sensors Mode-S transponder

A245FB

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N24573 · operated by UNITED AIRLINES INC

Hex
A245FB
Octal
50442773
Decimal
10,634,747
Country
US
Tail
N24573
No current signal · last broadcast 7h ago
Flights observed
26
Distinct callsigns
19
Country
US
Last broadcast
7h ago

Last known position

Most recent position reported by Mode-S A245FB.

Country allocation

The ICAO 24-bit address A245FB 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 19 distinct

Callsign Airline Flights Last seen
UAL1998 - 3 2026-07-14
UAL1755 - 3 2026-07-11
UAL4214 - 2 2026-07-01
UAL2430 - 2 2026-07-09
UAL1792 - 2 2026-07-09
UAL800 - 1 2026-07-10
UAL587 - 1 2026-07-13
UAL511 - 1 2026-07-11
UAL3885 - 1 2026-07-03
UAL3876 - 1 2026-07-08
UAL2649 - 1 2026-07-11
UAL2455 - 1 2026-07-08
UAL2329 - 1 2026-07-13
UAL1568 - 1 2026-07-12
UAL1505 - 1 2026-07-08
UAL1421 - 1 2026-07-11
UAL1232 - 1 2026-07-10
UAL1150 - 1 2026-07-09
UAL1107 - 1 2026-07-12

Recent flights last 26

DateFlightRouteTakeoffLandingDuration
2026-07-14 UAL1998 - Jul 14, 01:10 UTCJul 14, 01:25 UTC15m
2026-07-13 UAL1998 EWR → ORD Jul 13, 23:40 UTCJul 14, 00:53 UTC1h 13m
2026-07-13 UAL1998 - Jul 13, 23:35 UTCJul 14, 00:45 UTC1h 10m
2026-07-13 UAL2329 ORD → EWR Jul 13, 20:15 UTCJul 13, 21:55 UTC1h 40m
2026-07-13 UAL587 - Jul 13, 14:15 UTCJul 13, 18:00 UTC3h 45m
2026-07-12 UAL1107 ORD → SNA Jul 12, 21:50 UTCJul 13, 01:20 UTC3h 30m
2026-07-12 UAL1568 SFO → ORD Jul 12, 15:30 UTCJul 12, 19:15 UTC3h 45m
2026-07-11 UAL511 ORD → SFO Jul 11, 22:20 UTCJul 12, 02:10 UTC3h 50m
2026-07-11 UAL1755 - Jul 11, 19:30 UTCJul 11, 19:40 UTC10m
2026-07-11 UAL1755 - Jul 11, 16:45 UTCJul 11, 18:45 UTC2h 0m
2026-07-11 UAL1755 FLL → ORD Jul 11, 16:44 UTCJul 11, 19:15 UTC2h 31m
2026-07-11 UAL1421 - Jul 11, 12:30 UTCJul 11, 15:05 UTC2h 35m
2026-07-11 UAL2649 DEN → ORD Jul 11, 03:30 UTCJul 11, 05:20 UTC1h 50m
2026-07-10 UAL800 BOS → DEN Jul 10, 21:15 UTCJul 11, 01:40 UTC4h 25m
2026-07-10 UAL1232 DEN → BOS Jul 10, 16:00 UTCJul 10, 19:45 UTC3h 45m
2026-07-09 UAL1150 ORD → DEN Jul 9, 18:40 UTCJul 9, 20:45 UTC2h 5m
2026-07-09 UAL2430 DEN → ORD Jul 9, 14:18 UTCJul 9, 16:03 UTC1h 45m
2026-07-09 UAL2430 DEN → ORD Jul 9, 14:15 UTCJul 9, 16:15 UTC2h 0m
2026-07-09 UAL1792 EWR → DEN Jul 9, 01:27 UTCJul 9, 05:00 UTC3h 33m
2026-07-09 UAL1792 EWR → DEN Jul 9, 01:25 UTCJul 9, 05:05 UTC3h 40m
2026-07-08 UAL1505 DEN → EWR Jul 8, 20:00 UTCJul 8, 23:25 UTC3h 25m
2026-07-08 UAL2455 - Jul 8, 14:15 UTCJul 8, 17:40 UTC3h 25m
2026-07-08 UAL3876 MLB → EWR Jul 8, 04:15 UTCJul 8, 06:20 UTC2h 5m
2026-07-03 UAL3885 TPA → MLB Jul 3, 15:40 UTCJul 3, 16:10 UTC30m
2026-07-01 UAL4214 - Jul 1, 18:05 UTCJul 1, 19:10 UTC1h 5m
2026-07-01 UAL4214 BFM → TPA Jul 1, 17:28 UTCJul 1, 19:08 UTC1h 40m

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 N24573 page for operator, model, and routing details .

Mode-S A245FB frequently asked

What is Mode-S code A245FB?
A245FB is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N24573.
Where is Mode-S A245FB registered?
Mode-S code A245FB 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 A245FB broadcasting right now?
No active broadcast right now. Last signal was 7h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A245FB, octal 50442773, decimal 10,634,747.
What flights does A245FB operate?
Mode-S A245FB has broadcast 19 distinct callsigns, including UAL1998, UAL1755, UAL4214, UAL2430, UAL1792.