Apparatus

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sensors Mode-S transponder

A57F04

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N453UA · AIRBUS A-320 · operated by UNITED AIRLINES INC

Hex
A57F04
Octal
51277404
Decimal
10,845,956
Country
US
Tail
N453UA
Type
A320
No current signal · last broadcast Jul 26, 23:00 UTC
Flights observed
442
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Last known position

Most recent position reported by Mode-S A57F04.

Country allocation

The ICAO 24-bit address A57F04 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
UAL1766 - 6 2026-07-21
UAL303 - 5 2026-07-11
UAL1857 - 5 2026-07-10
UAL1306 - 5 2026-07-13
UAL1285 - 5 2026-07-11
UAL817 - 4 2026-06-25
UAL739 United Airlines 4 2026-05-27
UAL704 - 4 2026-07-12
UAL654 United Airlines 4 2026-05-16
UAL562 United Airlines 4 2026-07-03
UAL561 - 4 2026-07-11
UAL485 United Airlines 4 2026-04-19
UAL421 United Airlines 4 2026-05-19
UAL2334 - 4 2026-07-07
UAL2196 - 4 2026-06-29
UAL1842 - 4 2026-07-10
UAL1610 - 4 2026-07-17
UAL1337 - 4 2026-07-06
UAL1269 - 4 2026-07-12
UAL1048 - 4 2026-07-21

