Apparatus

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sensors Mode-S transponder

AA2B21

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N754YX · operated by REPUBLIC AIRWAYS INC

Hex
AA2B21
Octal
52425441
Decimal
11,152,161
Country
US
Tail
N754YX
Type
E75L
No current signal · last broadcast Jul 26, 22:15 UTC
Flights observed
654
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:15 UTC

Last known position

Most recent position reported by Mode-S AA2B21.

Country allocation

The ICAO 24-bit address AA2B21 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
RPA3696 - 8 2026-07-10
RPA3639 Republic Airlines 8 2026-07-19
RPA3583 Republic Airlines 8 2026-05-17
RPA3714 Republic Airlines 7 2026-05-13
RPA3476 - 7 2026-07-02
RPA3629 - 6 2026-07-16
RPA3536 Republic Airlines 6 2026-05-17
RPA3532 - 6 2026-07-03
RPA3519 - 6 2026-07-16
RPA3468 - 6 2026-07-01
RPA3447 - 6 2026-07-06
RPA3425 Republic Airlines 6 2026-05-24
RPA3707 - 5 2026-06-29
RPA3706 Republic Airlines 5 2026-05-14
RPA3673 - 5 2026-07-05
RPA3663 Republic Airlines 5 2026-07-22
RPA3650 Republic Airlines 5 2026-07-26
RPA3617 - 5 2026-07-13
RPA3612 - 5 2026-07-22
RPA3587 Republic Airlines 5 2026-07-25

