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sensors Mode-S transponder

AC1639

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N878YE · ROBINSON R-44 Raven · operated by YANKEE HELICOPTERS LLC

Hex
AC1639
Octal
53013071
Decimal
11,277,881
Country
US
Tail
N878YE
Type
R44
No current signal · last broadcast 3h ago
Flights observed
117
Distinct callsigns
1
Country
US
Last broadcast
3h ago

Last known position

Most recent position reported by Mode-S AC1639.

Country allocation

The ICAO 24-bit address AC1639 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 1 distinct

Callsign Airline Flights Last seen
N878YE - 117 2026-07-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-18 N878YE - Jul 18, 01:20 UTCJul 18, 02:50 UTC1h 31m
2026-07-17 N878YE - Jul 17, 12:19 UTCJul 17, 12:45 UTC25m
2026-07-15 N878YE - Jul 15, 16:20 UTCJul 15, 16:45 UTC25m
2026-07-15 N878YE - Jul 15, 13:05 UTCJul 15, 13:20 UTC15m
2026-07-13 N878YE - Jul 13, 18:45 UTCJul 13, 19:15 UTC30m
2026-07-13 N878YE - Jul 13, 16:30 UTCJul 13, 17:40 UTC1h 10m
2026-07-13 N878YE - Jul 13, 14:10 UTCJul 13, 14:30 UTC20m
2026-07-13 N878YE - Jul 13, 13:00 UTCJul 13, 13:25 UTC25m
2026-07-11 N878YE - Jul 11, 19:25 UTCJul 11, 20:30 UTC1h 5m
2026-07-11 N878YE - Jul 11, 11:40 UTCJul 11, 13:05 UTC1h 25m
2026-07-10 N878YE - Jul 10, 15:45 UTCJul 10, 17:00 UTC1h 15m
2026-07-10 N878YE - Jul 10, 13:25 UTCJul 10, 13:50 UTC25m
2026-07-10 N878YE - Jul 10, 10:30 UTCJul 10, 11:05 UTC35m
2026-07-09 N878YE - Jul 9, 15:30 UTCJul 9, 16:05 UTC35m
2026-07-09 N878YE - Jul 9, 11:40 UTCJul 9, 12:05 UTC25m
2026-07-09 N878YE - Jul 9, 10:30 UTCJul 9, 11:10 UTC40m
2026-07-04 N878YE - Jul 4, 12:40 UTCJul 4, 13:40 UTC1h 0m
2026-07-03 N878YE - Jul 3, 14:25 UTCJul 3, 14:45 UTC20m
2026-07-02 N878YE - Jul 2, 10:45 UTCJul 2, 11:15 UTC30m
2026-06-29 N878YE - Jun 29, 14:54 UTCJun 29, 15:39 UTC45m
2026-06-28 N878YE - Jun 28, 19:25 UTCJun 28, 19:59 UTC35m
2026-06-28 N878YE - Jun 28, 18:10 UTCJun 28, 18:25 UTC15m
2026-06-27 N878YE - Jun 27, 19:55 UTCJun 27, 20:09 UTC15m
2026-06-27 N878YE - Jun 27, 12:29 UTCJun 27, 12:45 UTC15m
2026-06-26 N878YE - Jun 26, 16:24 UTCJun 26, 16:39 UTC15m
2026-06-25 N878YE - Jun 25, 20:09 UTCJun 25, 20:45 UTC35m
2026-06-25 N878YE - Jun 25, 17:20 UTCJun 25, 17:34 UTC15m
2026-06-25 N878YE - Jun 25, 14:55 UTCJun 25, 15:15 UTC20m
2026-06-25 N878YE - Jun 25, 12:50 UTCJun 25, 14:09 UTC1h 20m
2026-06-25 N878YE - Jun 25, 10:39 UTCJun 25, 11:10 UTC30m
2026-06-24 N878YE - Jun 24, 16:34 UTCJun 24, 17:14 UTC40m
2026-06-24 N878YE - Jun 24, 14:50 UTCJun 24, 15:09 UTC20m
2026-06-24 N878YE - Jun 24, 12:34 UTCJun 24, 13:30 UTC55m
2026-06-17 N878YE - Jun 17, 13:30 UTCJun 17, 15:25 UTC1h 55m
2026-06-16 N878YE - Jun 16, 20:00 UTCJun 16, 20:10 UTC10m
2026-06-16 N878YE - Jun 16, 16:55 UTCJun 16, 17:45 UTC50m
2026-06-16 N878YE - Jun 16, 16:10 UTCJun 16, 16:20 UTC10m
2026-06-16 N878YE - Jun 16, 14:45 UTCJun 16, 15:15 UTC30m
2026-06-16 N878YE - Jun 16, 13:34 UTCJun 16, 13:44 UTC10m
2026-06-14 N878YE - Jun 14, 21:35 UTCJun 14, 22:05 UTC30m
2026-06-14 N878YE - Jun 14, 20:45 UTCJun 14, 20:55 UTC10m
2026-06-14 N878YE - Jun 14, 17:55 UTCJun 14, 20:00 UTC2h 5m
2026-06-14 N878YE - Jun 14, 15:45 UTCJun 14, 17:20 UTC1h 35m
2026-06-14 N878YE - Jun 14, 14:15 UTCJun 14, 14:40 UTC25m
2026-06-14 N878YE - Jun 14, 01:15 UTCJun 14, 01:40 UTC25m
2026-06-13 N878YE - Jun 13, 21:50 UTCJun 14, 00:40 UTC2h 50m
2026-06-13 N878YE - Jun 13, 17:05 UTCJun 13, 21:15 UTC4h 10m
2026-06-13 N878YE - Jun 13, 12:35 UTCJun 13, 13:15 UTC40m
2026-06-09 N878YE - Jun 9, 22:45 UTCJun 9, 23:25 UTC40m
2026-06-09 N878YE - Jun 9, 18:40 UTCJun 9, 19:00 UTC20m

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 N878YE page for operator, model, and routing details .

Mode-S AC1639 frequently asked

What is Mode-S code AC1639?
AC1639 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N878YE.
Where is Mode-S AC1639 registered?
Mode-S code AC1639 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 AC1639 broadcasting right now?
No active broadcast right now. Last signal was 3h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC1639, octal 53013071, decimal 11,277,881.
What flights does AC1639 operate?
Mode-S AC1639 has broadcast 1 distinct callsign, including N878YE.