Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A1F557

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N225UA · BOEING 777-200 · operated by UNITED AIRLINES INC

Hex
A1F557
Octal
50372527
Decimal
10,614,103
Country
US
Tail
N225UA
Type
B772
No current signal · last broadcast Jul 26, 17:45 UTC
Flights observed
269
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 17:45 UTC

Last known position

Most recent position reported by Mode-S A1F557.

Country allocation

The ICAO 24-bit address A1F557 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
UAL56 United Airlines 13 2026-07-26
UAL943 United Airlines 12 2026-07-25
UAL915 United Airlines 12 2026-07-25
UAL70 United Airlines 12 2026-05-25
UAL18 United Airlines 10 2026-05-25
UAL942 United Airlines 9 2026-07-25
UAL879 - 9 2026-07-02
UAL933 - 8 2026-07-16
UAL905 United Airlines 8 2026-05-22
UAL19 United Airlines 8 2026-05-24
UAL14 United Airlines 8 2026-05-22
UAL71 United Airlines 7 2026-05-26
UAL925 - 6 2026-07-03
UAL5 - 6 2026-07-03
UAL47 United Airlines 6 2026-06-13
UAL932 - 5 2026-07-09
UAL885 - 5 2026-07-07
UAL880 United Airlines 5 2026-06-04
UAL46 United Airlines 5 2026-06-13
UAL984 - 4 2026-07-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL56 CDG → EWR Jul 26, 10:15 UTCJul 26, 17:40 UTC7h 25m
2026-07-26 UAL56 CDG → EWR Jul 26, 09:44 UTCJul 26, 17:37 UTC7h 53m
2026-07-25 UAL915 IAD → CDG Jul 25, 22:45 UTCJul 26, 05:35 UTC6h 50m
2026-07-25 UAL943 LIS → IAD Jul 25, 11:46 UTCJul 25, 18:53 UTC7h 7m
2026-07-25 UAL943 LIS → IAD Jul 25, 11:45 UTCJul 25, 18:55 UTC7h 10m
2026-07-25 UAL942 IAD → LIS Jul 25, 02:35 UTCJul 25, 09:10 UTC6h 35m
2026-07-24 UAL914 CDG → IAD Jul 24, 10:40 UTCJul 24, 18:25 UTC7h 45m
2026-07-23 UAL990 SFO → CDG Jul 23, 22:05 UTCJul 24, 07:55 UTC9h 50m
2026-07-23 UAL34 KIX → SFO Jul 23, 08:15 UTCJul 23, 17:47 UTC9h 32m
2026-07-23 UAL34 KIX → SFO Jul 23, 08:05 UTCJul 23, 17:45 UTC9h 40m
2026-07-22 UAL35 SFO → KIX Jul 22, 18:35 UTCJul 22, 19:05 UTC30m
2026-07-22 UAL35 SFO → KIX Jul 22, 18:35 UTCJul 23, 05:08 UTC10h 33m
2026-07-21 UAL59 FRA → SFO Jul 21, 11:20 UTCJul 21, 22:15 UTC10h 55m
2026-07-21 UAL59 FRA → SFO Jul 21, 11:24 UTCJul 21, 22:09 UTC10h 45m
2026-07-20 UAL58 SFO → FRA Jul 20, 21:55 UTCJul 21, 07:50 UTC9h 55m
2026-07-20 UAL984 - Jul 20, 07:50 UTCJul 20, 18:55 UTC11h 5m
2026-07-19 UAL57 EWR → CDG Jul 19, 22:40 UTCJul 20, 05:15 UTC6h 35m
2026-07-18 UAL56 CDG → EWR Jul 18, 08:05 UTCJul 18, 09:40 UTC1h 35m
2026-07-18 UAL56 CDG → EWR Jul 18, 08:14 UTCJul 18, 15:17 UTC7h 3m
2026-07-17 UAL915 IAD → CDG Jul 17, 22:31 UTCJul 18, 05:28 UTC6h 57m