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1094 DEN → YYZ Jul 26, 22:35 UTCJul 26, 23:00 UTC25m
2026-07-26 UAL2793 IAD → EWR Jul 26, 18:20 UTCJul 26, 20:50 UTC2h 30m
2026-07-26 UAL1247 EWR → FLL Jul 26, 14:20 UTCJul 26, 16:35 UTC2h 15m
2026-07-25 UAL498 PDX → EWR Jul 25, 21:05 UTCJul 25, 22:55 UTC1h 50m
2026-07-25 UAL1112 BOS → DEN Jul 25, 17:25 UTCJul 25, 19:15 UTC1h 50m
2026-07-25 UAL1112 BOS → DEN Jul 25, 17:27 UTCJul 25, 19:16 UTC1h 49m
2026-07-25 UAL1846 ORD → CMH Jul 25, 13:15 UTCJul 25, 15:50 UTC2h 35m
2026-07-25 UAL1220 DEN → DTW Jul 25, 00:20 UTCJul 25, 02:40 UTC2h 20m
2026-07-24 UAL2110 SAN → SFO Jul 24, 17:55 UTCJul 24, 22:25 UTC4h 30m
2026-07-24 UAL2811 CLE → SFO Jul 24, 02:50 UTCJul 24, 16:10 UTC13h 20m
2026-07-23 UAL1866 FLL → EWR Jul 23, 20:55 UTCJul 24, 00:30 UTC3h 35m
2026-07-23 UAL1866 FLL → EWR Jul 23, 20:52 UTCJul 24, 00:28 UTC3h 36m
2026-07-23 UAL1786 LAX → CLE Jul 23, 16:50 UTCJul 23, 19:40 UTC2h 50m
2026-07-23 UAL1841 SFO → IAH Jul 23, 03:15 UTCJul 23, 05:20 UTC2h 5m
2026-07-22 UAL1208 IAH → EWR Jul 22, 23:55 UTCJul 23, 01:55 UTC2h 0m
2026-07-22 UAL1195 DTW → ORD Jul 22, 19:00 UTCJul 22, 20:15 UTC1h 15m
2026-07-22 UAL361 DEN → OMA Jul 22, 16:35 UTCJul 22, 17:50 UTC1h 15m
2026-07-22 UAL1256 RDU → DEN Jul 22, 12:55 UTCJul 22, 15:30 UTC2h 35m
2026-07-22 UAL1256 RDU → DEN Jul 22, 13:01 UTCJul 22, 15:24 UTC2h 23m
2026-07-22 UAL2473 LAX → EWR Jul 22, 01:10 UTCJul 22, 03:35 UTC2h 25m
2026-07-21 UAL1766 - Jul 21, 20:15 UTCJul 21, 22:35 UTC2h 20m
2026-07-21 UAL1048 DEN → BNA Jul 21, 16:10 UTCJul 21, 18:15 UTC2h 5m
2026-07-21 UAL1049 CUN → EWR Jul 21, 12:30 UTCJul 21, 14:25 UTC1h 55m
2026-07-21 UAL1913 IAH → LAS Jul 21, 05:05 UTCJul 21, 06:50 UTC1h 45m
2026-07-21 UAL1035 SJC → DEN Jul 21, 01:45 UTCJul 21, 04:00 UTC2h 15m
2026-07-20 UAL1883 SFO → SJD Jul 20, 22:20 UTCJul 21, 00:30 UTC2h 9m
2026-07-20 UAL502 IAH → DCA Jul 20, 18:35 UTCJul 20, 20:55 UTC2h 20m
2026-07-20 UAL1366 IAD → DEN Jul 20, 15:50 UTCJul 20, 17:10 UTC1h 20m
2026-07-20 UAL1460 SFO → DEN Jul 20, 01:05 UTCJul 20, 02:20 UTC1h 15m
2026-07-19 UAL1109 DEN → BNA Jul 19, 20:30 UTCJul 19, 22:45 UTC2h 15m
2026-07-19 UAL1109 DEN → BNA Jul 19, 20:14 UTCJul 19, 22:41 UTC2h 27m
2026-07-19 UAL1944 YYZ → DEN Jul 19, 15:02 UTCJul 19, 17:50 UTC2h 48m
2026-07-19 UAL1944 YYZ → DEN Jul 19, 15:00 UTCJul 19, 17:55 UTC2h 55m
2026-07-18 UAL1094 DEN → YYZ Jul 18, 22:40 UTCJul 19, 01:25 UTC2h 45m
2026-07-18 UAL1741 MSY → EWR Jul 18, 20:05 UTCJul 18, 21:05 UTC1h 0m
2026-07-18 UAL1402 DEN → ABQ Jul 18, 17:45 UTCJul 18, 18:30 UTC45m
2026-07-18 UAL2383 PHL → DEN Jul 18, 13:15 UTCJul 18, 16:10 UTC2h 55m
2026-07-18 UAL2671 DEN → RDU Jul 18, 00:12 UTCJul 18, 03:11 UTC2h 59m
2026-07-18 UAL2671 DEN → RDU Jul 18, 00:19 UTCJul 18, 03:20 UTC3h 1m
2026-07-17 UAL514 AUS → EWR Jul 17, 20:25 UTCJul 17, 21:55 UTC1h 30m
2026-07-17 UAL476 DEN → CID Jul 17, 17:42 UTCJul 17, 18:54 UTC1h 12m
2026-07-17 UAL476 DEN → CID Jul 17, 17:30 UTCJul 17, 19:00 UTC1h 30m
2026-07-17 UAL1610 - Jul 17, 14:30 UTCJul 17, 16:00 UTC1h 30m
2026-07-17 UAL1126 DEN → FAR Jul 17, 00:40 UTCJul 17, 02:05 UTC1h 25m
2026-07-16 UAL498 - Jul 16, 20:55 UTCJul 16, 22:55 UTC2h 0m
2026-07-16 UAL1112 - Jul 16, 17:20 UTCJul 16, 19:10 UTC1h 50m
2026-07-16 UAL1610 - Jul 16, 14:25 UTCJul 16, 15:49 UTC1h 25m
2026-07-16 UAL1126 DEN → FAR Jul 16, 00:40 UTCJul 16, 02:05 UTC1h 25m
2026-07-15 UAL1766 - Jul 15, 20:20 UTCJul 15, 22:30 UTC2h 10m
2026-07-15 UAL1048 DEN → BNA Jul 15, 16:15 UTCJul 15, 18:30 UTC2h 15m

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 N453UA page for operator, model, and routing details .

Mode-S A57F04 frequently asked

What is Mode-S code A57F04?
A57F04 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N453UA.
Where is Mode-S A57F04 registered?
Mode-S code A57F04 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 A57F04 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 A57F04, octal 51277404, decimal 10,845,956.
What flights does A57F04 operate?
Mode-S A57F04 has broadcast 20 distinct callsigns, including UAL1766, UAL303, UAL1857, UAL1306, UAL1285.