Apparatus

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sensors Mode-S transponder

ACC3B4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N921US · AIRBUS A-321 · operated by AMERICAN AIRLINES INC

Hex
ACC3B4
Octal
53141664
Decimal
11,322,292
Country
US
Tail
N921US
Type
A321
Transponder active on ground
Flights observed
523
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Last known position

Most recent position reported by Mode-S ACC3B4.

Country allocation

The ICAO 24-bit address ACC3B4 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
AAL636 American Airlines 7 2026-04-16
AAL1150 - 7 2026-06-27
AAL2053 American Airlines 6 2026-05-06
AAL1758 American Airlines 6 2026-06-01
AAL599 - 5 2026-07-11
AAL3245 - 5 2026-07-18
AAL2791 American Airlines 5 2026-07-06
AAL2356 American Airlines 5 2026-04-23
AAL793 - 4 2026-07-12
AAL717 - 4 2026-07-07
AAL364 American Airlines 4 2026-07-25
AAL2842 - 4 2026-06-27
AAL2822 - 4 2026-07-09
AAL2704 American Airlines 4 2026-04-16
AAL2584 - 4 2026-07-22
AAL215 American Airlines 4 2026-04-28
AAL2136 American Airlines 4 2026-05-08
AAL1704 American Airlines 4 2026-05-22
AAL1662 American Airlines 4 2026-05-11
AAL852 American Airlines 3 2026-04-25

