Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A3EF1B

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N35236 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
A3EF1B
Octal
50767433
Decimal
10,743,579
Country
US
Tail
N35236
Type
B738
No current signal · last broadcast 28m ago
Flights observed
217
Distinct callsigns
20
Country
US
Last broadcast
28m ago

Last known position

Most recent position reported by Mode-S A3EF1B.

Country allocation

The ICAO 24-bit address A3EF1B 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
UAL2745 United Airlines 4 2026-05-26
UAL1787 United Airlines 4 2026-05-23
UAL1315 United Airlines 4 2026-06-01
UAL1022 United Airlines 4 2026-06-01
UAL345 United Airlines 3 2026-05-21
UAL2456 - 3 2026-06-13
UAL2323 United Airlines 3 2026-06-01
UAL2093 United Airlines 3 2026-05-07
UAL1578 United Airlines 3 2026-05-18
UAL1481 United Airlines 3 2026-06-05
UAL1423 United Airlines 3 2026-05-19
UAL1318 United Airlines 3 2026-06-12
UAL1191 United Airlines 3 2026-05-31
UAL1003 United Airlines 3 2026-05-12
UAL8201 United Airlines 2 2026-05-17
UAL8190 United Airlines 2 2026-06-07
UAL741 United Airlines 2 2026-06-06
UAL719 United Airlines 2 2026-05-09
UAL685 - 2 2026-06-13
UAL609 United Airlines 2 2026-05-04

