Apparatus

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sensors Mode-S transponder

A44520

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37408 · BOEING 737-900 · operated by UNITED AIRLINES INC

Hex
A44520
Octal
51042440
Decimal
10,765,600
Country
US
Tail
N37408
Type
B739
No current signal · last broadcast Jul 26, 21:55 UTC
Flights observed
366
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:55 UTC

Last known position

Most recent position reported by Mode-S A44520.

Country allocation

The ICAO 24-bit address A44520 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
UAL2406 United Airlines 14 2026-07-21
UAL1927 United Airlines 11 2026-07-20
UAL740 United Airlines 10 2026-07-20
UAL2662 United Airlines 10 2026-07-05
UAL1950 United Airlines 10 2026-07-26
UAL2310 - 9 2026-07-21
UAL1872 - 9 2026-07-05
UAL496 - 7 2026-06-21
UAL2449 United Airlines 7 2026-07-25
UAL2215 - 7 2026-06-21
UAL2124 - 7 2026-07-01
UAL1971 United Airlines 7 2026-07-24
UAL1127 - 7 2026-07-08
UAL678 United Airlines 6 2026-07-26
UAL2293 - 6 2026-06-25
UAL2275 - 6 2026-06-24
UAL2250 United Airlines 6 2026-07-25
UAL1571 - 6 2026-07-08
UAL1563 - 6 2026-06-29
UAL378 United Airlines 5 2026-05-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1949 ORD → DCA Jul 26, 20:25 UTCJul 26, 21:55 UTC1h 30m
2026-07-26 UAL2773 HNL → ORD Jul 26, 15:25 UTCJul 26, 18:40 UTC3h 15m
2026-07-26 UAL2773 HNL → ORD Jul 26, 15:28 UTCJul 26, 18:39 UTC3h 11m
2026-07-26 UAL678 LAS → SFO Jul 26, 13:10 UTCJul 26, 14:00 UTC50m
2026-07-26 UAL1950 KOA → SFO Jul 26, 01:50 UTCJul 26, 02:35 UTC45m
2026-07-25 UAL1444 SFO → IAH Jul 25, 21:45 UTCJul 26, 00:10 UTC2h 25m
2026-07-25 UAL315 FLL → IAD Jul 25, 17:10 UTCJul 25, 19:40 UTC2h 30m
2026-07-25 UAL2827 IAH → ORD Jul 25, 15:00 UTCJul 25, 15:40 UTC40m
2026-07-25 UAL2827 IAH → ORD Jul 25, 14:50 UTCJul 25, 15:36 UTC46m
2026-07-25 UAL2250 IAH → SAT Jul 25, 12:30 UTCJul 25, 13:10 UTC40m
2026-07-25 UAL2449 SJC → IAH Jul 25, 03:05 UTCJul 25, 05:45 UTC2h 40m
2026-07-24 UAL1971 EWR → SAT Jul 24, 19:45 UTCJul 24, 22:25 UTC2h 40m
2026-07-24 UAL2812 ORD → EWR Jul 24, 15:45 UTCJul 24, 18:00 UTC2h 15m
2026-07-24 UAL8178 ORD → JAC Jul 24, 01:40 UTCJul 24, 03:50 UTC2h 10m
2026-07-23 UAL1609 IAH → SFO Jul 23, 22:45 UTCJul 23, 23:35 UTC50m
2026-07-23 UAL1388 - Jul 23, 19:55 UTCJul 23, 20:40 UTC45m
2026-07-23 UAL2253 RDU → IAD Jul 23, 17:20 UTCJul 23, 18:10 UTC50m
2026-07-23 UAL575 BOS → ORD Jul 23, 14:55 UTCJul 23, 15:50 UTC55m
2026-07-23 UAL575 BOS → ORD Jul 23, 15:05 UTCJul 23, 15:49 UTC44m
2026-07-23 UAL1859 IAD → BTV Jul 23, 10:25 UTCJul 23, 12:40 UTC2h 15m
