Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

AC1951

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N879RW · EMBRAER ERJ-170-100 · operated by DELTA AIR LINES INC

Hex
AC1951
Octal
53014521
Decimal
11,278,673
Country
US
Tail
N879RW
Type
E170
Broadcasting now · callsign RPA5643 · 32,000 ft
Flights observed
610
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:40 UTC

Current position

AC1951 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address AC1951 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
RPA5694 Republic Airlines 20 2026-07-26
RPA5637 Republic Airlines 20 2026-06-11
RPA5705 Republic Airlines 17 2026-07-24
RPA5691 Republic Airlines 17 2026-07-26
RPA5686 Republic Airlines 17 2026-06-16
RPA5643 Republic Airlines 17 2026-07-24
RPA5661 - 14 2026-07-14
RPA5799 Republic Airlines 13 2026-07-24
RPA5715 Republic Airlines 13 2026-05-29
RPA5610 Republic Airlines 13 2026-06-01
RPA5825 Republic Airlines 12 2026-07-26
RPA5818 - 12 2026-07-20
RPA5794 Republic Airlines 12 2026-06-11
RPA5719 - 12 2026-07-14
RPA5642 - 11 2026-07-16
RPA5618 - 11 2026-07-19
RPA5590 - 11 2026-07-19
RPA5830 - 10 2026-07-19
RPA5806 - 10 2026-07-12
RPA5664 - 10 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA5825 DCA → LGA Jul 26, 19:50 UTCJul 26, 21:40 UTC1h 50m
2026-07-26 RPA5694 MVY → LGA Jul 26, 17:35 UTCJul 26, 18:40 UTC1h 5m
2026-07-26 RPA5694 MVY → LGA Jul 26, 14:40 UTCJul 26, 15:35 UTC55m
2026-07-26 RPA5691 BOS → LGA Jul 26, 12:05 UTCJul 26, 13:30 UTC1h 25m
2026-07-26 RPA5691 BOS → LGA Jul 26, 12:05 UTCJul 26, 13:30 UTC1h 25m
2026-07-25 RPA5675 ORD → BOS Jul 25, 22:45 UTCJul 26, 00:05 UTC1h 20m
2026-07-25 RPA5723 CLT → LGA Jul 25, 18:55 UTCJul 25, 21:00 UTC2h 5m
2026-07-25 RPA5723 CLT → LGA Jul 25, 14:45 UTCJul 25, 16:25 UTC1h 40m
2026-07-25 RPA5811 JFK → BUF Jul 25, 12:15 UTCJul 25, 13:05 UTC50m
2026-07-25 RPA5676 LGA → DCA Jul 25, 01:40 UTCJul 25, 03:00 UTC1h 20m
2026-07-24 RPA5746 JFK → CLT Jul 24, 23:15 UTCJul 25, 00:05 UTC50m
2026-07-24 RPA5746 JFK → CLT Jul 24, 23:13 UTCJul 24, 23:58 UTC45m
2026-07-24 RPA5767 BOS → JFK Jul 24, 21:15 UTCJul 24, 22:00 UTC45m
2026-07-24 RPA5767 BOS → JFK Jul 24, 18:40 UTCJul 24, 19:20 UTC40m
2026-07-24 RPA5643 BOS → PIT Jul 24, 15:50 UTCJul 24, 17:30 UTC1h 40m
2026-07-24 RPA5643 BOS → PIT Jul 24, 15:49 UTCJul 24, 17:23 UTC1h 34m
2026-07-24 RPA5643 BOS → PIT Jul 24, 13:10 UTCJul 24, 14:55 UTC1h 45m
2026-07-24 RPA5799 LGA → BOS Jul 24, 10:35 UTCJul 24, 11:25 UTC50m
2026-07-24 RPA5705 LGA → JAX Jul 24, 02:55 UTCJul 24, 03:45 UTC50m
2026-07-23 RPA5825 DCA → LGA Jul 23, 23:15 UTCJul 24, 01:00 UTC1h 45m
