Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A1C7E4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N2136U · BOEING 777-300ER · operated by UNITED AIRLINES INC

Hex
A1C7E4
Octal
50343744
Decimal
10,602,468
Country
US
Tail
N2136U
Type
B77W
No current signal · last broadcast 2h ago
Flights observed
221
Distinct callsigns
20
Country
US
Last broadcast
2h ago

Last known position

Most recent position reported by Mode-S A1C7E4.

Country allocation

The ICAO 24-bit address A1C7E4 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
UAL857 - 13 2026-06-17
UAL989 - 12 2026-06-30
UAL869 - 12 2026-06-21
UAL858 - 11 2026-06-19
UAL988 - 10 2026-06-29
UAL190 - 10 2026-06-23
UAL871 - 9 2026-07-08
UAL878 - 8 2026-06-21
UAL951 United Airlines 7 2026-06-30
UAL950 - 7 2026-06-29
UAL872 - 7 2026-07-10
UAL862 - 7 2026-07-08
UAL435 - 7 2026-06-25
UAL189 - 7 2026-06-22
UAL877 - 6 2026-07-07
UAL40 United Airlines 6 2026-05-16
UAL1777 United Airlines 6 2026-04-28
UAL838 - 5 2026-07-06
UAL837 - 5 2026-07-10
UAL79 - 5 2026-07-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 UAL79 EWR → NRT Jul 13, 16:02 UTCJul 14, 05:16 UTC13h 14m
2026-07-13 UAL79 - Jul 13, 16:00 UTCJul 13, 23:35 UTC7h 35m
2026-07-13 UAL2416 - Jul 13, 07:15 UTCJul 13, 12:05 UTC4h 50m
2026-07-12 UAL1960 EWR → SFO Jul 12, 16:25 UTCJul 12, 21:20 UTC4h 55m
2026-07-11 UAL78 - Jul 11, 10:05 UTCJul 11, 22:20 UTC12h 15m
2026-07-10 UAL837 SFO → NRT Jul 10, 21:57 UTCJul 11, 07:31 UTC9h 34m
2026-07-10 UAL837 - Jul 10, 21:50 UTCJul 10, 22:15 UTC25m
2026-07-10 UAL872 TPE → SFO Jul 10, 02:23 UTCJul 10, 13:14 UTC10h 51m
2026-07-10 UAL872 - Jul 10, 02:00 UTCJul 10, 13:20 UTC11h 20m
2026-07-08 UAL871 SFO → TPE Jul 8, 23:48 UTCJul 9, 12:05 UTC12h 17m
2026-07-08 UAL871 - Jul 8, 23:40 UTCJul 9, 00:10 UTC30m
2026-07-08 UAL862 - Jul 8, 04:00 UTCJul 8, 16:05 UTC12h 5m
2026-07-07 UAL877 - Jul 7, 07:35 UTCJul 7, 20:55 UTC13h 20m
2026-07-06 UAL838 - Jul 6, 08:15 UTCJul 6, 17:00 UTC8h 45m
2026-07-05 UAL79 EWR → NRT Jul 5, 15:55 UTCJul 6, 04:15 UTC12h 20m
2026-07-05 UAL2416 SFO → EWR Jul 5, 07:15 UTCJul 5, 11:55 UTC4h 40m
2026-07-04 UAL838 - Jul 4, 12:35 UTCJul 4, 21:25 UTC8h 50m
2026-07-04 UAL79 SFO → NRT Jul 4, 00:10 UTCJul 4, 09:55 UTC9h 45m
2026-07-03 UAL79 - Jul 3, 16:20 UTCJul 3, 21:35 UTC5h 15m
2026-07-03 UAL2416 SFO → EWR Jul 3, 08:10 UTCJul 3, 12:55 UTC4h 45m
2026-07-02 UAL1844 - Jul 2, 00:30 UTCJul 2, 05:40 UTC5h 10m
2026-07-01 UAL43 - Jul 1, 10:05 UTCJul 1, 18:15 UTC8h 10m