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 AAL2329 MIA → PHL Jul 26, 22:50 UTCJul 26, 23:00 UTC10m
2026-07-26 AAL2777 DFW → LGA Jul 26, 20:20 UTCJul 26, 21:40 UTC1h 20m
2026-07-26 AAL854 SEA → CLT Jul 26, 14:20 UTCJul 26, 18:35 UTC4h 15m
2026-07-25 AAL2107 CMH → DFW Jul 25, 21:15 UTCJul 26, 02:15 UTC5h 0m
2026-07-25 AAL2107 CMH → DFW Jul 25, 21:11 UTCJul 26, 02:15 UTC5h 4m
2026-07-25 AAL2792 SAT → DFW Jul 25, 17:10 UTCJul 25, 19:20 UTC2h 10m
2026-07-25 AAL895 CLT → CUN Jul 25, 13:20 UTCJul 25, 15:30 UTC2h 10m
2026-07-25 AAL1896 MCO → CLT Jul 25, 10:15 UTCJul 25, 11:30 UTC1h 15m
2026-07-25 AAL364 DFW → SJC Jul 25, 02:50 UTCJul 25, 05:25 UTC2h 35m
2026-07-24 AAL3260 GJT → PHX Jul 24, 22:50 UTCJul 25, 01:20 UTC2h 30m
2026-07-24 AAL2912 ORD → XNA Jul 24, 18:45 UTCJul 24, 20:15 UTC1h 30m
2026-07-24 AAL1886 - Jul 24, 14:40 UTCJul 24, 17:05 UTC2h 25m
2026-07-24 AAL972 DFW → AUS Jul 24, 03:10 UTCJul 24, 03:45 UTC35m
2026-07-23 AAL2634 LAX → PHL Jul 23, 22:45 UTCJul 24, 01:35 UTC2h 50m
2026-07-23 AAL2634 LAX → PHL Jul 23, 22:41 UTCJul 24, 01:34 UTC2h 53m
2026-07-23 AAL2634 LAX → PHL Jul 23, 18:25 UTCJul 23, 21:25 UTC3h 0m
2026-07-23 AAL1021 BUF → DFW Jul 23, 13:50 UTCJul 23, 16:45 UTC2h 55m
2026-07-23 AAL509 LGA → RDU Jul 23, 04:35 UTCJul 23, 07:35 UTC3h 0m
2026-07-22 AAL3104 ATL → DFW Jul 22, 23:45 UTCJul 23, 02:10 UTC2h 25m
2026-07-22 AAL3104 ATL → DFW Jul 22, 23:41 UTCJul 23, 02:07 UTC2h 26m
2026-07-22 AAL2584 - Jul 22, 21:15 UTCJul 22, 21:45 UTC30m
2026-07-22 AAL2584 - Jul 22, 19:25 UTCJul 22, 19:40 UTC15m
2026-07-22 AAL2584 - Jul 22, 17:35 UTCJul 22, 17:45 UTC10m
2026-07-22 AAL2584 - Jul 22, 15:30 UTCJul 22, 16:00 UTC30m
2026-07-22 AAL1249 LGA → MIA Jul 22, 11:10 UTCJul 22, 13:15 UTC2h 5m
2026-07-22 AAL1389 MIA → LGA Jul 22, 02:20 UTCJul 22, 05:15 UTC2h 55m
2026-07-21 AAL2367 EWR → DFW Jul 21, 15:10 UTCJul 21, 20:30 UTC5h 20m
2026-07-21 AAL873 BOS → MIA Jul 21, 10:23 UTCJul 21, 13:09 UTC2h 46m
2026-07-21 AAL873 BOS → MIA Jul 21, 10:25 UTCJul 21, 13:10 UTC2h 45m
2026-07-21 AAL1054 MIA → BOS Jul 21, 02:50 UTCJul 21, 05:35 UTC2h 45m
2026-07-20 AAL605 MIA → LGA Jul 20, 22:50 UTCJul 21, 01:25 UTC2h 35m
2026-07-20 AAL3229 - Jul 20, 17:20 UTCJul 20, 20:05 UTC2h 45m
2026-07-20 AAL3290 - Jul 20, 13:15 UTCJul 20, 15:45 UTC2h 30m
2026-07-20 AAL3006 - Jul 20, 09:05 UTCJul 20, 11:40 UTC2h 35m
2026-07-20 AAL711 MIA → CLE Jul 20, 04:50 UTCJul 20, 07:10 UTC2h 20m
2026-07-19 AAL2388 - Jul 19, 23:30 UTCJul 20, 02:35 UTC3h 5m
2026-07-19 AAL2388 LGA → DFW Jul 19, 23:26 UTCJul 20, 02:38 UTC3h 12m
2026-07-19 AAL2388 DFW → LGA Jul 19, 17:45 UTCJul 19, 20:55 UTC3h 10m
2026-07-19 AAL1018 PHX → DFW Jul 19, 14:20 UTCJul 19, 16:20 UTC2h 0m
2026-07-19 AAL1018 PHX → DFW Jul 19, 14:18 UTCJul 19, 16:21 UTC2h 3m
2026-07-19 AAL1022 PHL → PWM Jul 19, 04:27 UTCJul 19, 05:10 UTC43m
2026-07-19 AAL1022 PHL → PWM Jul 19, 04:30 UTCJul 19, 05:15 UTC45m
2026-07-19 AAL1022 PHL → PWM Jul 19, 01:45 UTCJul 19, 02:30 UTC45m
2026-07-18 AAL1155 DFW → PHX Jul 18, 21:55 UTCJul 19, 00:00 UTC2h 5m
2026-07-18 AAL3245 TPA → DFW Jul 18, 18:10 UTCJul 18, 20:25 UTC2h 15m
2026-07-18 AAL3245 TPA → DFW Jul 18, 18:08 UTCJul 18, 20:21 UTC2h 13m
2026-07-18 AAL3245 DFW → TPA Jul 18, 14:45 UTCJul 18, 16:50 UTC2h 5m
2026-07-18 AAL2975 MCO → DFW Jul 18, 10:35 UTCJul 18, 12:50 UTC2h 15m
2026-07-18 AAL364 DFW → SJC Jul 18, 04:20 UTCJul 18, 06:30 UTC2h 10m
2026-07-18 AAL2385 MCO → DFW Jul 18, 00:32 UTCJul 18, 02:55 UTC2h 23m

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 N921US page for operator, model, and routing details .

Mode-S ACC3B4 frequently asked

What is Mode-S code ACC3B4?
ACC3B4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N921US.
Where is Mode-S ACC3B4 registered?
Mode-S code ACC3B4 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 ACC3B4 broadcasting right now?
Mode-S ACC3B4 is currently broadcasting from the ground.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex ACC3B4, octal 53141664, decimal 11,322,292.
What flights does ACC3B4 operate?
Mode-S ACC3B4 has broadcast 20 distinct callsigns, including AAL636, AAL1150, AAL2053, AAL1758, AAL599.