06-27 DAL20 SEA → LHR Jun 27, 05:29 UTCJun 27, 05:44 UTC15m
2026-06-27 DAL20 SEA → LHR Jun 27, 05:29 UTCJun 27, 14:28 UTC8h 59m
2026-06-26 DAL21 - Jun 26, 17:04 UTCJun 26, 19:39 UTC2h 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 N403DX page for operator, model, and routing details .

Mode-S A4B827 frequently asked

What is Mode-S code A4B827?
A4B827 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N403DX.
Where is Mode-S A4B827 registered?
Mode-S code A4B827 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 A4B827 broadcasting right now?
Yes. Mode-S A4B827 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A4B827, octal 51134047, decimal 10,795,047.
What flights does A4B827 operate?
Mode-S A4B827 has broadcast 20 distinct callsigns, including DAL21, DAL224, DAL20, DAL4, DAL227.