Apparatus

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sensors Mode-S transponder

A53F5B

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N437YX · EMBRAER ERJ-170-200 (long wing) · operated by REPUBLIC AIRWAYS INC

Hex
A53F5B
Octal
51237533
Decimal
10,829,659
Country
US
Tail
N437YX
Type
E75L
No current signal · last broadcast Jul 21, 02:05 UTC
Flights observed
702
Distinct callsigns
20
Country
US
Last broadcast
Jul 21, 02:05 UTC

Last known position

Most recent position reported by Mode-S A53F5B.

Country allocation

The ICAO 24-bit address A53F5B 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
RPA4700 - 10 2026-07-06
RPA4375 - 10 2026-06-30
RPA4759 - 9 2026-07-12
RPA4738 - 9 2026-07-09
RPA4729 - 7 2026-07-14
RPA4555 - 7 2026-07-15
RPA4428 Republic Airlines 7 2026-06-06
RPA4393 - 7 2026-06-22
RPA4343 Republic Airlines 7 2026-06-09
RPA4809 - 6 2026-07-15
RPA4760 Republic Airlines 6 2026-07-20
RPA4757 Republic Airlines 6 2026-05-07
RPA4756 Republic Airlines 6 2026-06-16
RPA4728 Republic Airlines 6 2026-06-08
RPA4647 - 6 2026-07-11
RPA4637 Republic Airlines 6 2026-07-19
RPA4400 Republic Airlines 6 2026-06-18
RPA4399 - 6 2026-07-08
RPA4373 Republic Airlines 6 2026-05-02
RPA4360 Republic Airlines 6 2026-06-10

