Apparatus

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sensors Mode-S transponder

A21FA1

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N236JQ · EMBRAER ERJ-170-200 (long wing) · operated by DELTA AIR LINES INC

Hex
A21FA1
Octal
50417641
Decimal
10,624,929
Country
US
Tail
N236JQ
Type
E75L
Broadcasting now · callsign RPA5615 · 31,000 ft
Flights observed
731
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:50 UTC

Current position

A21FA1 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A21FA1 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
RPA5858 Republic Airlines 10 2026-07-25
RPA5650 - 10 2026-06-25
RPA5703 Republic Airlines 9 2026-07-26
RPA5597 - 9 2026-07-13
RPA5856 - 8 2026-07-17
RPA5808 - 8 2026-07-16
RPA5743 - 8 2026-07-17
RPA5710 - 8 2026-07-16
RPA5686 Republic Airlines 8 2026-07-01
RPA5678 - 8 2026-07-11
RPA5658 - 8 2026-06-24
RPA5649 - 8 2026-06-25
RPA5633 Republic Airlines 8 2026-07-25
RPA5596 Republic Airlines 8 2026-07-25
RPA5861 Republic Airlines 7 2026-06-13
RPA5859 - 7 2026-06-30
RPA5851 - 7 2026-07-10
RPA5850 Republic Airlines 7 2026-07-21
RPA5823 - 7 2026-07-11
RPA5779 - 7 2026-07-07

