Apparatus

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sensors Mode-S transponder

A4D04C

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N409YX · EMBRAER ERJ-170-200 (long wing) · operated by REPUBLIC AIRWAYS INC

Hex
A4D04C
Octal
51150114
Decimal
10,801,228
Country
US
Tail
N409YX
Type
E75L
No current signal · last broadcast Jul 26, 23:00 UTC
Flights observed
732
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 23:00 UTC

Last known position

Most recent position reported by Mode-S A4D04C.

Country allocation

The ICAO 24-bit address A4D04C 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
RPA4745 - 16 2026-07-19
RPA4738 Republic Airlines 10 2026-07-24
RPA4500 Republic Airlines 9 2026-07-18
RPA4687 - 8 2026-07-11
RPA4560 - 8 2026-07-04
RPA4749 - 7 2026-06-27
RPA4619 - 7 2026-06-30
RPA4403 - 7 2026-06-16
RPA4711 Republic Airlines 6 2026-07-20
RPA4676 - 6 2026-07-15
RPA4553 - 6 2026-07-17
RPA4539 Republic Airlines 6 2026-06-03
RPA4538 - 6 2026-07-16
RPA4532 - 6 2026-07-15
RPA4465 Republic Airlines 6 2026-06-08
RPA4454 - 6 2026-06-23
RPA4432 Republic Airlines 6 2026-06-15
RPA4378 Republic Airlines 6 2026-05-15
RPA4764 Republic Airlines 5 2026-04-27
RPA4756 Republic Airlines 5 2026-06-08

