Apparatus

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sensors Mode-S transponder

A539C9

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N436DX · AIRBUS A-330-900 · operated by BANK OF UTAH TRUSTEE

Hex
A539C9
Octal
51234711
Decimal
10,828,233
Country
US
Tail
N436DX
Type
A339
Broadcasting now · callsign DAL20 · 37,000 ft
Flights observed
324
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:10 UTC

Current position

A539C9 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A539C9 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
DAL133 - 11 2026-06-25
DAL132 - 11 2026-07-13
DAL273 - 9 2026-07-04
DAL58 - 8 2026-07-12
DAL272 - 8 2026-07-04
DAL240 - 8 2026-07-15
DAL215 Delta Air Lines 8 2026-07-24
DAL17 - 8 2026-07-13
DAL223 - 7 2026-07-16
DAL157 - 7 2026-07-02
DAL108 - 7 2026-07-17
DAL70 Delta Air Lines 6 2026-05-18
DAL241 Delta Air Lines 6 2026-07-25
DAL225 Delta Air Lines 6 2026-07-20
DAL214 Delta Air Lines 6 2026-07-23
DAL71 Delta Air Lines 5 2026-05-18
DAL67 Delta Air Lines 5 2026-05-14
DAL63 - 5 2026-07-17
DAL57 Delta Air Lines 5 2026-07-19
DAL55 - 5 2026-06-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 DAL221 CDG → SLC Jul 26, 09:45 UTCJul 26, 20:05 UTC10h 20m
2026-07-26 DAL224 SEA → AMS Jul 26, 00:15 UTCJul 26, 06:30 UTC6h 15m
2026-07-25 DAL241 ATH → BOS Jul 25, 11:54 UTCJul 25, 21:35 UTC9h 41m
2026-07-25 DAL241 ATH → BOS Jul 25, 11:55 UTCJul 25, 21:35 UTC9h 40m
2026-07-24 DAL222 ATL → ATH Jul 24, 22:20 UTCJul 25, 01:20 UTC3h 0m
2026-07-24 DAL222 ATL → ATH Jul 24, 22:15 UTCJul 25, 08:26 UTC10h 11m
2026-07-24 DAL215 FCO → ATL Jul 24, 09:10 UTCJul 24, 19:05 UTC9h 55m
2026-07-24 DAL215 FCO → ATL Jul 24, 09:09 UTCJul 24, 19:24 UTC10h 15m
2026-07-23 DAL214 ATL → FCO Jul 23, 20:20 UTCJul 23, 23:20 UTC3h 0m
2026-07-23 DAL214 ATL → FCO Jul 23, 20:19 UTCJul 24, 05:23 UTC9h 4m
2026-07-22 DAL110 EZE → ATL Jul 22, 23:20 UTCJul 23, 09:10 UTC9h 50m
2026-07-22 DAL101 ATL → EZE Jul 22, 04:05 UTCJul 22, 13:35 UTC9h 30m
2026-07-21 DAL109 MAD → ATL Jul 21, 08:10 UTCJul 21, 16:50 UTC8h 40m
2026-07-20 DAL62 ATL → FCO Jul 20, 21:45 UTCJul 21, 04:10 UTC6h 24m
2026-07-20 DAL62 ATL → FCO Jul 20, 21:41 UTCJul 21, 04:05 UTC6h 24m
2026-07-20 DAL225 CDG → BOS Jul 20, 10:15 UTCJul 20, 17:20 UTC7h 5m
2026-07-19 DAL220 - Jul 19, 22:00 UTCJul 20, 07:15 UTC9h 15m
2026-07-19 DAL57 AMS → SLC Jul 19, 09:18 UTCJul 19, 19:09 UTC9h 51m
2026-07-19 DAL57 AMS → SLC Jul 19, 09:20 UTCJul 19, 19:15 UTC9h 55m
2026-07-18 DAL142 SEA → AMS Jul 18, 21:23 UTCJul 19, 06:24 UTC9h 1m