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-16 UAL1973 SFO → YVR Jun 16, 04:35 UTCJun 16, 06:25 UTC1h 50m
2026-06-15 UAL1881 SFO → SJD Jun 15, 18:15 UTCJun 16, 01:00 UTC6h 45m
2026-06-15 UAL540 - Jun 15, 10:45 UTCJun 15, 15:59 UTC5h 15m
2026-06-14 UAL2498 IAH → EWR Jun 14, 23:50 UTCJun 15, 02:04 UTC2h 15m
2026-06-14 UAL2263 EWR → FLL Jun 14, 19:15 UTCJun 14, 20:45 UTC1h 30m
2026-06-14 UAL2263 EWR → FLL Jun 14, 18:41 UTCJun 14, 20:38 UTC1h 57m
2026-06-14 UAL1622 IAH → PVR Jun 14, 15:25 UTCJun 14, 16:35 UTC1h 10m
2026-06-14 UAL1622 IAH → PVR Jun 14, 15:30 UTCJun 14, 17:26 UTC1h 56m
2026-06-14 UAL1114 SFO → ORD Jun 14, 10:40 UTCJun 14, 13:00 UTC2h 20m
2026-06-13 UAL685 - Jun 13, 23:40 UTCJun 14, 02:15 UTC2h 35m
2026-06-13 UAL685 IAH → DTW Jun 13, 23:51 UTCJun 14, 02:10 UTC2h 19m
2026-06-13 UAL2456 - Jun 13, 20:00 UTCJun 13, 21:55 UTC1h 55m
2026-06-13 UAL2456 MCO → IAH Jun 13, 19:59 UTCJun 13, 21:51 UTC1h 52m
2026-06-13 UAL1488 IAD → BTV Jun 13, 16:20 UTCJun 13, 18:10 UTC1h 50m
2026-06-13 UAL544 LAX → SFO Jun 13, 12:40 UTCJun 13, 14:50 UTC2h 10m
2026-06-13 UAL544 LAX → SFO Jun 13, 12:39 UTCJun 13, 14:50 UTC2h 11m
2026-06-13 UAL2753 LAX → SFO Jun 13, 08:40 UTCJun 13, 11:10 UTC2h 30m
2026-06-13 UAL8133 SFO → DEN Jun 13, 01:55 UTCJun 13, 04:40 UTC2h 45m
2026-06-12 UAL1867 - Jun 12, 22:35 UTCJun 12, 23:10 UTC35m
2026-06-12 UAL1919 IAH → CZM Jun 12, 18:20 UTCJun 12, 18:35 UTC15m
2026-06-12 UAL1318 EWR → MSY Jun 12, 13:25 UTCJun 12, 15:30 UTC2h 5m
2026-06-12 UAL2432 SFO → LAS Jun 12, 05:00 UTCJun 12, 07:15 UTC2h 15m
2026-06-12 UAL349 CZM → ORD Jun 12, 00:40 UTCJun 12, 03:30 UTC2h 50m
2026-06-11 UAL2855 EWR → SFO Jun 11, 22:15 UTCJun 11, 23:25 UTC1h 10m
2026-06-11 UAL2619 DEN → MSP Jun 11, 19:00 UTCJun 11, 20:35 UTC1h 35m
2026-06-11 UAL2374 ORD → CLE Jun 11, 14:50 UTCJun 11, 16:25 UTC1h 35m
2026-06-10 UAL1712 LAX → SFO Jun 10, 17:25 UTCJun 10, 20:40 UTC3h 15m
2026-06-10 UAL539 PHL → SFO Jun 10, 12:40 UTCJun 10, 14:40 UTC2h 0m
2026-06-10 UAL539 PHL → SFO Jun 10, 12:48 UTCJun 10, 14:35 UTC1h 47m
2026-06-10 UAL2094 IAH → LGA Jun 10, 05:50 UTCJun 10, 08:45 UTC2h 55m
2026-06-10 UAL2094 IAH → LGA Jun 10, 05:50 UTCJun 10, 09:05 UTC3h 15m
2026-06-10 UAL2262 LAS → SFO Jun 10, 02:35 UTCJun 10, 04:00 UTC1h 25m
2026-06-09 UAL1243 PVR → SFO Jun 9, 16:45 UTCJun 9, 23:30 UTC6h 45m
2026-06-09 UAL1212 SFO → PVR Jun 9, 15:40 UTCJun 9, 15:50 UTC10m
2026-06-09 UAL1896 SEA → SFO Jun 9, 12:25 UTCJun 9, 13:45 UTC1h 20m
2026-06-08 UAL1525 RDU → EWR Jun 8, 19:35 UTCJun 8, 23:30 UTC3h 55m
2026-06-08 UAL1845 BWI → LAX Jun 8, 13:45 UTCJun 8, 17:05 UTC3h 20m
2026-06-08 UAL2770 MSY → ORD Jun 8, 03:13 UTCJun 8, 06:44 UTC3h 31m
2026-06-08 UAL2770 MSY → ORD Jun 8, 03:00 UTCJun 8, 06:40 UTC3h 40m
2026-06-07 UAL329 SRQ → EWR Jun 7, 23:05 UTCJun 8, 01:00 UTC1h 55m
2026-06-07 UAL329 SRQ → EWR Jun 7, 23:12 UTCJun 8, 00:56 UTC1h 44m
2026-06-07 UAL690 SEA → SFO Jun 7, 16:15 UTCJun 7, 19:30 UTC3h 15m
2026-06-07 UAL550 DEN → DFW Jun 7, 12:10 UTCJun 7, 14:10 UTC2h 0m
2026-06-07 UAL8190 ORD → SFO Jun 7, 02:32 UTCJun 7, 05:17 UTC2h 45m
2026-06-07 UAL8190 ORD → SFO Jun 7, 02:14 UTCJun 7, 04:45 UTC2h 30m
2026-06-06 UAL766 SJD → ORD Jun 6, 15:54 UTCJun 6, 23:00 UTC7h 5m
2026-06-06 UAL2096 LAX → EWR Jun 6, 13:15 UTCJun 6, 14:20 UTC1h 5m
2026-06-06 UAL1496 FLL → EWR Jun 6, 04:25 UTCJun 6, 05:25 UTC1h 0m
2026-06-06 UAL741 LAS → EWR Jun 6, 00:10 UTCJun 6, 01:54 UTC1h 44m
2026-06-05 UAL741 LAS → EWR Jun 5, 20:10 UTCJun 6, 02:00 UTC5h 50m

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 N35236 page for operator, model, and routing details .

Mode-S A3EF1B frequently asked

What is Mode-S code A3EF1B?
A3EF1B is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N35236.
Where is Mode-S A3EF1B registered?
Mode-S code A3EF1B 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 A3EF1B broadcasting right now?
No active broadcast right now. Last signal was 28m ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A3EF1B, octal 50767433, decimal 10,743,579.
What flights does A3EF1B operate?
Mode-S A3EF1B has broadcast 20 distinct callsigns, including UAL2745, UAL1787, UAL1315, UAL1022, UAL345.