Apparatus

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sensors Mode-S transponder

A441EF

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37342 · BOEING 737 MAX 8 · operated by UMB BANK NA TRUSTEE

Hex
A441EF
Octal
51040757
Decimal
10,764,783
Country
US
Tail
N37342
Type
B38M
No current signal · last broadcast Jul 26, 21:45 UTC
Flights observed
424
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Last known position

Most recent position reported by Mode-S A441EF.

Country allocation

The ICAO 24-bit address A441EF 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
UAL1903 United Airlines 10 2026-07-22
UAL2006 - 6 2026-07-22
UAL368 United Airlines 5 2026-05-01
UAL1219 United Airlines 5 2026-06-15
UAL841 United Airlines 4 2026-07-26
UAL643 - 4 2026-06-28
UAL513 - 4 2026-07-21
UAL394 United Airlines 4 2026-05-31
UAL280 United Airlines 4 2026-06-05
UAL205 - 4 2026-07-17
UAL2021 - 4 2026-07-20
UAL1908 - 4 2026-07-04
UAL1884 United Airlines 4 2026-06-12
UAL1751 - 4 2026-07-10
UAL1678 United Airlines 4 2026-05-01
UAL1368 United Airlines 4 2026-07-20
UAL1194 United Airlines 4 2026-04-17
UAL779 United Airlines 3 2026-06-02
UAL725 United Airlines 3 2026-07-21
UAL649 United Airlines 3 2026-04-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL841 NRT → GUM Jul 26, 21:30 UTCJul 26, 21:45 UTC15m
2026-07-26 UAL1382 PHX → EWR Jul 26, 18:30 UTCJul 26, 19:25 UTC55m
2026-07-26 UAL1355 IAD → EWR Jul 26, 16:10 UTCJul 26, 16:50 UTC40m
2026-07-26 UAL2374 ORD → CLE Jul 26, 12:00 UTCJul 26, 14:25 UTC2h 25m
2026-07-25 UAL2375 PHL → ORD Jul 25, 20:10 UTCJul 25, 23:10 UTC3h 0m
2026-07-25 UAL1413 EWR → PBI Jul 25, 13:55 UTCJul 25, 18:40 UTC4h 45m
2026-07-25 UAL400 AUS → IAD Jul 25, 03:05 UTCJul 25, 08:00 UTC4h 55m
2026-07-24 UAL287 EWR → BOS Jul 24, 19:55 UTCJul 25, 00:00 UTC4h 5m
2026-07-24 UAL2804 IAD → EWR Jul 24, 16:35 UTCJul 24, 17:45 UTC1h 10m
2026-07-24 UAL2804 IAD → EWR Jul 24, 16:29 UTCJul 24, 18:23 UTC1h 54m
2026-07-24 UAL1061 SEA → SFO Jul 24, 12:35 UTCJul 24, 14:10 UTC1h 35m
2026-07-24 UAL1061 SEA → SFO Jul 24, 12:43 UTCJul 24, 13:58 UTC1h 15m
2026-07-24 UAL1627 LAX → EWR Jul 24, 00:10 UTCJul 24, 02:45 UTC2h 35m
2026-07-23 UAL1455 EWR → MIA Jul 23, 19:20 UTCJul 23, 21:30 UTC2h 10m
2026-07-23 UAL1454 IAH → NAS Jul 23, 15:05 UTCJul 23, 17:20 UTC2h 15m
2026-07-22 UAL1903 GUA → IAH Jul 22, 21:55 UTCJul 22, 22:35 UTC40m
2026-07-22 UAL1903 GUA → IAH Jul 22, 20:00 UTCJul 22, 20:10 UTC10m
2026-07-22 UAL2006 - Jul 22, 18:25 UTCJul 22, 18:40 UTC15m
2026-07-22 UAL2006 ORD → GUA Jul 22, 14:47 UTCJul 22, 18:39 UTC3h 52m