2026-07-18 DAL142 - Jul 18, 21:25 UTCJul 19, 02:10 UTC4h 45m
2026-07-18 DAL143 - Jul 18, 08:45 UTCJul 18, 18:30 UTC9h 45m
2026-07-17 DAL242 BOS → AMS Jul 17, 23:30 UTCJul 18, 06:00 UTC6h 31m
2026-07-17 DAL63 - Jul 17, 13:00 UTCJul 17, 20:10 UTC7h 10m
2026-07-17 DAL63 MAD → BOS Jul 17, 12:55 UTCJul 17, 20:03 UTC7h 8m
2026-07-17 DAL108 ATL → MAD Jul 17, 02:45 UTCJul 17, 10:30 UTC7h 45m
2026-07-17 DAL108 ATL → MAD Jul 17, 02:40 UTCJul 17, 10:34 UTC7h 54m
2026-07-16 DAL223 ATH → ATL Jul 16, 07:05 UTCJul 16, 18:34 UTC11h 30m
2026-07-15 DAL240 BOS → ATH Jul 15, 19:45 UTCJul 16, 04:15 UTC8h 30m
2026-07-15 DAL225 - Jul 15, 10:15 UTCJul 15, 17:20 UTC7h 5m
2026-07-14 DAL220 SLC → CDG Jul 14, 21:35 UTCJul 15, 07:05 UTC9h 29m
2026-07-14 DAL220 SLC → CDG Jul 14, 21:35 UTCJul 15, 07:11 UTC9h 36m
2026-07-14 DAL57 - Jul 14, 09:10 UTCJul 14, 18:50 UTC9h 40m
2026-07-13 DAL132 - Jul 13, 20:40 UTCJul 14, 04:15 UTC7h 35m
2026-07-13 DAL132 DTW → AMS Jul 13, 20:38 UTCJul 14, 04:15 UTC7h 37m
2026-07-13 DAL17 - Jul 13, 10:05 UTCJul 13, 11:25 UTC1h 20m
2026-07-13 DAL17 LHR → DTW Jul 13, 10:02 UTCJul 13, 17:39 UTC7h 37m
2026-07-12 DAL58 BOS → LHR Jul 12, 23:23 UTCJul 13, 05:35 UTC6h 12m
2026-07-12 DAL58 - Jul 12, 23:25 UTCJul 13, 05:40 UTC6h 15m
2026-07-12 DAL257 AMS → BOS Jul 12, 13:04 UTCJul 12, 19:52 UTC6h 48m
2026-07-12 DAL257 - Jul 12, 13:05 UTCJul 12, 14:45 UTC1h 40m
2026-07-12 DAL144 SEA → AMS Jul 12, 01:12 UTCJul 12, 10:13 UTC9h 1m
2026-07-12 DAL144 - Jul 12, 01:15 UTCJul 12, 01:55 UTC40m
2026-07-11 DAL43 FCO → SEA Jul 11, 10:40 UTCJul 11, 22:15 UTC11h 35m
2026-07-10 DAL42 SEA → FCO Jul 10, 21:30 UTCJul 11, 08:06 UTC10h 36m
2026-07-10 DAL42 - Jul 10, 21:30 UTCJul 10, 22:15 UTC45m
2026-07-09 DAL21 - Jul 9, 17:20 UTCJul 9, 18:15 UTC55m
2026-07-09 DAL21 LHR → SEA Jul 9, 17:19 UTCJul 10, 02:40 UTC9h 21m
2026-07-09 DAL20 - Jul 9, 05:25 UTCJul 9, 08:05 UTC2h 40m
2026-07-09 DAL20 SEA → LHR Jul 9, 05:25 UTCJul 9, 14:39 UTC9h 14m

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 N436DX page for operator, model, and routing details .

Mode-S A539C9 frequently asked

What is Mode-S code A539C9?
A539C9 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N436DX.
Where is Mode-S A539C9 registered?
Mode-S code A539C9 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 A539C9 broadcasting right now?
Yes. Mode-S A539C9 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A539C9, octal 51234711, decimal 10,828,233.
What flights does A539C9 operate?
Mode-S A539C9 has broadcast 20 distinct callsigns, including DAL133, DAL132, DAL273, DAL58, DAL272.