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA4456 JFK → BOS Jul 26, 21:20 UTCJul 26, 23:00 UTC1h 40m
2026-07-26 RPA409 CLE → DCA Jul 26, 18:40 UTCJul 26, 20:00 UTC1h 20m
2026-07-26 RPA4349 JFK → BOS Jul 26, 16:05 UTCJul 26, 17:25 UTC1h 20m
2026-07-26 RPA4716 IND → BOS Jul 26, 13:15 UTCJul 26, 15:10 UTC1h 55m
2026-07-26 RPA4716 IND → BOS Jul 26, 13:12 UTCJul 26, 15:10 UTC1h 58m
2026-07-26 RPA4664 JFK → RDU Jul 26, 10:45 UTCJul 26, 12:05 UTC1h 20m
2026-07-25 RPA4452 PVD → DCA Jul 25, 21:20 UTCJul 25, 22:30 UTC1h 10m
2026-07-25 RPA4452 PVD → DCA Jul 25, 21:18 UTCJul 25, 22:13 UTC55m
2026-07-25 RPA4452 PVD → DCA Jul 25, 18:25 UTCJul 25, 19:40 UTC1h 15m
2026-07-25 RPA4515 IND → LGA Jul 25, 15:20 UTCJul 25, 16:45 UTC1h 25m
2026-07-25 RPA4515 IND → LGA Jul 25, 12:50 UTCJul 25, 14:05 UTC1h 15m
2026-07-25 RPA4433 BOS → JFK Jul 25, 01:45 UTCJul 25, 03:00 UTC1h 15m
2026-07-25 RPA4433 BOS → JFK Jul 25, 01:44 UTCJul 25, 02:56 UTC1h 12m
2026-07-24 RPA4585 BOS → IND Jul 24, 22:55 UTCJul 25, 01:00 UTC2h 5m
2026-07-24 RPA4585 BOS → IND Jul 24, 22:53 UTCJul 25, 01:00 UTC2h 7m
2026-07-24 RPA4738 DCA → MCI Jul 24, 20:35 UTCJul 24, 22:00 UTC1h 25m
2026-07-24 RPA4738 DCA → MCI Jul 24, 16:45 UTCJul 24, 18:15 UTC1h 30m
2026-07-24 RPA4691 JFK → RIC Jul 24, 14:05 UTCJul 24, 15:05 UTC1h 0m
2026-07-24 RPA4505 CVG → BOS Jul 24, 11:10 UTCJul 24, 12:25 UTC1h 15m
2026-07-24 RPA4768 DCA → BDL Jul 24, 01:40 UTCJul 24, 02:20 UTC40m
2026-07-24 RPA4768 DCA → BDL Jul 24, 01:37 UTCJul 24, 02:19 UTC42m
2026-07-23 RPA4461 JFK → ORF Jul 23, 22:00 UTCJul 24, 00:20 UTC2h 20m
2026-07-23 RPA4461 JFK → ORF Jul 23, 18:20 UTCJul 23, 20:25 UTC2h 5m
2026-07-23 RPA4645 PHL → BTV Jul 23, 16:05 UTCJul 23, 16:45 UTC40m
2026-07-23 RPA4645 PHL → BTV Jul 23, 16:01 UTCJul 23, 16:43 UTC42m
2026-07-23 RPA4393 JFK → BOS Jul 23, 13:40 UTCJul 23, 14:25 UTC45m
2026-07-23 RPA4578 ALB → MIA Jul 23, 10:15 UTCJul 23, 11:15 UTC1h 0m
2026-07-23 RPA4578 ALB → MIA Jul 23, 10:09 UTCJul 23, 11:11 UTC1h 2m
2026-07-23 RPA4577 JFK → DCA Jul 23, 01:30 UTCJul 23, 02:50 UTC1h 20m
2026-07-22 RPA4423 LGA → ILM Jul 22, 22:55 UTCJul 23, 00:20 UTC1h 25m
2026-07-22 RPA4423 LGA → ILM Jul 22, 20:10 UTCJul 22, 21:45 UTC1h 35m
2026-07-22 RPA4601 MEM → LGA Jul 22, 16:45 UTCJul 22, 18:15 UTC1h 30m
2026-07-22 RPA4601 MEM → LGA Jul 22, 13:55 UTCJul 22, 15:35 UTC1h 40m
2026-07-22 RPA4595 - Jul 22, 11:10 UTCJul 22, 12:05 UTC55m
2026-07-21 RPA9691 CMH → BHM Jul 21, 21:05 UTCJul 21, 22:40 UTC1h 35m
2026-07-21 RPA4416 JFK → CMH Jul 21, 13:55 UTCJul 21, 16:10 UTC2h 15m
2026-07-21 RPA4549 SDF → DCA Jul 21, 10:15 UTCJul 21, 11:20 UTC1h 5m
2026-07-21 RPA4466 PHL → SDF Jul 21, 01:05 UTCJul 21, 02:30 UTC1h 25m
2026-07-20 RPA4652 ORD → RDU Jul 20, 22:55 UTCJul 21, 00:00 UTC1h 4m
2026-07-20 RPA4652 ORD → RDU Jul 20, 20:15 UTCJul 20, 21:20 UTC1h 5m
2026-07-20 RPA4652 ORD → RDU Jul 20, 19:45 UTCJul 20, 19:50 UTC5m
2026-07-20 RPA4735 PHL → SDF Jul 20, 17:25 UTCJul 20, 18:30 UTC1h 5m
2026-07-20 RPA4735 PHL → SDF Jul 20, 15:10 UTCJul 20, 16:00 UTC50m
2026-07-20 RPA4711 GSO → LGA Jul 20, 12:25 UTCJul 20, 13:35 UTC1h 10m
2026-07-20 RPA4711 GSO → LGA Jul 20, 12:21 UTCJul 20, 13:26 UTC1h 5m
2026-07-20 RPA4445 YYZ → LGA Jul 20, 02:40 UTCJul 20, 03:25 UTC45m
2026-07-19 RPA4745 - Jul 19, 22:35 UTCJul 19, 23:45 UTC1h 10m
2026-07-19 RPA4745 - Jul 19, 20:35 UTCJul 19, 21:40 UTC1h 5m
2026-07-19 RPA4643 ORF → ORD Jul 19, 16:10 UTCJul 19, 18:10 UTC2h 0m
2026-07-19 RPA4643 - Jul 19, 13:25 UTCJul 19, 15:15 UTC1h 50m

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 N409YX page for operator, model, and routing details .

Mode-S A4D04C frequently asked

What is Mode-S code A4D04C?
A4D04C is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N409YX.
Where is Mode-S A4D04C registered?
Mode-S code A4D04C 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 A4D04C 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 A4D04C, octal 51150114, decimal 10,801,228.
What flights does A4D04C operate?
Mode-S A4D04C has broadcast 20 distinct callsigns, including RPA4745, RPA4738, RPA4500, RPA4687, RPA4560.