Apparatus

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sensors Mode-S transponder

AC9923

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N91007 · BOEING 787-10 Dreamliner · operated by UNITED AIRLINES INC

Hex
AC9923
Octal
53114443
Decimal
11,311,395
Country
US
Tail
N91007
Type
B78X
No current signal · last broadcast Jul 26, 21:35 UTC
Flights observed
225
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:35 UTC

Last known position

Most recent position reported by Mode-S AC9923.

Country allocation

The ICAO 24-bit address AC9923 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
UAL219 United Airlines 24 2026-07-20
UAL218 United Airlines 23 2026-07-21
UAL65 United Airlines 12 2026-07-26
UAL64 United Airlines 12 2026-07-26
UAL124 United Airlines 12 2026-07-26
UAL845 - 10 2026-07-18
UAL995 - 8 2026-07-08
UAL972 - 8 2026-07-07
UAL39 - 8 2026-07-13
UAL38 - 8 2026-07-22
UAL125 - 8 2026-07-09
UAL986 - 7 2026-07-15
UAL971 - 7 2026-07-16
UAL882 - 7 2026-07-14
UAL945 United Airlines 6 2026-05-21
UAL881 United Airlines 6 2026-07-21
UAL987 - 5 2026-07-15
UAL944 United Airlines 5 2026-05-20
UAL844 United Airlines 5 2026-07-19
UAL970 - 4 2026-07-15