2026-07-17 UAL915 - Jul 17, 22:35 UTCJul 18, 00:29 UTC1h 55m
2026-07-17 UAL943 LIS → IAD Jul 17, 11:55 UTCJul 17, 19:09 UTC7h 15m
2026-07-17 UAL942 IAD → LIS Jul 17, 03:20 UTCJul 17, 09:50 UTC6h 30m
2026-07-16 UAL933 FRA → IAD Jul 16, 15:35 UTCJul 16, 23:25 UTC7h 50m
2026-07-16 UAL926 - Jul 16, 03:20 UTCJul 16, 05:45 UTC2h 25m
2026-07-16 UAL926 SFO → FRA Jul 16, 03:04 UTCJul 16, 13:23 UTC10h 19m
2026-07-15 UAL889 PEK → SFO Jul 15, 09:51 UTCJul 15, 21:17 UTC11h 26m
2026-07-15 UAL889 - Jul 15, 03:25 UTCJul 15, 21:20 UTC17h 55m
2026-07-14 UAL888 - Jul 14, 18:20 UTCJul 15, 12:35 UTC18h 14m
2026-07-13 UAL195 MUC → SFO Jul 13, 10:15 UTCJul 13, 21:45 UTC11h 30m
2026-07-12 UAL102 - Jul 12, 22:25 UTCJul 13, 08:05 UTC9h 40m
2026-07-11 UAL4 - Jul 11, 13:25 UTCJul 11, 22:45 UTC9h 20m
2026-07-11 UAL924 IAD → LHR Jul 11, 04:05 UTCJul 11, 10:45 UTC6h 40m
2026-07-10 UAL943 LIS → IAD Jul 10, 12:10 UTCJul 10, 19:35 UTC7h 25m
2026-07-10 UAL942 IAD → LIS Jul 10, 03:35 UTCJul 10, 09:55 UTC6h 20m
2026-07-10 UAL942 IAD → LIS Jul 10, 03:18 UTCJul 10, 09:44 UTC6h 26m
2026-07-09 UAL933 FRA → IAD Jul 9, 15:30 UTCJul 10, 00:05 UTC8h 35m
2026-07-09 UAL933 FRA → IAD Jul 9, 15:31 UTCJul 10, 00:00 UTC8h 29m
2026-07-09 UAL932 IAD → FRA Jul 9, 03:05 UTCJul 9, 10:20 UTC7h 15m
2026-07-08 UAL933 - Jul 8, 15:55 UTCJul 8, 17:45 UTC1h 50m
2026-07-08 UAL933 FRA → IAD Jul 8, 15:46 UTCJul 9, 00:00 UTC8h 14m
2026-07-08 UAL932 IAD → FRA Jul 8, 03:03 UTCJul 8, 10:17 UTC7h 14m
2026-07-08 UAL932 - Jul 8, 03:05 UTCJul 8, 05:00 UTC1h 55m
2026-07-07 UAL885 - Jul 7, 10:55 UTCJul 7, 19:35 UTC8h 40m
2026-07-07 UAL884 IAD → FCO Jul 7, 00:30 UTCJul 7, 08:30 UTC8h 0m
2026-07-06 UAL884 IAD → FCO Jul 6, 23:18 UTCJul 7, 08:27 UTC9h 9m
2026-07-06 UAL885 - Jul 6, 11:20 UTCJul 6, 20:25 UTC9h 5m
2026-07-06 UAL884 IAD → FCO Jul 6, 01:00 UTCJul 6, 08:40 UTC7h 40m
2026-07-04 UAL943 LIS → IAD Jul 4, 11:30 UTCJul 4, 18:30 UTC7h 0m
2026-07-04 UAL942 IAD → LIS Jul 4, 02:40 UTCJul 4, 09:10 UTC6h 30m

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 N225UA page for operator, model, and routing details .

Mode-S A1F557 frequently asked

What is Mode-S code A1F557?
A1F557 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N225UA.
Where is Mode-S A1F557 registered?
Mode-S code A1F557 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 A1F557 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 17:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1F557, octal 50372527, decimal 10,614,103.
What flights does A1F557 operate?
Mode-S A1F557 has broadcast 20 distinct callsigns, including UAL56, UAL943, UAL915, UAL70, UAL18.