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-21 RPA4392 DCA → LGA Jul 21, 00:15 UTCJul 21, 02:05 UTC1h 50m
2026-07-20 RPA4632 LGA → ORD Jul 20, 22:05 UTCJul 20, 22:45 UTC40m
2026-07-20 RPA4632 LGA → ORD Jul 20, 22:04 UTCJul 20, 22:49 UTC45m
2026-07-20 RPA4760 JFK → CLE Jul 20, 19:10 UTCJul 20, 20:50 UTC1h 40m
2026-07-20 RPA4760 JFK → CLE Jul 20, 19:07 UTCJul 20, 20:50 UTC1h 43m
2026-07-20 RPA4760 JFK → CLE Jul 20, 16:20 UTCJul 20, 18:10 UTC1h 50m
2026-07-20 RPA4691 JFK → RIC Jul 20, 14:00 UTCJul 20, 15:15 UTC1h 15m
2026-07-20 RPA4352 SDF → DCA Jul 20, 11:55 UTCJul 20, 12:45 UTC50m
2026-07-20 RPA4352 SDF → DCA Jul 20, 11:50 UTCJul 20, 13:01 UTC1h 11m
2026-07-19 RPA4637 DCA → BDL Jul 19, 23:20 UTCJul 20, 00:30 UTC1h 10m
2026-07-19 RPA4637 DCA → BDL Jul 19, 23:00 UTCJul 19, 23:15 UTC15m
2026-07-19 RPA4637 DCA → BDL Jul 19, 22:40 UTCJul 19, 22:50 UTC10m
2026-07-19 RPA4545 - Jul 19, 20:20 UTCJul 19, 21:15 UTC55m
2026-07-19 RPA4545 - Jul 19, 17:50 UTCJul 19, 18:40 UTC50m
2026-07-19 RPA4602 CLE → JFK Jul 19, 15:20 UTCJul 19, 16:25 UTC1h 5m
2026-07-19 RPA4602 CLE → JFK Jul 19, 15:18 UTCJul 19, 16:22 UTC1h 4m
2026-07-19 RPA4649 DCA → MVY Jul 19, 13:15 UTCJul 19, 14:10 UTC55m
2026-07-19 RPA4649 DCA → MVY Jul 19, 13:11 UTCJul 19, 14:09 UTC58m
2026-07-19 RPA4786 CHA → DCA Jul 19, 10:05 UTCJul 19, 11:00 UTC55m
2026-07-19 RPA4662 BOS → ROC Jul 19, 01:05 UTCJul 19, 02:15 UTC1h 10m
2026-07-18 RPA4507 BOS → CVG Jul 18, 22:15 UTCJul 19, 00:10 UTC1h 55m
2026-07-18 RPA4507 BOS → CVG Jul 18, 22:12 UTCJul 19, 00:09 UTC1h 57m
2026-07-18 RPA4507 BOS → CVG Jul 18, 18:30 UTCJul 18, 20:35 UTC2h 5m
2026-07-18 RPA4367 DCA → PVD Jul 18, 17:00 UTCJul 18, 17:35 UTC35m
2026-07-18 RPA4411 BNA → LGA Jul 18, 11:45 UTCJul 18, 13:50 UTC2h 5m
2026-07-18 RPA4392 DCA → LGA Jul 18, 00:19 UTCJul 18, 02:09 UTC1h 50m
2026-07-18 RPA4392 DCA → LGA Jul 18, 00:16 UTCJul 18, 02:04 UTC1h 48m
2026-07-17 RPA4632 - Jul 17, 22:40 UTCJul 17, 23:25 UTC45m
2026-07-17 RPA4632 BOS → BOS Jul 17, 22:05 UTCJul 17, 22:15 UTC10m
2026-07-17 RPA4760 - Jul 17, 19:05 UTCJul 17, 20:50 UTC1h 45m
2026-07-17 RPA4760 CVG → BOS Jul 17, 19:04 UTCJul 17, 20:47 UTC1h 43m
2026-07-17 RPA4760 BOS → CVG Jul 17, 16:04 UTCJul 17, 17:50 UTC1h 45m
2026-07-17 RPA4691 - Jul 17, 13:55 UTCJul 17, 14:44 UTC50m
2026-07-17 RPA4691 DCA → BOS Jul 17, 13:53 UTCJul 17, 14:55 UTC1h 2m
2026-07-17 RPA4505 - Jul 17, 12:10 UTCJul 17, 12:30 UTC20m
2026-07-17 RPA4505 - Jul 17, 11:10 UTCJul 17, 12:04 UTC55m
2026-07-17 RPA4505 BOS → DCA Jul 17, 11:09 UTCJul 17, 12:26 UTC1h 17m
2026-07-17 RPA4768 LGA → BOS Jul 17, 01:25 UTCJul 17, 02:10 UTC45m
2026-07-16 RPA4461 - Jul 16, 22:45 UTCJul 16, 23:59 UTC1h 15m
2026-07-16 RPA4461 - Jul 16, 21:40 UTCJul 16, 22:40 UTC1h 0m
2026-07-16 RPA4461 - Jul 16, 18:00 UTCJul 16, 20:09 UTC2h 10m
2026-07-16 RPA4645 DCA → LGA Jul 16, 16:15 UTCJul 16, 17:00 UTC45m
2026-07-16 RPA4766 - Jul 16, 12:00 UTCJul 16, 14:10 UTC2h 10m
2026-07-16 RPA4694 - Jul 16, 01:10 UTCJul 16, 03:15 UTC2h 5m
2026-07-15 RPA4555 - Jul 15, 22:35 UTCJul 15, 23:50 UTC1h 15m
2026-07-15 RPA4555 - Jul 15, 20:45 UTCJul 15, 21:50 UTC1h 5m
2026-07-15 RPA4809 - Jul 15, 18:25 UTCJul 15, 19:45 UTC1h 20m
2026-07-15 RPA4809 ORD → DCA Jul 15, 18:22 UTCJul 15, 19:51 UTC1h 29m
2026-07-15 RPA4478 - Jul 15, 15:50 UTCJul 15, 16:55 UTC1h 5m
2026-07-15 RPA4478 PIT → ORD Jul 15, 15:49 UTCJul 15, 16:51 UTC1h 2m

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 N437YX page for operator, model, and routing details .

Mode-S A53F5B frequently asked

What is Mode-S code A53F5B?
A53F5B is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N437YX.
Where is Mode-S A53F5B registered?
Mode-S code A53F5B 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 A53F5B broadcasting right now?
No active broadcast right now. Last signal was Jul 21, 02:05 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A53F5B, octal 51237533, decimal 10,829,659.
What flights does A53F5B operate?
Mode-S A53F5B has broadcast 20 distinct callsigns, including RPA4700, RPA4375, RPA4759, RPA4738, RPA4729.