AirNav RadarBox
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
 


Author Topic: Question  (Read 2894 times)

0 Members and 2 Guests are viewing this topic.

Jeremy

  • Sr. Member
  • ****
  • Posts: 369
  • Jeremy
Question
« on: July 11, 2009, 10:51:28 AM »
Another question from me - I am learning fast, honest -  when tracking an aircraft the little aeroplane label is there. Sometimes I see a circle with a cross in it. What is this?
Beta V 3.0
Jeremy
G4DOQ
QRZ.com

tarbat

  • ShipTrax Beta Testers
  • Hero Member
  • *
  • Posts: 4219
    • Radarbox at Easter Ross
Re: Question
« Reply #1 on: July 11, 2009, 10:55:04 AM »
Circle/cross symbol means that Radarbox doesn't know the heading of the aircraft.  Either it's not being transmitted, or the aircraft has timed-out in Radarbox.

Jeremy

  • Sr. Member
  • ****
  • Posts: 369
  • Jeremy
Re: Question
« Reply #2 on: July 11, 2009, 12:02:56 PM »
Thanks.
Sometimes it tracks across the screen with the circle/cross so it must know the direction.
Thanks for your help.
J.
G4DOQ
QRZ.com

tarbat

  • ShipTrax Beta Testers
  • Hero Member
  • *
  • Posts: 4219
    • Radarbox at Easter Ross
Re: Question
« Reply #3 on: July 11, 2009, 12:14:18 PM »
Even though it can track the change in position, that doesn't mean the aircraft is transmitting it's heading.  Depending on wind direction, heading and direction of travel can be different.

DaveReid

  • Hero Member
  • *****
  • Posts: 1815
    • Heathrow last 100 ADS-B arrivals
Re: Question
« Reply #4 on: July 13, 2009, 08:32:30 AM »
Sometimes it tracks across the screen with the circle/cross so it must know the direction.

The majority of ADS-B-equipped aircraft transmit "velocity over ground", from which both groundspeed and track can be calculated.
 
However some (for example UAL B772s) transmit airspeed and heading instead - I assume it's these that don't show up with the aircraft symbol.
This post has been scanned for any traces of negativity, bias, sarcasm and general anti-social behaviour