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Label: 4J

Description

Position report data

Examples

Airframes.io message 880996538

4J01 POSWX 0318/20 ETAD/ETAD .00318S
/POS N5043.5E01121.8/OVR 0817
/ALT 270/TFW 1342/TAS 490/SAT -032
/POS GOVEN /OVR 0835
/POS DILVI
/WND 334060/TRB /SKY DCC3

Acronyms / Codes

Code Meaning
POSWX Position and weather report
ALT Altitude in flight level
OVR Overhead point
POS Position GPS co-ordinate
SAT Static Air Temperature
SKY ?
TAS True Air Speed
TFW ?
TRB ?
WND Wind direction and veocity

TFW may be related to fuel weight, with 1342 being 134,200 LBS of fuel? Equates to just unter 61000KG which is perfectly reasonable for a tanker aircraft.

Analysis

These messages appeare to be position reports giving the current weather conditions, followed by next and future waypoints. I'd expect to see messages like this over oceanic routes but have also been appearing over land.

In the example message, 880996538, it is broken down as follows

  • 4J01 = message type 4J, subtype 01(?)
  • POSWX = position and weather message
  • 0318/20 = aircraft callsign/date (callsign not provided, defaults to aircraft registration)
  • ETAD/ETAD = departure and destination ICAOs
  • .00318S = aircraft registration
  • /POS N5043.5E01121.8 = GPS position (confirmed as accurate with ADS-B data)
  • /OVR 0817 = time overhead previous listed position (0817 UTC)
  • /ALT 270 = altitude in '000s of feet, or Flight Level. 27,000ft = FL270 (confirmed as accurate with ADS-B data)
  • /TFW 1342 =
  • /TAS 490 = true airspeed in knots
  • /SAT -032 = outside air temperature in degrees
  • /POS GOVEN= next waypoint in FMC flightplan
  • /OVR 0835 = ETA to next waypoint
  • /POS DILVI = waypoint after the next in FMC flightplan
  • /WND 334060 = wind at current point, direction in degrees and speed in knots (334 degrees at 060 knots)
  • /TRB =
  • /SKY =
  • DCC3 = checksum