Apparatus

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sensors Mode-S transponder

A4493F

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N37537 · BOEING 737 MAX 9 · operated by UNITED AIRLINES INC

Hex
A4493F
Octal
51044477
Decimal
10,766,655
Country
US
Tail
N37537
Type
B39M
No current signal · last broadcast Jul 26, 21:45 UTC
Flights observed
465
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Last known position

Most recent position reported by Mode-S A4493F.

Country allocation

The ICAO 24-bit address A4493F 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
UAL308 United Airlines 6 2026-07-19
UAL1058 United Airlines 6 2026-06-07
UAL337 - 4 2026-07-17
UAL2182 - 4 2026-07-19
UAL1754 - 4 2026-07-17
UAL1650 United Airlines 4 2026-04-14
UAL1575 United Airlines 4 2026-05-18
UAL1167 United Airlines 4 2026-06-17
UAL1054 United Airlines 4 2026-05-23
UAL1020 United Airlines 4 2026-06-09
UAL709 United Airlines 3 2026-06-05
UAL650 - 3 2026-06-20
UAL505 - 3 2026-06-20
UAL312 - 3 2026-07-20
UAL2661 - 3 2026-07-16
UAL2620 United Airlines 3 2026-04-13
UAL2491 United Airlines 3 2026-06-24
UAL2383 United Airlines 3 2026-04-16
UAL2364 United Airlines 3 2026-05-21
UAL233 - 3 2026-06-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2241 EWR → SAT Jul 26, 17:30 UTCJul 26, 21:45 UTC4h 15m
2026-07-26 UAL2022 SJU → IAD Jul 26, 13:10 UTCJul 26, 15:30 UTC2h 20m
2026-07-26 UAL2022 SJU → IAD Jul 26, 11:30 UTCJul 26, 11:40 UTC10m
2026-07-26 UAL2022 SJU → IAD Jul 26, 11:33 UTCJul 26, 15:30 UTC3h 57m
2026-07-25 UAL2025 IAH → SFO Jul 25, 21:45 UTCJul 26, 01:15 UTC3h 30m
2026-07-25 UAL1071 EWR → ORD Jul 25, 15:10 UTCJul 25, 19:40 UTC4h 30m
2026-07-25 UAL1513 IAH → SFO Jul 25, 01:35 UTCJul 25, 06:30 UTC4h 55m
2026-07-24 UAL1473 SDQ → EWR Jul 24, 22:15 UTCJul 24, 23:25 UTC1h 10m
2026-07-24 UAL2404 EWR → SDQ Jul 24, 14:30 UTCJul 24, 15:25 UTC55m
2026-07-24 UAL2404 EWR → SDQ Jul 24, 14:33 UTCJul 24, 17:47 UTC3h 14m
2026-07-23 UAL2612 EWR → PHX Jul 23, 16:30 UTCJul 23, 18:50 UTC2h 20m
2026-07-23 UAL2612 EWR → PHX Jul 23, 16:27 UTCJul 23, 18:54 UTC2h 27m
2026-07-23 UAL2772 MSY → IAH Jul 23, 12:45 UTCJul 23, 15:15 UTC2h 30m
2026-07-22 UAL1472 SDQ → EWR Jul 22, 19:40 UTCJul 22, 23:00 UTC3h 20m
2026-07-22 UAL1472 SDQ → EWR Jul 22, 19:21 UTCJul 22, 22:57 UTC3h 36m
2026-07-22 UAL1471 EWR → SDQ Jul 22, 14:20 UTCJul 22, 15:40 UTC1h 20m
2026-07-21 UAL274 RDU → EWR Jul 21, 22:40 UTCJul 22, 03:30 UTC4h 50m
2026-07-21 UAL2428 - Jul 21, 19:25 UTCJul 21, 20:25 UTC1h 0m
2026-07-21 UAL1930 IAD → SAN Jul 21, 12:35 UTCJul 21, 17:10 UTC4h 35m
2026-07-21 UAL349 CZM → ORD Jul 21, 06:10 UTCJul 21, 10:35 UTC4h 25m