2026-06-30 UAL989 - Jun 30, 22:05 UTCJul 1, 05:00 UTC6h 55m
2026-06-30 UAL989 IAD → FRA Jun 30, 22:03 UTCJul 1, 05:08 UTC7h 5m
2026-06-30 UAL951 BRU → IAD Jun 30, 10:44 UTCJun 30, 18:18 UTC7h 34m
2026-06-30 UAL951 BRU → IAD Jun 30, 10:45 UTCJun 30, 12:05 UTC1h 20m
2026-06-29 UAL950 IAD → BRU Jun 29, 22:30 UTCJun 30, 05:10 UTC6h 40m
2026-06-29 UAL950 IAD → BRU Jun 29, 22:23 UTCJun 30, 05:05 UTC6h 42m
2026-06-29 UAL988 - Jun 29, 11:10 UTCJun 29, 19:20 UTC8h 10m
2026-06-29 UAL988 FRA → IAD Jun 29, 11:14 UTCJun 29, 19:20 UTC8h 6m
2026-06-28 UAL989 IAD → FRA Jun 28, 22:34 UTCJun 29, 05:34 UTC7h 0m
2026-06-28 UAL951 BRU → IAD Jun 28, 11:29 UTCJun 28, 13:00 UTC1h 30m
2026-06-28 UAL951 BRU → IAD Jun 28, 11:24 UTCJun 28, 19:22 UTC7h 58m
2026-06-28 UAL951 BRU → IAD Jun 28, 11:24 UTCJun 28, 19:13 UTC7h 49m
2026-06-27 UAL950 - Jun 27, 22:09 UTCJun 27, 23:14 UTC1h 5m
2026-06-27 UAL950 IAD → BRU Jun 27, 22:03 UTCJun 28, 05:09 UTC7h 6m
2026-06-27 UAL988 FRA → IAD Jun 27, 11:20 UTCJun 27, 19:19 UTC8h 0m
2026-06-27 UAL988 FRA → IAD Jun 27, 11:19 UTCJun 27, 19:14 UTC7h 55m
2026-06-26 UAL989 IAD → FRA Jun 26, 22:10 UTCJun 27, 05:33 UTC7h 23m
2026-06-26 UAL989 - Jun 26, 22:25 UTCJun 27, 04:59 UTC6h 35m
2026-06-26 UAL988 - Jun 26, 11:20 UTCJun 26, 19:35 UTC8h 15m
2026-06-26 UAL42 - Jun 26, 00:05 UTCJun 26, 06:50 UTC6h 45m
2026-06-25 UAL435 - Jun 25, 15:50 UTCJun 25, 20:34 UTC4h 45m
2026-06-25 UAL1346 - Jun 25, 08:20 UTCJun 25, 12:40 UTC4h 20m
2026-06-25 UAL1346 HNL → SFO Jun 25, 08:24 UTCJun 25, 12:34 UTC4h 10m
2026-06-25 UAL200 - Jun 25, 03:44 UTCJun 25, 04:10 UTC25m
2026-06-24 UAL201 - Jun 24, 00:55 UTCJun 24, 01:04 UTC10m
2026-06-23 UAL1175 - Jun 23, 20:59 UTCJun 23, 21:20 UTC20m
2026-06-23 UAL1175 - Jun 23, 16:39 UTCJun 23, 17:04 UTC25m
2026-06-23 UAL190 MNL → SFO Jun 23, 01:01 UTCJun 23, 13:10 UTC12h 9m

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 N2136U page for operator, model, and routing details .

Mode-S A1C7E4 frequently asked

What is Mode-S code A1C7E4?
A1C7E4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N2136U.
Where is Mode-S A1C7E4 registered?
Mode-S code A1C7E4 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 A1C7E4 broadcasting right now?
No active broadcast right now. Last signal was 2h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1C7E4, octal 50343744, decimal 10,602,468.
What flights does A1C7E4 operate?
Mode-S A1C7E4 has broadcast 20 distinct callsigns, including UAL857, UAL989, UAL869, UAL858, UAL988.