Apparatus

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sensors Mode-S transponder

A4423A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37367 · BOEING 737 MAX 8 · operated by UNITED AIRLINES INC

Hex
A4423A
Octal
51041072
Decimal
10,764,858
Country
US
Tail
N37367
Type
B38M
No current signal · last broadcast Jul 26, 20:25 UTC
Flights observed
466
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:25 UTC

Last known position

Most recent position reported by Mode-S A4423A.

Country allocation

The ICAO 24-bit address A4423A 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
UAL1009 United Airlines 7 2026-07-21
UAL474 United Airlines 6 2026-07-20
UAL359 United Airlines 6 2026-07-20
UAL2007 - 6 2026-07-04
UAL1352 - 6 2026-07-17
UAL2224 United Airlines 5 2026-06-13
UAL1320 United Airlines 5 2026-07-17
UAL660 - 4 2026-07-19
UAL2386 - 4 2026-06-24
UAL2123 United Airlines 4 2026-04-17
UAL1952 United Airlines 4 2026-07-19
UAL1751 - 4 2026-07-04
UAL1523 United Airlines 4 2026-06-03
UAL1415 - 4 2026-07-02
UAL1245 United Airlines 4 2026-07-25
UAL1194 United Airlines 4 2026-04-15
UAL784 - 3 2026-04-13
UAL757 - 3 2026-07-13
UAL587 United Airlines 3 2026-04-30
UAL527 United Airlines 3 2026-07-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1589 IAH → LGA Jul 26, 17:15 UTCJul 26, 20:25 UTC3h 10m
2026-07-26 UAL2448 PHX → SFO Jul 26, 12:45 UTCJul 26, 16:00 UTC3h 15m
2026-07-26 UAL1097 BUR → SFO Jul 26, 06:40 UTCJul 26, 09:45 UTC3h 5m
2026-07-26 UAL1055 EWR → ATL Jul 26, 01:25 UTCJul 26, 04:35 UTC3h 10m
2026-07-25 UAL1245 EWR → DFW Jul 25, 20:40 UTCJul 25, 22:55 UTC2h 15m
2026-07-25 UAL1245 EWR → DFW Jul 25, 19:53 UTCJul 25, 22:50 UTC2h 57m
2026-07-25 UAL1244 MSP → SFO Jul 25, 14:55 UTCJul 25, 17:10 UTC2h 15m
2026-07-25 UAL1244 MSP → SFO Jul 25, 14:58 UTCJul 25, 18:06 UTC3h 8m
2026-07-24 UAL2083 UIO → IAH Jul 24, 23:30 UTCJul 25, 10:25 UTC10h 55m
2026-07-24 UAL527 XPL → IAH Jul 24, 18:45 UTCJul 24, 21:03 UTC2h 18m
2026-07-24 UAL527 XPL → IAH Jul 24, 14:55 UTCJul 24, 21:05 UTC6h 10m
2026-07-24 UAL2606 ORD → LGA Jul 24, 10:55 UTCJul 24, 12:55 UTC2h 0m
2026-07-24 UAL1829 EWR → SFO Jul 24, 01:50 UTCJul 24, 03:55 UTC2h 5m
2026-07-23 UAL1245 EWR → DFW Jul 23, 15:00 UTCJul 24, 00:05 UTC9h 5m
2026-07-23 UAL1229 EWR → MCI Jul 23, 10:25 UTCJul 23, 12:30 UTC2h 5m
2026-07-23 UAL1229 EWR → MCI Jul 23, 10:28 UTCJul 23, 12:46 UTC2h 18m
2026-07-23 UAL2237 ORD → EWR Jul 23, 02:40 UTCJul 23, 04:55 UTC2h 15m
2026-07-22 UAL643 KOA → SFO Jul 22, 22:10 UTCJul 23, 01:10 UTC3h 0m
2026-07-22 UAL2780 IAD → EWR Jul 22, 17:50 UTCJul 22, 20:35 UTC2h 45m
2026-07-22 UAL2748 GSO → EWR Jul 22, 12:15 UTCJul 22, 16:00 UTC3h 45m
