Apparatus

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sensors Mode-S transponder

A445A4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37440 · BOEING 737 MAX 9 · operated by UNITED AIRLINES INC

Hex
A445A4
Octal
51042644
Decimal
10,765,732
Country
US
Tail
N37440
Type
B39M
Broadcasting now · callsign UAL2129 · 28,900 ft
Flights observed
469
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Current position

A445A4 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A445A4 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
UAL693 - 7 2026-07-06
UAL694 United Airlines 6 2026-07-05
UAL2601 United Airlines 5 2026-05-10
UAL2400 - 5 2026-06-19
UAL2219 - 5 2026-07-21
UAL1572 - 5 2026-07-10
UAL277 United Airlines 4 2026-04-15
UAL2738 United Airlines 4 2026-05-10
UAL2373 United Airlines 4 2026-05-22
UAL2372 United Airlines 4 2026-05-23
UAL2229 - 4 2026-07-13
UAL2111 United Airlines 4 2026-04-17
UAL1581 - 4 2026-06-24
UAL1490 United Airlines 4 2026-04-26
UAL1466 United Airlines 4 2026-05-15
UAL1340 United Airlines 4 2026-06-08
UAL1321 - 4 2026-06-30
UAL731 - 3 2026-06-30
UAL684 United Airlines 3 2026-04-17
UAL600 United Airlines 3 2026-07-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL600 EWR → LAS Jul 26, 22:25 UTCJul 26, 23:00 UTC35m
2026-07-26 UAL2825 ORD → PHL Jul 26, 16:30 UTCJul 26, 18:15 UTC1h 45m
2026-07-26 UAL2034 IAH → SFO Jul 26, 12:55 UTCJul 26, 14:25 UTC1h 30m
2026-07-26 UAL1210 EWR → ATL Jul 26, 03:10 UTCJul 26, 06:25 UTC3h 15m
2026-07-26 UAL1210 EWR → ATL Jul 26, 02:59 UTCJul 26, 06:12 UTC3h 13m
2026-07-26 UAL1254 PSP → SFO Jul 26, 00:05 UTCJul 26, 01:50 UTC1h 45m
2026-07-25 UAL2350 SAN → ORD Jul 25, 20:30 UTCJul 25, 22:20 UTC1h 50m
2026-07-25 UAL2153 DEN → SNA Jul 25, 17:50 UTCJul 25, 18:45 UTC55m
2026-07-25 UAL1768 EWR → DEN Jul 25, 12:40 UTCJul 25, 15:55 UTC3h 15m
2026-07-24 UAL1130 SAL → IAH Jul 24, 22:00 UTCJul 25, 00:35 UTC2h 35m
2026-07-24 UAL1290 IAH → SAL Jul 24, 17:55 UTCJul 24, 20:15 UTC2h 20m
2026-07-24 UAL1644 SJU → IAH Jul 24, 13:10 UTCJul 24, 15:25 UTC2h 15m
2026-07-24 UAL1644 SJU → IAH Jul 24, 11:25 UTCJul 24, 11:35 UTC10m
2026-07-24 UAL1497 SFO → IAH Jul 24, 09:00 UTCJul 24, 09:15 UTC15m
2026-07-24 UAL1497 SFO → IAH Jul 24, 05:15 UTCJul 24, 07:25 UTC2h 10m
2026-07-24 UAL1497 SFO → IAH Jul 24, 05:13 UTCJul 24, 09:19 UTC4h 6m
2026-07-23 UAL2002 SFO → IAD Jul 23, 21:45 UTCJul 24, 01:10 UTC3h 25m
2026-07-23 UAL1791 LAS → ORD Jul 23, 18:35 UTCJul 23, 19:30 UTC55m
2026-07-23 UAL325 DEN → BOS Jul 23, 11:10 UTCJul 23, 15:55 UTC4h 45m
2026-07-23 UAL1784 STT → EWR Jul 23, 02:55 UTCJul 23, 03:50 UTC55m