2026-07-23 UAL1591 DEN → EWR Jul 23, 01:25 UTCJul 23, 03:45 UTC2h 20m
2026-07-23 UAL1591 DEN → EWR Jul 23, 01:23 UTCJul 23, 03:45 UTC2h 22m
2026-07-22 UAL2833 EWR → IAH Jul 22, 21:30 UTCJul 22, 23:50 UTC2h 20m
2026-07-22 UAL2833 EWR → IAH Jul 22, 21:34 UTCJul 22, 23:46 UTC2h 12m
2026-07-22 UAL8161 - Jul 22, 18:05 UTCJul 22, 20:15 UTC2h 10m
2026-07-22 UAL8161 IAH → RSW Jul 22, 18:17 UTCJul 22, 20:04 UTC1h 47m
2026-07-22 UAL1318 EWR → MSY Jul 22, 13:30 UTCJul 22, 15:40 UTC2h 10m
2026-07-21 UAL1507 HAV → IAH Jul 21, 22:25 UTCJul 22, 00:35 UTC2h 10m
2026-07-21 UAL2406 LAX → SFO Jul 21, 18:20 UTCJul 21, 20:20 UTC2h 0m
2026-07-21 UAL2310 - Jul 21, 14:45 UTCJul 21, 16:45 UTC2h 0m
2026-07-21 UAL678 LAS → SFO Jul 21, 12:10 UTCJul 21, 13:10 UTC1h 0m
2026-07-21 UAL1950 KOA → SFO Jul 21, 02:00 UTCJul 21, 02:45 UTC45m
2026-07-21 UAL1950 KOA → SFO Jul 21, 01:50 UTCJul 21, 02:45 UTC55m
2026-07-20 UAL1927 ORD → EWR Jul 20, 20:15 UTCJul 21, 00:05 UTC3h 50m
2026-07-20 UAL740 SEA → DEN Jul 20, 14:55 UTCJul 20, 18:30 UTC3h 35m
2026-07-20 UAL2812 - Jul 20, 00:35 UTCJul 20, 02:50 UTC2h 15m
2026-07-20 UAL2812 PHX → IAH Jul 20, 00:33 UTCJul 20, 02:51 UTC2h 18m
2026-07-19 UAL8193 YYG → YUL Jul 19, 01:30 UTCJul 19, 03:40 UTC2h 10m
2026-07-18 UAL497 CVG → DEN Jul 18, 19:20 UTCJul 18, 22:00 UTC2h 40m
2026-07-18 UAL1898 - Jul 18, 15:10 UTCJul 18, 17:35 UTC2h 25m
2026-07-18 UAL1898 IAH → SLC Jul 18, 15:10 UTCJul 18, 17:36 UTC2h 26m
2026-07-18 UAL468 SFO → LAS Jul 18, 11:25 UTCJul 18, 13:25 UTC2h 0m
2026-07-08 UAL1571 - Jul 8, 22:50 UTCJul 9, 00:50 UTC2h 0m
2026-07-08 UAL2406 - Jul 8, 18:55 UTCJul 8, 20:50 UTC1h 55m
2026-07-08 UAL2310 - Jul 8, 15:25 UTCJul 8, 17:20 UTC1h 55m
2026-07-08 UAL1127 OKC → IAH Jul 8, 12:57 UTCJul 8, 13:54 UTC57m
2026-07-08 UAL1127 - Jul 8, 12:55 UTCJul 8, 13:50 UTC55m
2026-07-08 UAL2304 SFO → PSP Jul 8, 01:50 UTCJul 8, 03:05 UTC1h 15m
2026-07-07 UAL1444 - Jul 7, 21:20 UTCJul 8, 00:05 UTC2h 45m
2026-07-07 UAL315 FLL → IAD Jul 7, 17:20 UTCJul 7, 19:40 UTC2h 20m

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 N37408 page for operator, model, and routing details .

Mode-S A44520 frequently asked

What is Mode-S code A44520?
A44520 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37408.
Where is Mode-S A44520 registered?
Mode-S code A44520 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 A44520 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:55 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A44520, octal 51042440, decimal 10,765,600.
What flights does A44520 operate?
Mode-S A44520 has broadcast 20 distinct callsigns, including UAL2406, UAL1927, UAL740, UAL2662, UAL1950.