Apparatus

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sensors Mode-S transponder

A3CF4F

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N34455 · BOEING 737-900 · operated by UNITED AIRLINES INC

Hex
A3CF4F
Octal
50747517
Decimal
10,735,439
Country
US
Tail
N34455
Type
B739
No current signal · last broadcast Jul 26, 19:20 UTC
Flights observed
419
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 19:20 UTC

Last known position

Most recent position reported by Mode-S A3CF4F.

Country allocation

The ICAO 24-bit address A3CF4F 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
UAL1101 - 5 2026-07-20
UAL2184 United Airlines 4 2026-05-19
UAL2175 United Airlines 4 2026-04-15
UAL2016 United Airlines 4 2026-07-26
UAL1677 United Airlines 4 2026-04-18
UAL688 United Airlines 3 2026-05-14
UAL682 - 3 2026-07-06
UAL677 United Airlines 3 2026-06-17
UAL469 - 3 2026-06-21
UAL406T United Airlines 3 2026-04-15
UAL320 - 3 2026-06-21
UAL2737 United Airlines 3 2026-04-21
UAL2646 United Airlines 3 2026-04-14
UAL2486 United Airlines 3 2026-04-17
UAL2425 - 3 2026-06-16
UAL2396 United Airlines 3 2026-05-06
UAL2384 United Airlines 3 2026-04-16
UAL2304 United Airlines 3 2026-07-25
UAL2290 United Airlines 3 2026-05-20
UAL1963 - 3 2026-06-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1737 LAX → AUS Jul 26, 17:05 UTCJul 26, 17:35 UTC30m
2026-07-26 UAL1737 LAX → AUS Jul 26, 17:12 UTCJul 26, 20:09 UTC2h 57m
2026-07-26 UAL2196 AUS → IAH Jul 26, 14:50 UTCJul 26, 15:30 UTC40m
2026-07-26 UAL2016 BDL → ORD Jul 26, 12:45 UTCJul 26, 13:20 UTC35m
2026-07-26 UAL2016 BDL → ORD Jul 26, 12:49 UTCJul 26, 13:15 UTC26m
2026-07-25 UAL497 CVG → DEN Jul 25, 19:10 UTCJul 25, 21:45 UTC2h 35m
2026-07-25 UAL497 CVG → DEN Jul 25, 19:18 UTCJul 25, 21:42 UTC2h 24m
2026-07-25 UAL1898 DEN → ORD Jul 25, 15:10 UTCJul 25, 17:50 UTC2h 40m
2026-07-25 UAL1127 ORD → SFO Jul 25, 12:32 UTCJul 25, 13:23 UTC51m
2026-07-25 UAL2304 SFO → PSP Jul 25, 01:45 UTCJul 25, 02:45 UTC1h 0m
2026-07-24 UAL2263 EWR → FLL Jul 24, 19:10 UTCJul 24, 20:35 UTC1h 25m
2026-07-24 UAL1622 - Jul 24, 15:00 UTCJul 24, 16:05 UTC1h 5m
2026-07-24 UAL1622 IAH → PVR Jul 24, 14:55 UTCJul 24, 16:51 UTC1h 56m
2026-07-23 UAL2457 RTB → IAH Jul 23, 18:46 UTCJul 23, 21:10 UTC2h 24m
2026-07-23 UAL2043 - Jul 23, 14:55 UTCJul 23, 21:10 UTC6h 15m
2026-07-23 UAL3751 LGB → ORD Jul 23, 07:35 UTCJul 23, 09:30 UTC1h 55m
2026-07-23 UAL3777 MDW → MKC Jul 23, 05:05 UTCJul 23, 06:45 UTC1h 40m
2026-07-23 UAL3777 MDW → MKC Jul 23, 05:05 UTCJul 23, 06:36 UTC1h 31m
2026-07-23 UAL3754 LAX → IAD Jul 23, 01:20 UTCJul 23, 02:05 UTC45m
2026-07-22 UAL1516 LIR → IAH Jul 22, 14:55 UTCJul 22, 22:45 UTC7h 50m
