Apparatus

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sensors Mode-S transponder

A51F4A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N429YX · EMBRAER ERJ-170-200 (long wing) · operated by REPUBLIC AIRWAYS INC

Hex
A51F4A
Octal
51217512
Decimal
10,821,450
Country
US
Tail
N429YX
Type
E75L
No current signal · last broadcast Jul 26, 22:00 UTC
Flights observed
726
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:00 UTC

Last known position

Most recent position reported by Mode-S A51F4A.

Country allocation

The ICAO 24-bit address A51F4A 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
RPA4360 - 11 2026-07-01
RPA4508 - 9 2026-07-17
RPA4628 - 8 2026-07-13
RPA4396 Republic Airlines 8 2026-05-09
RPA4754 Republic Airlines 7 2026-07-21
RPA4630 Republic Airlines 7 2026-07-26
RPA4524 Republic Airlines 7 2026-07-17
RPA4418 Republic Airlines 7 2026-07-26
RPA4412 Republic Airlines 7 2026-07-19
RPA4394 Republic Airlines 7 2026-07-24
RPA4367 Republic Airlines 7 2026-07-23
RPA4795 - 6 2026-07-12
RPA4756 Republic Airlines 6 2026-05-17
RPA4749 - 6 2026-07-12
RPA4676 - 6 2026-06-23
RPA4533 Republic Airlines 6 2026-05-24
RPA4490 Republic Airlines 6 2026-05-15
RPA4456 - 6 2026-07-14
RPA4343 - 6 2026-07-16
RPA4790 - 5 2026-07-05