2026-07-22 UAL2748 GSO → EWR Jul 22, 12:15 UTCJul 22, 15:58 UTC3h 43m
2026-07-22 UAL2820 IAH → SFO Jul 22, 01:45 UTCJul 22, 05:25 UTC3h 40m
2026-07-21 UAL1009 EWR → MCO Jul 21, 23:35 UTCJul 21, 23:40 UTC5m
2026-07-21 UAL1009 EWR → MCO Jul 21, 19:55 UTCJul 21, 23:40 UTC3h 45m
2026-07-21 UAL1009 EWR → MCO Jul 21, 19:48 UTCJul 21, 23:19 UTC3h 31m
2026-07-21 UAL1008 BOS → SFO Jul 21, 14:05 UTCJul 21, 17:55 UTC3h 50m
2026-07-20 UAL474 MEX → ORD Jul 20, 20:45 UTCJul 21, 00:50 UTC4h 4m
2026-07-20 UAL359 ORD → MEX Jul 20, 14:55 UTCJul 20, 18:25 UTC3h 30m
2026-07-19 UAL1009 EWR → MCO Jul 19, 19:50 UTCJul 19, 23:40 UTC3h 50m
2026-07-19 UAL1008 - Jul 19, 14:05 UTCJul 19, 17:45 UTC3h 40m
2026-07-19 UAL660 - Jul 19, 10:20 UTCJul 19, 12:20 UTC2h 0m
2026-07-19 UAL8137 ORD → PHL Jul 19, 06:10 UTCJul 19, 07:30 UTC1h 20m
2026-07-19 UAL1952 LGA → IAH Jul 19, 02:30 UTCJul 19, 02:35 UTC5m
2026-07-19 UAL1952 LGA → IAH Jul 19, 01:35 UTCJul 19, 02:30 UTC55m
2026-07-19 UAL1952 LGA → IAH Jul 19, 01:32 UTCJul 19, 02:15 UTC43m
2026-07-18 UAL1952 LGA → IAH Jul 18, 19:25 UTCJul 18, 23:55 UTC4h 30m
2026-07-18 UAL1135 - Jul 18, 13:20 UTCJul 18, 17:55 UTC4h 35m
2026-07-17 UAL1352 - Jul 17, 23:00 UTCJul 18, 02:50 UTC3h 51m
2026-07-17 UAL1320 SFO → ONT Jul 17, 18:40 UTCJul 17, 20:35 UTC1h 55m
2026-07-17 UAL2750 - Jul 17, 12:15 UTCJul 17, 15:44 UTC3h 30m
2026-07-17 UAL2750 ALB → DEN Jul 17, 12:13 UTCJul 17, 15:41 UTC3h 28m
2026-07-17 UAL1662 DEN → ALB Jul 17, 00:45 UTCJul 17, 03:55 UTC3h 10m
2026-07-16 UAL2132 - Jul 16, 21:00 UTCJul 16, 23:10 UTC2h 10m
2026-07-16 UAL643 - Jul 16, 18:34 UTCJul 16, 19:45 UTC1h 10m
2026-07-16 UAL2317 - Jul 16, 16:19 UTCJul 16, 17:00 UTC40m
2026-07-16 UAL1757 - Jul 16, 06:10 UTCJul 16, 06:35 UTC25m
2026-07-15 UAL2111 - Jul 15, 23:30 UTCJul 16, 04:20 UTC4h 50m
2026-07-15 UAL1384 - Jul 15, 16:35 UTCJul 15, 21:25 UTC4h 50m
2026-07-15 UAL1384 SFO → LIH Jul 15, 16:29 UTCJul 15, 21:36 UTC5h 7m
2026-07-14 UAL477 - Jul 14, 22:10 UTCJul 15, 02:35 UTC4h 24m

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 N37367 page for operator, model, and routing details .

Mode-S A4423A frequently asked

What is Mode-S code A4423A?
A4423A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37367.
Where is Mode-S A4423A registered?
Mode-S code A4423A 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 A4423A broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 20:25 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A4423A, octal 51041072, decimal 10,764,858.
What flights does A4423A operate?
Mode-S A4423A has broadcast 20 distinct callsigns, including UAL1009, UAL474, UAL359, UAL2007, UAL1352.