Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A44544

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37419 · BOEING 737-900 · operated by UNITED AIRLINES INC

Hex
A44544
Octal
51042504
Decimal
10,765,636
Country
US
Tail
N37419
Type
B739
No current signal · last broadcast Jul 26, 23:00 UTC
Flights observed
485
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Last known position

Most recent position reported by Mode-S A44544.

Country allocation

The ICAO 24-bit address A44544 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
UAL2425 - 6 2026-06-27
UAL2331 - 5 2026-07-09
UAL2239 - 5 2026-06-21
UAL2629 - 4 2026-07-11
UAL2431 United Airlines 4 2026-07-25
UAL2347 - 4 2026-07-17
UAL2322 - 4 2026-07-17
UAL2209 - 4 2026-07-17
UAL2156 United Airlines 4 2026-04-18
UAL1850 United Airlines 4 2026-05-26
UAL1126 - 4 2026-06-21
UAL773 - 3 2026-06-21
UAL644 - 3 2026-06-22
UAL577 United Airlines 3 2026-05-17
UAL320 - 3 2026-07-01
UAL293 United Airlines 3 2026-05-24
UAL279 United Airlines 3 2026-05-31
UAL2784 United Airlines 3 2026-05-28
UAL2240 United Airlines 3 2026-06-10
UAL2138 United Airlines 3 2026-07-22