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL124 EWR → ATH Jul 26, 20:05 UTCJul 26, 21:35 UTC1h 30m
2026-07-26 UAL65 LIS → EWR Jul 26, 10:05 UTCJul 26, 16:50 UTC6h 45m
2026-07-26 UAL64 EWR → LIS Jul 26, 00:56 UTCJul 26, 06:55 UTC5h 59m
2026-07-26 UAL64 EWR → LIS Jul 26, 00:40 UTCJul 26, 06:45 UTC6h 6m
2026-07-24 UAL1981 DEN → LGA Jul 24, 18:30 UTCJul 24, 23:10 UTC4h 40m
2026-07-24 UAL2445 GSP → ORD Jul 24, 11:25 UTCJul 24, 16:20 UTC4h 55m
2026-07-24 UAL2397 EWR → PDX Jul 24, 04:25 UTCJul 24, 08:45 UTC4h 20m
2026-07-23 UAL212 DEN → SBA Jul 23, 16:30 UTCJul 23, 21:25 UTC4h 55m
2026-07-23 UAL2303 IAD → SAN Jul 23, 06:50 UTCJul 23, 11:15 UTC4h 25m
2026-07-22 UAL38 - Jul 22, 10:20 UTCJul 22, 19:30 UTC9h 10m
2026-07-21 UAL38 - Jul 21, 22:50 UTCJul 22, 19:30 UTC20h 40m
2026-07-21 UAL38 - Jul 21, 22:40 UTCJul 22, 19:30 UTC20h 50m
2026-07-21 UAL881 ORD → HND Jul 21, 18:50 UTCJul 22, 18:45 UTC23h 55m
2026-07-21 UAL881 ORD → HND Jul 21, 17:46 UTCJul 22, 06:09 UTC12h 23m
2026-07-21 UAL881 ORD → HND Jul 21, 17:45 UTCJul 21, 23:45 UTC6h 0m
2026-07-21 UAL218 HNL → ORD Jul 21, 06:00 UTCJul 21, 09:30 UTC3h 30m
2026-07-20 UAL219 ORD → HNL Jul 20, 15:15 UTCJul 20, 23:15 UTC8h 0m
2026-07-20 UAL218 HNL → ORD Jul 20, 06:00 UTCJul 20, 09:40 UTC3h 40m
2026-07-20 UAL218 HNL → ORD Jul 20, 02:15 UTCJul 20, 02:25 UTC10m
2026-07-19 UAL219 ORD → HNL Jul 19, 22:55 UTCJul 19, 23:15 UTC20m
2026-07-19 UAL219 ORD → HNL Jul 19, 15:05 UTCJul 19, 18:50 UTC3h 45m
2026-07-19 UAL844 GRU → ORD Jul 19, 01:30 UTCJul 19, 11:10 UTC9h 40m
2026-07-18 UAL845 - Jul 18, 03:40 UTCJul 18, 08:35 UTC4h 55m
2026-07-18 UAL845 ORD → GRU Jul 18, 03:03 UTCJul 18, 13:23 UTC10h 20m
2026-07-17 UAL423 ATH → ORD Jul 17, 12:10 UTCJul 17, 22:35 UTC10h 25m
2026-07-16 UAL422 - Jul 16, 22:40 UTCJul 17, 08:15 UTC9h 35m
2026-07-16 UAL422 ORD → ATH Jul 16, 22:08 UTCJul 17, 08:07 UTC9h 59m
2026-07-16 UAL971 - Jul 16, 08:55 UTCJul 16, 18:10 UTC9h 15m
2026-07-15 UAL970 - Jul 15, 22:00 UTCJul 16, 06:30 UTC8h 30m
2026-07-15 UAL986 - Jul 15, 09:45 UTCJul 15, 17:30 UTC7h 45m
2026-07-15 UAL986 CDG → ORD Jul 15, 09:43 UTCJul 15, 17:09 UTC7h 26m
2026-07-15 UAL987 ORD → CDG Jul 15, 00:00 UTCJul 15, 07:25 UTC7h 25m
2026-07-14 UAL882 HND → ORD Jul 14, 08:45 UTCJul 14, 19:50 UTC11h 5m
2026-07-13 UAL39 - Jul 13, 19:00 UTCJul 14, 05:25 UTC10h 25m
2026-07-12 UAL38 HND → LAX Jul 12, 09:45 UTCJul 12, 19:40 UTC9h 55m
2026-07-11 UAL39 - Jul 11, 19:15 UTCJul 11, 20:15 UTC1h 0m
2026-07-11 UAL39 LAX → HND Jul 11, 19:02 UTCJul 12, 05:50 UTC10h 48m
2026-07-11 UAL2445 EWR → LAX Jul 11, 11:15 UTCJul 11, 16:15 UTC5h 0m
2026-07-11 UAL2397 LAX → EWR Jul 11, 04:10 UTCJul 11, 08:30 UTC4h 20m
2026-07-10 UAL2238 - Jul 10, 21:00 UTCJul 11, 02:05 UTC5h 5m
2026-07-10 UAL65 LIS → EWR Jul 10, 10:05 UTCJul 10, 17:05 UTC7h 0m
2026-07-10 UAL65 LIS → EWR Jul 10, 09:54 UTCJul 10, 17:08 UTC7h 14m
2026-07-10 UAL64 EWR → LIS Jul 10, 01:40 UTCJul 10, 07:30 UTC5h 50m
2026-07-09 UAL125 ATH → EWR Jul 9, 07:35 UTCJul 9, 17:35 UTC10h 0m
2026-07-08 UAL124 EWR → ATH Jul 8, 20:18 UTCJul 9, 04:58 UTC8h 40m
2026-07-08 UAL124 - Jul 8, 20:15 UTCJul 9, 04:55 UTC8h 40m
2026-07-08 UAL995 BRU → EWR Jul 8, 09:40 UTCJul 8, 17:00 UTC7h 20m
2026-07-08 UAL995 BRU → EWR Jul 8, 09:24 UTCJul 8, 16:59 UTC7h 35m
2026-07-07 UAL972 ORD → BRU Jul 7, 23:57 UTCJul 8, 06:36 UTC6h 39m
2026-07-07 UAL972 - Jul 7, 23:25 UTCJul 8, 06:45 UTC7h 20m

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 N91007 page for operator, model, and routing details .

Mode-S AC9923 frequently asked

What is Mode-S code AC9923?
AC9923 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N91007.
Where is Mode-S AC9923 registered?
Mode-S code AC9923 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 AC9923 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:35 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC9923, octal 53114443, decimal 11,311,395.
What flights does AC9923 operate?
Mode-S AC9923 has broadcast 20 distinct callsigns, including UAL219, UAL218, UAL65, UAL64, UAL124.