Reported speed

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milairuk
Posts: 34
Joined: Wed Apr 09, 2014 8:12 pm
Location: Chelmsford, Essex

Reported speed

Post by milairuk » Thu May 08, 2014 6:53 pm

Does VR data show indicated airspeed or ground speed ? Whenever I hear A/C reporting their speed it never agrees with my display, whereas the FL and heading is normally almost spot on ?

John

jonfear
Posts: 365
Joined: Sat Feb 09, 2013 12:15 pm
Location: Wick St Lawrence
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Re: Reported speed

Post by jonfear » Thu May 08, 2014 7:37 pm

Hi John

I think it is ground speed but I am sure Andrew will correct me if I am wrong!

Jon
http://www.360radar.co.uk, the new name for MLAT Radar in the UK and Western Europe.

Former PP feeder Bm. No longer feeding. I do not have time to sort out imaginary problems with NTP
when it has been working fine for 2+ Years.

milairuk
Posts: 34
Joined: Wed Apr 09, 2014 8:12 pm
Location: Chelmsford, Essex

Re: Reported speed

Post by milairuk » Fri May 09, 2014 6:27 pm

Thanks Jon,

Still a bit strange as A/C inbound to EGLL via LAM seem to vary the speed difference reported in VRS even when close to each others altitude and location. I appreciate that at high altitude the IAS will not be correct, but in the descent it should be more accurate. But I'm guessing the ADSB data is GPS derived ??

John

milairuk
Posts: 34
Joined: Wed Apr 09, 2014 8:12 pm
Location: Chelmsford, Essex

Re: Reported speed

Post by milairuk » Sat May 10, 2014 4:25 pm

Yep, it's Ground Speed, been studying the LAM hold and with the strong westerly wind the downwind legs are certainly gaining speed !!

agw
Posts: 2241
Joined: Fri Feb 17, 2012 3:20 am

Re: Reported speed

Post by agw » Sun May 11, 2014 1:27 am

It's usually ground speed, although some aircraft will transmit IAS or TAS. I detect the speed type transmitted if you're using a raw feed format and that gets sent to the web site - but I don't actually show it :) I'll add the display of the speed type to the list of things to do.

milairuk
Posts: 34
Joined: Wed Apr 09, 2014 8:12 pm
Location: Chelmsford, Essex

Re: Reported speed

Post by milairuk » Sun May 11, 2014 9:12 am

Thanks Andrew, just another one on the list then !! Probably been asked before but could you add the VOR's and possibly NDB's locations to the map ??

Thanks

John

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