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2173 MYR → ORD Jul 26, 21:25 UTCJul 26, 22:50 UTC1h 25m
2026-07-26 UAL2255 MSO → DEN Jul 26, 17:50 UTCJul 26, 19:20 UTC1h 30m
2026-07-26 UAL703 DEN → BIL Jul 26, 14:20 UTCJul 26, 16:10 UTC1h 50m
2026-07-26 UAL2179 LGA → ORD Jul 26, 05:55 UTCJul 26, 06:55 UTC1h 1m
2026-07-26 UAL2179 LGA → ORD Jul 26, 06:01 UTCJul 26, 06:51 UTC50m
2026-07-25 UAL1575 MSP → EWR Jul 25, 23:05 UTCJul 26, 04:20 UTC5h 15m
2026-07-25 UAL2431 FLL → EWR Jul 25, 16:15 UTCJul 25, 21:00 UTC4h 45m
2026-07-25 UAL717 MFR → SFO Jul 25, 13:10 UTCJul 25, 14:10 UTC1h 0m
2026-07-25 UAL548 BWI → DEN Jul 25, 05:00 UTCJul 25, 05:45 UTC45m
2026-07-25 UAL2681 DEN → SFO Jul 25, 02:25 UTCJul 25, 03:25 UTC1h 0m
2026-07-24 UAL1743 IAH → CVG Jul 24, 21:55 UTCJul 25, 00:45 UTC2h 50m
2026-07-24 UAL334 BOS → EWR Jul 24, 19:40 UTCJul 24, 20:15 UTC35m
2026-07-24 UAL1859 IAD → BTV Jul 24, 17:40 UTCJul 24, 18:10 UTC30m
2026-07-24 UAL1318 EWR → MSY Jul 24, 13:20 UTCJul 24, 15:45 UTC2h 25m
2026-07-24 UAL2432 SFO → LAS Jul 24, 03:15 UTCJul 24, 05:20 UTC2h 5m
2026-07-23 UAL588 ATL → EWR Jul 23, 23:40 UTCJul 24, 01:35 UTC1h 55m
2026-07-23 UAL1520 MCO → DEN Jul 23, 17:00 UTCJul 23, 20:15 UTC3h 15m
2026-07-23 UAL2321 SFO → EWR Jul 23, 12:05 UTCJul 23, 15:20 UTC3h 15m
2026-07-23 UAL2019 OGG → SFO Jul 23, 03:15 UTCJul 23, 05:15 UTC2h 0m
2026-07-22 UAL1334 EWR → PBI Jul 22, 21:30 UTCJul 23, 01:20 UTC3h 50m
2026-07-22 UAL2138 ORD → EWR Jul 22, 18:15 UTCJul 22, 19:05 UTC50m
2026-07-22 UAL1297 LAS → EWR Jul 22, 16:00 UTCJul 22, 16:30 UTC30m
2026-07-22 UAL656 - Jul 22, 13:15 UTCJul 22, 13:50 UTC35m
2026-07-22 UAL2311 IAH → RNO Jul 22, 00:35 UTCJul 22, 03:30 UTC2h 55m
2026-07-21 UAL1496 DEN → MIA Jul 21, 16:45 UTCJul 21, 20:20 UTC3h 35m
2026-07-21 UAL557 - Jul 21, 13:35 UTCJul 21, 14:45 UTC1h 10m
2026-07-21 UAL1417 DEN → RDU Jul 21, 02:15 UTCJul 21, 03:25 UTC1h 10m
2026-07-20 UAL2288 IAH → LAS Jul 20, 21:25 UTCJul 21, 00:30 UTC3h 4m
2026-07-20 UAL2269 - Jul 20, 16:20 UTCJul 20, 19:20 UTC3h 0m
2026-07-20 UAL1232 EWR → ORD Jul 20, 13:30 UTCJul 20, 14:25 UTC55m
2026-07-20 UAL2769 DEN → SLC Jul 20, 01:55 UTCJul 20, 02:55 UTC1h 0m
2026-07-19 UAL1596 PDX → SFO Jul 19, 21:35 UTCJul 19, 23:45 UTC2h 10m
2026-07-19 UAL8161 DEN → SFO Jul 19, 17:45 UTCJul 19, 19:55 UTC2h 10m
2026-07-19 UAL728 - Jul 19, 13:15 UTCJul 19, 15:40 UTC2h 25m
2026-07-19 UAL1843 DEN → CMH Jul 19, 00:10 UTCJul 19, 02:30 UTC2h 20m
2026-07-19 UAL1843 DEN → CMH Jul 19, 00:03 UTCJul 19, 02:29 UTC2h 26m
2026-07-18 UAL1662 SLC → DEN Jul 18, 20:45 UTCJul 18, 21:45 UTC1h 0m
2026-07-18 UAL1963 DEN → SLC Jul 18, 18:00 UTCJul 18, 19:00 UTC1h 0m
2026-07-18 UAL2648 - Jul 18, 14:00 UTCJul 18, 16:05 UTC2h 5m
2026-07-18 UAL2648 GRR → DEN Jul 18, 13:46 UTCJul 18, 16:05 UTC2h 19m
2026-07-18 UAL2121 IAH → ORD Jul 18, 00:35 UTCJul 18, 02:45 UTC2h 10m
2026-07-17 UAL1412 TPA → EWR Jul 17, 20:15 UTCJul 17, 22:25 UTC2h 10m
2026-07-17 UAL2322 - Jul 17, 17:55 UTCJul 17, 18:40 UTC45m
2026-07-17 UAL2322 SFO → MFR Jul 17, 18:03 UTCJul 17, 18:39 UTC36m
2026-07-17 UAL2209 - Jul 17, 14:55 UTCJul 17, 16:29 UTC1h 35m
2026-07-17 UAL2347 - Jul 17, 03:25 UTCJul 17, 05:20 UTC1h 55m
2026-07-16 UAL1334 ORD → SFO Jul 16, 21:10 UTCJul 17, 01:09 UTC4h 0m
2026-07-16 UAL2138 - Jul 16, 18:15 UTCJul 16, 18:59 UTC45m
2026-07-16 UAL2138 GRR → ORD Jul 16, 18:13 UTCJul 16, 18:30 UTC17m
2026-07-16 UAL1297 - Jul 16, 16:40 UTCJul 16, 17:05 UTC25m

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 N37419 page for operator, model, and routing details .

Mode-S A44544 frequently asked

What is Mode-S code A44544?
A44544 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37419.
Where is Mode-S A44544 registered?
Mode-S code A44544 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 A44544 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 23:00 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A44544, octal 51042504, decimal 10,765,636.
What flights does A44544 operate?
Mode-S A44544 has broadcast 20 distinct callsigns, including UAL2425, UAL2331, UAL2239, UAL2629, UAL2431.