2026-07-20 UAL2755 LAX → SFO Jul 20, 23:55 UTCJul 21, 02:50 UTC2h 55m
2026-07-20 UAL2755 LAX → SFO Jul 20, 23:54 UTCJul 21, 02:48 UTC2h 54m
2026-07-20 UAL2095 ORD → LAX Jul 20, 19:10 UTCJul 20, 21:50 UTC2h 40m
2026-07-20 UAL2653 RSW → EWR Jul 20, 16:15 UTCJul 20, 17:40 UTC1h 25m
2026-07-20 UAL1878 AUS → ORD Jul 20, 11:45 UTCJul 20, 14:05 UTC2h 20m
2026-07-20 UAL312 ORD → AUS Jul 20, 01:42 UTCJul 20, 03:32 UTC1h 50m
2026-07-20 UAL312 - Jul 20, 01:25 UTCJul 20, 03:35 UTC2h 10m
2026-07-19 UAL308 ATL → EWR Jul 19, 22:00 UTCJul 19, 23:45 UTC1h 45m
2026-07-19 UAL308 ATL → EWR Jul 19, 21:14 UTCJul 19, 23:45 UTC2h 31m
2026-07-19 UAL2182 - Jul 19, 16:55 UTCJul 19, 18:25 UTC1h 30m
2026-07-19 UAL2182 - Jul 19, 12:40 UTCJul 19, 14:50 UTC2h 10m
2026-07-19 UAL1986 - Jul 19, 07:50 UTCJul 19, 10:15 UTC2h 25m
2026-07-18 UAL2024 - Jul 18, 23:25 UTCJul 19, 00:40 UTC1h 15m
2026-07-18 UAL2024 - Jul 18, 21:15 UTCJul 18, 21:25 UTC10m
2026-07-18 UAL2024 SJU → IAD Jul 18, 21:23 UTCJul 19, 00:41 UTC3h 18m
2026-07-18 UAL1192 - Jul 18, 15:45 UTCJul 18, 20:05 UTC4h 20m
2026-07-18 UAL2305 - Jul 18, 00:50 UTCJul 18, 04:15 UTC3h 26m
2026-07-17 UAL1754 MFR → SFO Jul 17, 22:25 UTCJul 17, 23:30 UTC1h 5m
2026-07-17 UAL337 DEN → MFR Jul 17, 17:55 UTCJul 17, 20:04 UTC2h 10m
2026-07-17 UAL2052 - Jul 17, 11:55 UTCJul 17, 15:35 UTC3h 40m
2026-07-17 UAL2254 - Jul 17, 00:30 UTCJul 17, 03:45 UTC3h 15m
2026-07-16 UAL1263 - Jul 16, 20:39 UTCJul 16, 22:59 UTC2h 20m
2026-07-16 UAL2661 - Jul 16, 18:05 UTCJul 16, 19:05 UTC1h 0m
2026-07-16 UAL1348 AUS → SFO Jul 16, 10:35 UTCJul 16, 13:38 UTC3h 3m
2026-07-16 UAL1348 AUS → SFO Jul 16, 10:29 UTCJul 16, 13:40 UTC3h 10m
2026-07-16 UAL2126 SFO → AUS Jul 16, 02:45 UTCJul 16, 05:50 UTC3h 5m
2026-07-15 UAL1948 - Jul 15, 19:55 UTCJul 16, 01:05 UTC5h 10m
2026-07-15 UAL1052 IAD → CUN Jul 15, 15:30 UTCJul 15, 18:20 UTC2h 50m
2026-07-15 UAL1052 EWR → IAD Jul 15, 12:55 UTCJul 15, 14:15 UTC1h 20m
2026-07-14 UAL1053 CUN → EWR Jul 14, 21:10 UTCJul 15, 00:45 UTC3h 34m

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 N37537 page for operator, model, and routing details .

Mode-S A4493F frequently asked

What is Mode-S code A4493F?
A4493F is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N37537.
Where is Mode-S A4493F registered?
Mode-S code A4493F 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 A4493F 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 A4493F, octal 51044477, decimal 10,766,655.
What flights does A4493F operate?
Mode-S A4493F has broadcast 20 distinct callsigns, including UAL308, UAL1058, UAL337, UAL2182, UAL1754.