Apparatus

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sensors Mode-S transponder

A4FDDB

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N420YX · EMBRAER ERJ-170-200 (long wing) · operated by REPUBLIC AIRWAYS INC

Hex
A4FDDB
Octal
51176733
Decimal
10,812,891
Country
US
Tail
N420YX
Type
E75L
No current signal · last broadcast Jul 26, 22:45 UTC
Flights observed
713
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:45 UTC

Last known position

Most recent position reported by Mode-S A4FDDB.

Country allocation

The ICAO 24-bit address A4FDDB 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
RPA4481 - 10 2026-06-19
RPA4397 - 9 2026-07-18
RPA4590 - 8 2026-07-03
RPA4524 Republic Airlines 8 2026-07-26
RPA4518 - 8 2026-07-04
RPA4739 - 7 2026-07-05
RPA4573 - 7 2026-07-16
RPA4418 Republic Airlines 7 2026-06-15
RPA4389 - 7 2026-07-11
RPA4359 Republic Airlines 7 2026-05-19
RPA4806 - 6 2026-07-17
RPA4754 - 6 2026-06-29
RPA4664 Republic Airlines 6 2026-07-23
RPA4647 Republic Airlines 6 2026-07-22
RPA4643 - 6 2026-07-08
RPA4639 - 6 2026-06-19
RPA4596 Republic Airlines 6 2026-06-02
RPA4569 - 6 2026-06-19
RPA4494 Republic Airlines 6 2026-05-07
RPA4360 Republic Airlines 6 2026-07-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA4524 MSP → LGA Jul 26, 21:55 UTCJul 26, 22:45 UTC50m
2026-07-26 RPA4524 MSP → LGA Jul 26, 17:50 UTCJul 26, 20:20 UTC2h 30m
2026-07-26 RPA4373 DCA → DSM Jul 26, 16:00 UTCJul 26, 16:45 UTC45m
2026-07-26 RPA4373 DCA → DSM Jul 26, 13:20 UTCJul 26, 13:55 UTC35m
2026-07-25 RPA4423 LGA → ILM Jul 25, 21:35 UTCJul 25, 23:00 UTC1h 25m
2026-07-25 RPA4423 LGA → ILM Jul 25, 21:32 UTCJul 25, 22:59 UTC1h 27m
2026-07-25 RPA4423 LGA → ILM Jul 25, 17:55 UTCJul 25, 19:30 UTC1h 35m
2026-07-25 RPA4373 DCA → DSM Jul 25, 15:10 UTCJul 25, 15:55 UTC45m
2026-07-25 RPA4788 LGA → OMA Jul 25, 12:05 UTCJul 25, 13:00 UTC55m
2026-07-25 RPA4788 LGA → OMA Jul 25, 12:01 UTCJul 25, 12:59 UTC58m
2026-07-24 RPA4521 LGA → IND Jul 24, 23:40 UTCJul 25, 00:35 UTC55m
2026-07-24 RPA4655 PIT → LGA Jul 24, 21:25 UTCJul 24, 22:20 UTC55m
2026-07-24 RPA4734 MEM → BOS Jul 24, 19:35 UTCJul 24, 20:40 UTC1h 5m
2026-07-24 RPA4734 MEM → BOS Jul 24, 19:33 UTCJul 24, 20:35 UTC1h 2m
2026-07-24 RPA4350 BOS → CMH Jul 24, 16:35 UTCJul 24, 18:20 UTC1h 45m
2026-07-24 RPA4360 BTV → DCA Jul 24, 12:50 UTCJul 24, 14:20 UTC1h 30m
2026-07-24 RPA4529 BDL → ORD Jul 24, 10:30 UTCJul 24, 11:15 UTC45m
2026-07-24 RPA4529 BDL → ORD Jul 24, 10:26 UTCJul 24, 11:08 UTC42m
2026-07-24 RPA4763 MIA → ALB Jul 24, 01:00 UTCJul 24, 01:35 UTC35m
2026-07-23 RPA4495 PHL → DCA Jul 23, 22:15 UTCJul 23, 23:40 UTC1h 25m