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA3699 EWR → ATL Jul 26, 21:20 UTCJul 26, 22:15 UTC55m
2026-07-26 RPA3650 EWR → CLT Jul 26, 17:52 UTCJul 26, 20:02 UTC2h 10m
2026-07-26 RPA3650 EWR → CLT Jul 26, 17:40 UTCJul 26, 19:50 UTC2h 10m
2026-07-26 RPA3715 EWR → YUL Jul 26, 14:40 UTCJul 26, 15:35 UTC55m
2026-07-26 RPA3514 STL → EWR Jul 26, 12:55 UTCJul 26, 13:45 UTC50m
2026-07-26 RPA3551 BOS → EWR Jul 26, 09:55 UTCJul 26, 11:10 UTC1h 15m
2026-07-26 RPA3622 STL → EWR Jul 26, 02:25 UTCJul 26, 03:30 UTC1h 5m
2026-07-26 RPA3622 STL → EWR Jul 26, 02:23 UTCJul 26, 03:30 UTC1h 7m
2026-07-25 RPA3543 HAV → EWR Jul 25, 22:28 UTCJul 25, 23:30 UTC1h 2m
2026-07-25 RPA3543 HAV → EWR Jul 25, 22:20 UTCJul 25, 23:35 UTC1h 15m
2026-07-25 RPA3609 YOW → EWR Jul 25, 20:05 UTCJul 25, 20:45 UTC40m
2026-07-25 RPA3708 ORF → EWR Jul 25, 17:20 UTCJul 25, 18:35 UTC1h 15m
2026-07-25 RPA3587 EWR → GSO Jul 25, 14:45 UTCJul 25, 15:55 UTC1h 10m
2026-07-25 RPA3503 CLT → EWR Jul 25, 10:05 UTCJul 25, 11:55 UTC1h 50m
2026-07-25 RPA3428 CMH → EWR Jul 25, 01:15 UTCJul 25, 02:35 UTC1h 20m
2026-07-24 RPA3654 EWR → ROC Jul 24, 22:05 UTCJul 24, 23:10 UTC1h 5m
2026-07-24 RPA3603 EWR → YYZ Jul 24, 20:05 UTCJul 24, 21:00 UTC55m
2026-07-24 RPA3623 EWR → ITH Jul 24, 15:50 UTCJul 24, 17:30 UTC1h 40m
2026-07-24 RPA3526 EWR → BUF Jul 24, 12:50 UTCJul 24, 14:00 UTC1h 10m
2026-07-23 RPA3287 EWR → ORD Jul 23, 20:45 UTCJul 23, 21:50 UTC1h 5m
2026-07-23 RPA3473 SAV → EWR Jul 23, 17:43 UTCJul 23, 19:17 UTC1h 34m
2026-07-23 RPA3473 SAV → EWR Jul 23, 17:45 UTCJul 23, 19:20 UTC1h 35m
2026-07-23 RPA3405 AVL → EWR Jul 23, 15:25 UTCJul 23, 16:30 UTC1h 5m
2026-07-23 RPA3405 AVL → EWR Jul 23, 15:10 UTCJul 23, 16:30 UTC1h 20m
2026-07-23 RPA3548 EWR → ITH Jul 23, 13:10 UTCJul 23, 14:15 UTC1h 5m
2026-07-23 RPA3548 EWR → ITH Jul 23, 12:56 UTCJul 23, 14:17 UTC1h 21m
2026-07-23 RPA3679 BNA → EWR Jul 23, 10:20 UTCJul 23, 11:00 UTC40m
2026-07-23 RPA3477 EWR → SAV Jul 23, 02:45 UTCJul 23, 03:40 UTC55m
2026-07-23 RPA3477 EWR → SAV Jul 23, 02:16 UTCJul 23, 03:41 UTC1h 25m
2026-07-22 RPA3691 YOW → EWR Jul 22, 22:05 UTCJul 22, 23:05 UTC1h 0m
2026-07-22 RPA3691 YOW → EWR Jul 22, 22:12 UTCJul 22, 23:00 UTC48m
2026-07-22 RPA3509 EWR → BNA Jul 22, 19:25 UTCJul 22, 20:45 UTC1h 20m
2026-07-22 RPA3663 EWR → ROC Jul 22, 15:05 UTCJul 22, 16:50 UTC1h 45m
2026-07-22 RPA3612 - Jul 22, 12:35 UTCJul 22, 13:45 UTC1h 10m
2026-07-21 RPA3287 EWR → ORD Jul 21, 19:55 UTCJul 21, 20:40 UTC45m
2026-07-21 RPA3417 EWR → JAX Jul 21, 14:26 UTCJul 21, 17:57 UTC3h 31m
2026-07-21 RPA3417 EWR → JAX Jul 21, 16:10 UTCJul 21, 18:00 UTC1h 50m
2026-07-21 RPA3604 - Jul 21, 10:30 UTCJul 21, 11:35 UTC1h 5m
2026-07-21 RPA3627 - Jul 21, 02:30 UTCJul 21, 03:20 UTC50m
2026-07-21 RPA3627 EWR → PWM Jul 21, 02:25 UTCJul 21, 03:17 UTC52m
2026-07-20 RPA3680 BGR → EWR Jul 20, 23:38 UTCJul 21, 00:34 UTC56m
2026-07-20 RPA3680 BGR → EWR Jul 20, 23:25 UTCJul 21, 00:40 UTC1h 14m
2026-07-20 RPA3454 SDF → EWR Jul 20, 21:22 UTCJul 20, 22:08 UTC46m
2026-07-20 RPA3454 SDF → EWR Jul 20, 21:10 UTCJul 20, 22:10 UTC1h 0m
2026-07-20 RPA3618 MKE → EWR Jul 20, 18:05 UTCJul 20, 19:35 UTC1h 30m
2026-07-20 RPA3588 EWR → PVD Jul 20, 15:00 UTCJul 20, 16:35 UTC1h 35m
2026-07-20 RPA3619 SAV → EWR Jul 20, 12:10 UTCJul 20, 13:15 UTC1h 5m
2026-07-20 RPA3670 EWR → GSP Jul 20, 00:05 UTCJul 20, 01:45 UTC1h 40m
2026-07-20 RPA3670 EWR → GSP Jul 20, 00:05 UTCJul 20, 01:47 UTC1h 42m
2026-07-19 RPA3484 - Jul 19, 21:50 UTCJul 19, 22:50 UTC1h 0m

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 N754YX page for operator, model, and routing details .

Mode-S AA2B21 frequently asked

What is Mode-S code AA2B21?
AA2B21 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N754YX.
Where is Mode-S AA2B21 registered?
Mode-S code AA2B21 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 AA2B21 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AA2B21, octal 52425441, decimal 11,152,161.
What flights does AA2B21 operate?
Mode-S AA2B21 has broadcast 20 distinct callsigns, including RPA3696, RPA3639, RPA3583, RPA3714, RPA3476.