2026-07-23 RPA5825 DCA → LGA Jul 23, 23:10 UTCJul 24, 00:47 UTC1h 37m
2026-07-23 RPA5825 DCA → LGA Jul 23, 19:50 UTCJul 23, 21:50 UTC2h 0m
2026-07-23 RPA5694 MVY → LGA Jul 23, 17:25 UTCJul 23, 18:25 UTC1h 0m
2026-07-23 RPA5694 MVY → LGA Jul 23, 15:15 UTCJul 23, 16:15 UTC1h 0m
2026-07-23 RPA5772 BOS → MCI Jul 23, 12:55 UTCJul 23, 13:35 UTC40m
2026-07-23 RPA5687 BOS → DCA Jul 23, 10:15 UTCJul 23, 11:35 UTC1h 20m
2026-07-23 RPA5718 JFK → RDU Jul 23, 01:00 UTCJul 23, 01:50 UTC50m
2026-07-23 RPA5718 JFK → RDU Jul 23, 00:58 UTCJul 23, 01:41 UTC43m
2026-07-22 RPA5718 JFK → RDU Jul 22, 22:40 UTCJul 22, 23:30 UTC50m
2026-07-22 RPA5803 SAV → BOS Jul 22, 19:00 UTCJul 22, 21:40 UTC2h 40m
2026-07-22 RPA5803 BOS → SAV Jul 22, 15:45 UTCJul 22, 18:00 UTC2h 15m
2026-07-22 RPA5703 DCA → BOS Jul 22, 13:40 UTCJul 22, 14:40 UTC1h 0m
2026-07-22 RPA5703 DCA → BOS Jul 22, 11:10 UTCJul 22, 12:05 UTC55m
2026-07-21 RPA5619 - Jul 21, 00:20 UTCJul 21, 02:00 UTC1h 40m
2026-07-20 RPA5619 BOS → MKE Jul 20, 21:00 UTCJul 20, 23:05 UTC2h 5m
2026-07-20 RPA5668 BOS → BOS Jul 20, 19:10 UTCJul 20, 19:15 UTC5m
2026-07-20 RPA5668 - Jul 20, 18:00 UTCJul 20, 19:15 UTC1h 15m
2026-07-20 RPA5668 BWI → BOS Jul 20, 17:59 UTCJul 20, 18:55 UTC56m
2026-07-20 RPA5668 BOS → BWI Jul 20, 16:05 UTCJul 20, 17:15 UTC1h 10m
2026-07-20 RPA5785 LGA → BOS Jul 20, 14:14 UTCJul 20, 14:55 UTC41m
2026-07-20 RPA5785 LGA → BOS Jul 20, 14:15 UTCJul 20, 14:55 UTC40m
2026-07-20 RPA5874 BOS → MCI Jul 20, 11:45 UTCJul 20, 13:00 UTC1h 15m
2026-07-20 RPA5874 BOS → MCI Jul 20, 11:45 UTCJul 20, 13:10 UTC1h 25m
2026-07-20 RPA5818 - Jul 20, 01:15 UTCJul 20, 02:40 UTC1h 25m
2026-07-19 RPA5590 - Jul 19, 21:50 UTCJul 19, 23:25 UTC1h 35m
2026-07-19 RPA5590 HHH → LGA Jul 19, 21:46 UTCJul 19, 23:21 UTC1h 35m
2026-07-19 RPA5830 - Jul 19, 19:35 UTCJul 19, 20:15 UTC40m
2026-07-19 RPA5817 - Jul 19, 16:35 UTCJul 19, 17:15 UTC40m
2026-07-19 RPA5618 - Jul 19, 14:00 UTCJul 19, 15:35 UTC1h 35m
2026-07-18 RPA5599 - Jul 18, 11:30 UTCJul 18, 12:55 UTC1h 25m

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 N879RW page for operator, model, and routing details .

Mode-S AC1951 frequently asked

What is Mode-S code AC1951?
AC1951 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N879RW.
Where is Mode-S AC1951 registered?
Mode-S code AC1951 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 AC1951 broadcasting right now?
Yes. Mode-S AC1951 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC1951, octal 53014521, decimal 11,278,673.
What flights does AC1951 operate?
Mode-S AC1951 has broadcast 20 distinct callsigns, including RPA5694, RPA5637, RPA5705, RPA5691, RPA5686.