2026-07-23 RPA4495 PHL → DCA Jul 23, 22:12 UTCJul 23, 23:39 UTC1h 27m
2026-07-23 RPA4710 PHL → DCA Jul 23, 19:10 UTCJul 23, 21:20 UTC2h 10m
2026-07-23 RPA4366 DCA → MEM Jul 23, 17:10 UTCJul 23, 18:00 UTC50m
2026-07-23 RPA4716 IND → BOS Jul 23, 13:45 UTCJul 23, 15:30 UTC1h 45m
2026-07-23 RPA4664 JFK → RDU Jul 23, 10:45 UTCJul 23, 12:15 UTC1h 30m
2026-07-23 RPA4664 JFK → RDU Jul 23, 10:44 UTCJul 23, 12:10 UTC1h 26m
2026-07-22 RPA4459 CVG → JFK Jul 22, 23:40 UTCJul 23, 01:15 UTC1h 35m
2026-07-22 RPA4647 RDU → LGA Jul 22, 21:10 UTCJul 22, 22:15 UTC1h 5m
2026-07-22 RPA4647 RDU → LGA Jul 22, 21:08 UTCJul 22, 22:23 UTC1h 15m
2026-07-22 RPA4665 JFK → RDU Jul 22, 17:05 UTCJul 22, 19:15 UTC2h 10m
2026-07-22 RPA4665 JFK → RDU Jul 22, 14:15 UTCJul 22, 15:45 UTC1h 30m
2026-07-22 RPA4622 JFK → BOS Jul 22, 11:10 UTCJul 22, 12:15 UTC1h 5m
2026-07-22 RPA4603 ORD → SDF Jul 22, 01:10 UTCJul 22, 01:55 UTC45m
2026-07-22 RPA4603 ORD → SDF Jul 22, 01:08 UTCJul 22, 01:53 UTC45m
2026-07-21 RPA4759 ORD → TVC Jul 21, 20:25 UTCJul 21, 22:25 UTC2h 0m
2026-07-21 RPA4759 ORD → TVC Jul 21, 17:40 UTCJul 21, 19:00 UTC1h 20m
2026-07-21 RPA4443 ORD → PVD Jul 21, 15:45 UTCJul 21, 16:30 UTC45m
2026-07-21 RPA4435 BOS → IND Jul 21, 12:10 UTCJul 21, 14:50 UTC2h 40m
2026-07-21 RPA4634 BOS → TVC Jul 21, 02:05 UTCJul 21, 02:50 UTC45m
2026-07-20 RPA4390 BOS → JFK Jul 20, 23:15 UTCJul 21, 00:10 UTC54m
2026-07-20 RPA4368 - Jul 20, 18:55 UTCJul 20, 20:45 UTC1h 50m
2026-07-20 RPA4368 IND → BOS Jul 20, 18:51 UTCJul 20, 20:44 UTC1h 53m
2026-07-20 RPA4385 ORD → CHS Jul 20, 16:05 UTCJul 20, 17:35 UTC1h 30m
2026-07-20 RPA4385 ORD → CHS Jul 20, 16:04 UTCJul 20, 17:36 UTC1h 32m
2026-07-20 RPA4808 JFK → RDU Jul 20, 13:15 UTCJul 20, 14:40 UTC1h 25m
2026-07-20 RPA4398 LGA → CMH Jul 20, 10:50 UTCJul 20, 12:00 UTC1h 10m
2026-07-20 RPA4398 LGA → CMH Jul 20, 10:48 UTCJul 20, 11:58 UTC1h 10m
2026-07-19 RPA4470 LGA → ATL Jul 19, 22:20 UTCJul 20, 00:45 UTC2h 25m
2026-07-19 RPA4470 LGA → ATL Jul 19, 22:20 UTCJul 20, 01:20 UTC3h 0m
2026-07-19 RPA4470 LGA → ATL Jul 19, 18:20 UTCJul 19, 21:25 UTC3h 5m

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 N420YX page for operator, model, and routing details .

Mode-S A4FDDB frequently asked

What is Mode-S code A4FDDB?
A4FDDB is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N420YX.
Where is Mode-S A4FDDB registered?
Mode-S code A4FDDB 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 A4FDDB broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A4FDDB, octal 51176733, decimal 10,812,891.
What flights does A4FDDB operate?
Mode-S A4FDDB has broadcast 20 distinct callsigns, including RPA4481, RPA4397, RPA4590, RPA4524, RPA4518.