2026-07-21 UAL8215 LAX → IAH Jul 21, 23:50 UTCJul 22, 01:40 UTC1h 50m
2026-07-21 UAL496 EWR → SFO Jul 21, 20:05 UTCJul 21, 22:10 UTC2h 5m
2026-07-21 UAL2812 - Jul 21, 16:10 UTCJul 21, 18:25 UTC2h 15m
2026-07-21 UAL3934 FLL → ORD Jul 21, 07:20 UTCJul 21, 08:40 UTC1h 20m
2026-07-21 UAL3934 FLL → ORD Jul 21, 07:11 UTCJul 21, 08:36 UTC1h 25m
2026-07-20 UAL1126 LAS → EWR Jul 20, 19:35 UTCJul 20, 22:40 UTC3h 5m
2026-07-20 UAL1101 DEN → IAD Jul 20, 15:30 UTCJul 20, 18:15 UTC2h 45m
2026-07-20 UAL687 EWR → IAH Jul 20, 13:35 UTCJul 20, 14:15 UTC40m
2026-07-20 UAL1390 LAS → EWR Jul 20, 02:20 UTCJul 20, 02:45 UTC25m
2026-07-19 UAL2012 PTY → EWR Jul 19, 21:00 UTCJul 20, 00:10 UTC3h 10m
2026-07-19 UAL8160 YYZ → DEL Jul 19, 16:35 UTCJul 19, 19:35 UTC3h 0m
2026-07-19 UAL2167 - Jul 19, 12:10 UTCJul 19, 13:45 UTC1h 35m
2026-07-19 UAL2167 TPA → DEN Jul 19, 12:13 UTCJul 19, 15:15 UTC3h 2m
2026-07-19 UAL1961 LAS → IAD Jul 19, 00:40 UTCJul 19, 03:45 UTC3h 5m
2026-07-18 UAL302 - Jul 18, 20:00 UTCJul 18, 22:25 UTC2h 25m
2026-07-18 UAL1915 SAN → SFO Jul 18, 16:05 UTCJul 18, 18:25 UTC2h 20m
2026-07-18 UAL1010 OMA → SFO Jul 18, 12:45 UTCJul 18, 14:40 UTC1h 55m
2026-07-18 UAL2179 LGA → ORD Jul 18, 06:30 UTCJul 18, 07:30 UTC1h 0m
2026-07-17 UAL1174 SJD → SFO Jul 17, 22:46 UTCJul 18, 01:06 UTC2h 20m
2026-07-17 UAL1881 - Jul 17, 18:50 UTCJul 18, 01:10 UTC6h 20m
2026-07-17 UAL2322 YVR → SFO Jul 17, 14:44 UTCJul 17, 16:55 UTC2h 10m
2026-07-17 UAL2191 - Jul 17, 02:34 UTCJul 17, 04:49 UTC2h 15m
2026-07-17 UAL2191 - Jul 17, 02:44 UTCJul 17, 04:41 UTC1h 57m
2026-07-16 UAL1743 - Jul 16, 22:00 UTCJul 17, 00:55 UTC2h 55m
2026-07-16 UAL1743 IAH → LAX Jul 16, 22:01 UTCJul 17, 00:48 UTC2h 47m
2026-07-16 UAL334 - Jul 16, 19:45 UTCJul 16, 20:25 UTC40m
2026-07-16 UAL1859 - Jul 16, 17:25 UTCJul 16, 17:54 UTC30m
2026-07-15 UAL1426 - Jul 15, 22:30 UTCJul 16, 14:40 UTC16h 10m
2026-07-15 UAL2296 - Jul 15, 19:50 UTCJul 15, 20:50 UTC1h 0m
2026-07-15 UAL2385 - Jul 15, 17:55 UTCJul 15, 18:40 UTC45m

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 N34455 page for operator, model, and routing details .

Mode-S A3CF4F frequently asked

What is Mode-S code A3CF4F?
A3CF4F is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N34455.
Where is Mode-S A3CF4F registered?
Mode-S code A3CF4F 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 A3CF4F broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 19:20 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A3CF4F, octal 50747517, decimal 10,735,439.
What flights does A3CF4F operate?
Mode-S A3CF4F has broadcast 20 distinct callsigns, including UAL1101, UAL2184, UAL2175, UAL2016, UAL1677.