2026-07-22 UAL2006 - Jul 22, 14:45 UTCJul 22, 16:50 UTC2h 5m
2026-07-22 UAL723 - Jul 22, 11:10 UTCJul 22, 12:55 UTC1h 45m
2026-07-22 UAL1401 AUS → SFO Jul 22, 03:30 UTCJul 22, 05:05 UTC1h 35m
2026-07-21 UAL2766 HKG → ORD Jul 21, 21:30 UTCJul 22, 01:40 UTC4h 10m
2026-07-21 UAL1415 DEN → SMF Jul 21, 18:00 UTCJul 21, 19:55 UTC1h 55m
2026-07-21 UAL513 - Jul 21, 14:05 UTCJul 21, 16:00 UTC1h 55m
2026-07-21 UAL725 ORD → SFO Jul 21, 02:57 UTCJul 21, 04:46 UTC1h 49m
2026-07-21 UAL725 ORD → SFO Jul 21, 02:55 UTCJul 21, 04:50 UTC1h 55m
2026-07-20 UAL1368 SNA → EWR Jul 20, 19:45 UTCJul 20, 23:30 UTC3h 45m
2026-07-20 UAL1368 SNA → EWR Jul 20, 18:00 UTCJul 20, 18:10 UTC10m
2026-07-20 UAL2021 - Jul 20, 16:30 UTCJul 20, 16:50 UTC20m
2026-07-20 UAL2021 - Jul 20, 13:20 UTCJul 20, 14:55 UTC1h 35m
2026-07-20 UAL1366 IAD → DEN Jul 20, 10:20 UTCJul 20, 11:05 UTC45m
2026-07-19 UAL1699 - Jul 19, 16:20 UTCJul 20, 02:35 UTC10h 15m
2026-07-19 UAL1234 GEG → DEN Jul 19, 12:15 UTCJul 19, 14:00 UTC1h 45m
2026-07-19 UAL778 DEN → BZN Jul 19, 01:45 UTCJul 19, 03:35 UTC1h 50m
2026-07-18 UAL1698 SFO → SLC Jul 18, 20:55 UTCJul 19, 00:00 UTC3h 5m
2026-07-18 UAL1514 - Jul 18, 13:00 UTCJul 18, 15:50 UTC2h 50m
2026-07-18 UAL1514 EWR → PUJ Jul 18, 12:35 UTCJul 18, 16:15 UTC3h 40m
2026-07-18 UAL559 - Jul 18, 04:25 UTCJul 18, 09:40 UTC5h 15m
2026-07-17 UAL205 - Jul 17, 19:45 UTCJul 18, 00:04 UTC4h 20m
2026-07-17 UAL1005 - Jul 17, 05:39 UTCJul 17, 17:20 UTC11h 40m
2026-07-16 UAL2198 - Jul 16, 23:25 UTCJul 17, 01:39 UTC2h 15m
2026-07-16 UAL1238 - Jul 16, 19:40 UTCJul 16, 21:50 UTC2h 10m
2026-07-16 UAL1447 - Jul 16, 14:15 UTCJul 16, 17:25 UTC3h 10m
2026-07-15 UAL1280 - Jul 15, 22:30 UTCJul 16, 01:55 UTC3h 25m
2026-07-15 UAL692 - Jul 15, 16:45 UTCJul 15, 19:50 UTC3h 5m
2026-07-15 UAL1697 - Jul 15, 12:20 UTCJul 15, 15:35 UTC3h 15m
2026-07-15 UAL206 - Jul 15, 06:00 UTCJul 15, 10:15 UTC4h 15m
2026-07-14 UAL268 - Jul 14, 21:40 UTCJul 14, 23:50 UTC2h 9m
2026-07-14 UAL268 EWR → BOG Jul 14, 21:40 UTCJul 15, 02:39 UTC4h 59m

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 N37342 page for operator, model, and routing details .

Mode-S A441EF frequently asked

What is Mode-S code A441EF?
A441EF is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37342.
Where is Mode-S A441EF registered?
Mode-S code A441EF 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 A441EF broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A441EF, octal 51040757, decimal 10,764,783.
What flights does A441EF operate?
Mode-S A441EF has broadcast 20 distinct callsigns, including UAL1903, UAL2006, UAL368, UAL1219, UAL841.