2026-07-22 UAL2489 - Jul 22, 22:15 UTCJul 22, 23:35 UTC1h 20m
2026-07-22 UAL2489 SDQ → EWR Jul 22, 20:02 UTCJul 22, 23:24 UTC3h 22m
2026-07-22 UAL1984 ORD → SFO Jul 22, 14:19 UTCJul 22, 18:20 UTC4h 1m
2026-07-22 UAL1984 ORD → SFO Jul 22, 14:50 UTCJul 22, 16:05 UTC1h 15m
2026-07-21 UAL2359 IAD → BDL Jul 21, 20:55 UTCJul 22, 01:30 UTC4h 35m
2026-07-21 UAL1613 EWR → FLL Jul 21, 10:55 UTCJul 21, 16:25 UTC5h 30m
2026-07-21 UAL2219 - Jul 21, 07:35 UTCJul 21, 08:55 UTC1h 20m
2026-07-21 UAL2219 - Jul 21, 05:10 UTCJul 21, 05:20 UTC10m
2026-07-21 UAL1543 EWR → SJU Jul 21, 03:00 UTCJul 21, 03:20 UTC20m
2026-07-21 UAL1543 EWR → SJU Jul 21, 00:05 UTCJul 21, 00:45 UTC40m
2026-07-20 UAL2677 CLE → DEN Jul 20, 17:00 UTCJul 20, 21:10 UTC4h 10m
2026-07-20 UAL2646 DEN → SJC Jul 20, 11:10 UTCJul 20, 15:30 UTC4h 20m
2026-07-19 UAL2100 SAV → EWR Jul 19, 22:50 UTCJul 20, 03:20 UTC4h 30m
2026-07-19 UAL8107 EWR → SEA Jul 19, 15:45 UTCJul 19, 21:10 UTC5h 25m
2026-07-19 UAL1969 EWR → IAH Jul 19, 11:30 UTCJul 19, 13:45 UTC2h 15m
2026-07-19 UAL1399 - Jul 19, 03:15 UTCJul 19, 05:45 UTC2h 30m
2026-07-17 UAL240 EWR → EWR Jul 17, 23:39 UTCJul 18, 13:50 UTC14h 11m
2026-07-17 UAL1611 - Jul 17, 17:05 UTCJul 17, 19:20 UTC2h 15m
2026-07-17 UAL2444 EWR → FLL Jul 17, 12:55 UTCJul 17, 15:20 UTC2h 25m
2026-07-17 UAL2235 - Jul 17, 00:50 UTCJul 17, 03:25 UTC2h 35m
2026-07-16 UAL246 - Jul 16, 19:25 UTCJul 16, 23:10 UTC3h 45m
2026-07-16 UAL2855 MCO → SFO Jul 16, 12:34 UTCJul 16, 17:30 UTC4h 55m
2026-07-16 UAL1730 - Jul 16, 06:35 UTCJul 16, 11:05 UTC4h 30m
2026-07-15 UAL1213 - Jul 15, 23:50 UTCJul 16, 04:15 UTC4h 25m
2026-07-15 UAL1621 - Jul 15, 17:50 UTCJul 15, 22:20 UTC4h 30m
2026-07-14 UAL600 - Jul 14, 22:30 UTCJul 15, 01:50 UTC3h 19m
2026-07-14 UAL1983 - Jul 14, 16:30 UTCJul 14, 19:05 UTC2h 35m
2026-07-14 UAL1358 ORD → MIA Jul 14, 12:25 UTCJul 14, 15:05 UTC2h 40m
2026-07-14 UAL1640 FAI → ORD Jul 14, 05:00 UTCJul 14, 10:25 UTC5h 25m
2026-07-13 UAL2223 ORD → FAI Jul 13, 21:45 UTCJul 14, 03:40 UTC5h 55m

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 N37440 page for operator, model, and routing details .

Mode-S A445A4 frequently asked

What is Mode-S code A445A4?
A445A4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37440.
Where is Mode-S A445A4 registered?
Mode-S code A445A4 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 A445A4 broadcasting right now?
Yes. Mode-S A445A4 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A445A4, octal 51042644, decimal 10,765,732.
What flights does A445A4 operate?
Mode-S A445A4 has broadcast 20 distinct callsigns, including UAL693, UAL694, UAL2601, UAL2400, UAL2219.