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA5591 BNA → LGA Jul 26, 20:20 UTCJul 26, 21:50 UTC1h 30m
2026-07-26 RPA5748 IND → BOS Jul 26, 18:10 UTCJul 26, 19:05 UTC55m
2026-07-26 RPA5703 DCA → BOS Jul 26, 14:50 UTCJul 26, 15:45 UTC55m
2026-07-26 RPA5703 DCA → BOS Jul 26, 12:35 UTCJul 26, 13:50 UTC1h 15m
2026-07-26 RPA5765 BOS → BNA Jul 26, 10:20 UTCJul 26, 10:55 UTC35m
2026-07-25 RPA5702 BOS → JAX Jul 25, 23:40 UTCJul 26, 00:25 UTC45m
2026-07-25 RPA5858 JFK → CHS Jul 25, 21:00 UTCJul 25, 22:10 UTC1h 10m
2026-07-25 RPA5858 JFK → CHS Jul 25, 20:59 UTCJul 25, 22:09 UTC1h 10m
2026-07-25 RPA5858 JFK → CHS Jul 25, 18:30 UTCJul 25, 19:45 UTC1h 15m
2026-07-25 RPA5596 BOS → CHS Jul 25, 14:48 UTCJul 25, 16:49 UTC2h 1m
2026-07-25 RPA5596 BOS → CHS Jul 25, 14:50 UTCJul 25, 16:55 UTC2h 5m
2026-07-25 RPA5596 BOS → CHS Jul 25, 11:25 UTCJul 25, 13:35 UTC2h 10m
2026-07-25 RPA5633 IND → BOS Jul 25, 02:10 UTCJul 25, 03:15 UTC1h 5m
2026-07-24 RPA5724 BOS → DCA Jul 24, 23:30 UTCJul 25, 00:20 UTC50m
2026-07-24 RPA5721 RIC → BOS Jul 24, 21:20 UTCJul 24, 22:05 UTC45m
2026-07-24 RPA5721 RIC → BOS Jul 24, 21:18 UTCJul 24, 21:59 UTC41m
2026-07-24 RPA5727 DCA → LGA Jul 24, 19:25 UTCJul 24, 19:55 UTC30m
2026-07-24 RPA5694 MVY → LGA Jul 24, 17:15 UTCJul 24, 18:10 UTC55m
2026-07-24 RPA5694 MVY → LGA Jul 24, 17:13 UTCJul 24, 18:06 UTC53m
2026-07-24 RPA5694 MVY → LGA Jul 24, 14:55 UTCJul 24, 16:00 UTC1h 5m
2026-07-24 RPA5660 - Jul 24, 12:20 UTCJul 24, 13:50 UTC1h 30m
2026-07-23 RPA5616 JFK → CMH Jul 23, 22:30 UTCJul 24, 00:30 UTC2h 0m
2026-07-23 RPA5600 MCI → LGA Jul 23, 20:20 UTCJul 23, 21:20 UTC1h 0m
2026-07-23 RPA5857 BOS → DCA Jul 23, 17:00 UTCJul 23, 18:25 UTC1h 25m
2026-07-23 RPA5728 LGA → BNH Jul 23, 14:40 UTCJul 23, 15:15 UTC35m
2026-07-23 RPA5625 CLT → BOS Jul 23, 11:20 UTCJul 23, 13:00 UTC1h 40m
2026-07-23 RPA5780 DCA → LGA Jul 23, 03:21 UTCJul 23, 05:10 UTC1h 49m
2026-07-23 RPA5780 DCA → LGA Jul 23, 03:25 UTCJul 23, 05:15 UTC1h 50m
2026-07-23 RPA5831 EWR → BOS Jul 23, 01:00 UTCJul 23, 01:55 UTC55m
2026-07-22 RPA5600 MCI → LGA Jul 22, 22:05 UTCJul 22, 23:05 UTC1h 0m
2026-07-22 RPA5608 LGA → BOS Jul 22, 16:25 UTCJul 22, 18:25 UTC2h 0m
2026-07-22 RPA5608 LGA → BOS Jul 22, 13:10 UTCJul 22, 15:40 UTC2h 30m
2026-07-22 RPA5734 BOS → ORF Jul 22, 11:10 UTCJul 22, 11:40 UTC30m
2026-07-21 RPA5908 CMH → PIT Jul 21, 21:10 UTCJul 21, 23:22 UTC2h 12m
2026-07-21 RPA5908 CMH → PIT Jul 21, 21:10 UTCJul 21, 23:20 UTC2h 10m
2026-07-21 RPA5845 - Jul 21, 13:40 UTCJul 21, 14:40 UTC1h 0m
2026-07-21 RPA5845 BOS → PHL Jul 21, 10:55 UTCJul 21, 12:00 UTC1h 5m
2026-07-21 RPA5850 LGA → BOS Jul 21, 00:45 UTCJul 21, 01:25 UTC40m
2026-07-21 RPA5850 LGA → BOS Jul 21, 00:41 UTCJul 21, 01:21 UTC40m
2026-07-20 RPA5719 BOS → LGA Jul 20, 22:50 UTCJul 20, 23:40 UTC50m
2026-07-20 RPA5719 BOS → LGA Jul 20, 21:10 UTCJul 20, 21:55 UTC45m
2026-07-20 RPA5661 - Jul 20, 16:40 UTCJul 20, 18:10 UTC1h 30m
2026-07-20 RPA5661 LGA → GRR Jul 20, 14:00 UTCJul 20, 15:30 UTC1h 30m
2026-07-20 RPA5873 - Jul 20, 09:55 UTCJul 20, 11:05 UTC1h 10m
2026-07-19 RPA5876 PIT → PWM Jul 19, 17:25 UTCJul 19, 17:55 UTC30m
2026-07-19 RPA5876 PIT → PWM Jul 19, 17:22 UTCJul 19, 17:53 UTC31m
2026-07-18 RPA5641 BOS → CLE Jul 18, 14:25 UTCJul 18, 15:55 UTC1h 30m
2026-07-18 RPA5641 BOS → CLE Jul 18, 14:21 UTCJul 18, 15:56 UTC1h 35m
2026-07-18 RPA5698 DCA → BOS Jul 18, 11:50 UTCJul 18, 13:00 UTC1h 10m
2026-07-18 RPA5666 BOS → DCA Jul 18, 01:15 UTCJul 18, 02:29 UTC1h 15m

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 N236JQ page for operator, model, and routing details .

Mode-S A21FA1 frequently asked

What is Mode-S code A21FA1?
A21FA1 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N236JQ.
Where is Mode-S A21FA1 registered?
Mode-S code A21FA1 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 A21FA1 broadcasting right now?
Yes. Mode-S A21FA1 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A21FA1, octal 50417641, decimal 10,624,929.
What flights does A21FA1 operate?
Mode-S A21FA1 has broadcast 20 distinct callsigns, including RPA5858, RPA5650, RPA5703, RPA5597, RPA5856.