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA4630 DCA → LGA Jul 26, 20:35 UTCJul 26, 22:00 UTC1h 25m
2026-07-26 RPA4418 AVL → LGA Jul 26, 17:45 UTCJul 26, 19:15 UTC1h 30m
2026-07-26 RPA4418 AVL → LGA Jul 26, 17:42 UTCJul 26, 19:15 UTC1h 33m
2026-07-26 RPA4418 AVL → LGA Jul 26, 14:50 UTCJul 26, 16:25 UTC1h 35m
2026-07-25 RPA4397 PWM → DCA Jul 25, 19:00 UTCJul 25, 21:35 UTC2h 35m
2026-07-25 RPA4397 PWM → DCA Jul 25, 18:59 UTCJul 25, 21:24 UTC2h 25m
2026-07-25 RPA4397 PWM → DCA Jul 25, 15:10 UTCJul 25, 17:50 UTC2h 40m
2026-07-25 RPA4784 CVG → LGA Jul 25, 12:05 UTCJul 25, 13:40 UTC1h 35m
2026-07-24 RPA4779 LGA → MEM Jul 24, 22:25 UTCJul 25, 00:20 UTC1h 55m
2026-07-24 RPA4779 LGA → MEM Jul 24, 22:24 UTCJul 25, 00:19 UTC1h 55m
2026-07-24 RPA4394 DCA → PHL Jul 24, 19:55 UTCJul 24, 21:15 UTC1h 20m
2026-07-24 RPA4394 DCA → PHL Jul 24, 19:54 UTCJul 24, 21:10 UTC1h 16m
2026-07-24 RPA4394 DCA → PHL Jul 24, 17:35 UTCJul 24, 18:50 UTC1h 15m
2026-07-24 RPA4379 ORD → ALB Jul 24, 15:15 UTCJul 24, 16:05 UTC50m
2026-07-24 RPA4379 ORD → ALB Jul 24, 13:30 UTCJul 24, 14:20 UTC50m
2026-07-24 RPA4751 JFK → DCA Jul 24, 10:25 UTCJul 24, 11:50 UTC1h 25m
2026-07-24 RPA4787 DCA → ACK Jul 24, 01:15 UTCJul 24, 02:50 UTC1h 35m
2026-07-23 RPA4685 LGA → CHO Jul 23, 23:25 UTCJul 24, 00:15 UTC50m
2026-07-23 RPA4685 LGA → CHO Jul 23, 20:00 UTCJul 23, 20:55 UTC55m
2026-07-23 RPA4367 DCA → PVD Jul 23, 17:45 UTCJul 23, 18:35 UTC50m
2026-07-23 RPA4367 DCA → PVD Jul 23, 17:41 UTCJul 23, 18:30 UTC49m
2026-07-23 RPA4367 DCA → PVD Jul 23, 14:55 UTCJul 23, 15:25 UTC30m
2026-07-23 RPA4542 YYZ → LGA Jul 23, 11:35 UTCJul 23, 12:45 UTC1h 10m
2026-07-23 RPA4369 PHL → BGR Jul 23, 02:20 UTCJul 23, 03:25 UTC1h 5m
2026-07-22 RPA4481 JFK → RDU Jul 22, 22:35 UTCJul 23, 00:30 UTC1h 55m
2026-07-22 RPA4481 JFK → RDU Jul 22, 22:33 UTCJul 23, 00:29 UTC1h 56m
2026-07-22 RPA4489 AGS → LGA Jul 22, 20:20 UTCJul 22, 21:40 UTC1h 20m
2026-07-22 RPA4658 JFK → RDU Jul 22, 18:10 UTCJul 22, 19:25 UTC1h 15m
2026-07-22 RPA4712 ILM → LGA Jul 22, 14:00 UTCJul 22, 15:55 UTC1h 55m
2026-07-22 RPA4358 PHL → SDF Jul 22, 11:20 UTCJul 22, 12:50 UTC1h 30m
2026-07-22 RPA4358 PHL → SDF Jul 22, 11:18 UTCJul 22, 12:30 UTC1h 12m
2026-07-21 RPA4754 MIA → BUF Jul 21, 17:15 UTCJul 21, 18:15 UTC1h 0m
2026-07-21 RPA4754 MIA → BUF Jul 21, 17:10 UTCJul 21, 18:13 UTC1h 3m
2026-07-21 RPA4754 MIA → BUF Jul 21, 15:05 UTCJul 21, 16:00 UTC55m
2026-07-21 RPA4339 ORD → DCA Jul 21, 11:15 UTCJul 21, 12:55 UTC1h 40m
2026-07-21 RPA4339 ORD → DCA Jul 21, 11:14 UTCJul 21, 12:53 UTC1h 39m
2026-07-20 RPA4668 - Jul 20, 23:40 UTCJul 21, 00:50 UTC1h 10m
2026-07-20 RPA4668 - Jul 20, 21:40 UTCJul 20, 22:25 UTC45m
2026-07-20 RPA4748 DCA → ACK Jul 20, 17:45 UTCJul 20, 20:05 UTC2h 20m
2026-07-20 RPA4748 DCA → ACK Jul 20, 14:20 UTCJul 20, 16:10 UTC1h 50m
2026-07-20 RPA4444 - Jul 20, 11:30 UTCJul 20, 12:40 UTC1h 10m
2026-07-19 RPA4425 - Jul 19, 21:55 UTCJul 19, 22:30 UTC35m
2026-07-19 RPA4425 ORD → MSP Jul 19, 21:50 UTCJul 19, 22:47 UTC57m
2026-07-19 RPA4412 PHL → DTW Jul 19, 19:10 UTCJul 19, 20:10 UTC1h 0m
2026-07-19 RPA4412 PHL → DTW Jul 19, 19:10 UTCJul 19, 20:09 UTC59m
2026-07-19 RPA4609 - Jul 19, 16:55 UTCJul 19, 18:20 UTC1h 25m
2026-07-18 RPA4476 - Jul 18, 14:05 UTCJul 18, 15:20 UTC1h 15m
2026-07-18 RPA4387 LGA → CLE Jul 18, 11:50 UTCJul 18, 13:00 UTC1h 10m
2026-07-18 RPA4387 LGA → CLE Jul 18, 11:48 UTCJul 18, 12:59 UTC1h 11m
2026-07-18 RPA4660 ADW → LGA Jul 18, 03:50 UTCJul 18, 04:30 UTC40m

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 N429YX page for operator, model, and routing details .

Mode-S A51F4A frequently asked

What is Mode-S code A51F4A?
A51F4A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N429YX.
Where is Mode-S A51F4A registered?
Mode-S code A51F4A 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 A51F4A broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:00 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A51F4A, octal 51217512, decimal 10,821,450.
What flights does A51F4A operate?
Mode-S A51F4A has broadcast 20 distinct callsigns, including RPA4360, RPA4508, RPA4628, RPA4396, RPA4754.