I would like to know which is the velocity, TAS, CAS ?
Interesting question - I assumed it was ground speed.
The other values are only useful if you are trying to fly the aircraft.
Could you give some more context to your question?
TAS is true airspeed
CAS is calibrated airspeed.
IAS is indicated airspeed.
TAS is the actual velocity of the air relative to the aircraft.
Maybe read this wikipedia article: https://en.wikipedia.org/wiki/Indicated_airspeed
Ground speed is obviously TAS plus wind.
Now if you are asking which speed is normally displayed on tracking sites: Ground speed.
If other speeds are displayed they are normally declared as such, for example in SkyView:
Groundspeed: 368 kt
IAS: 245 kt
TAS: 452 kt
Mach Number: 0.776
The “Speed” in the mouseover box / tooltip is the ground speed.
Yes, in fact I was asking which speed was displayed on this tracking site. How would you know that on this site it is the ground speed?
The speed over ground is usually the most relevant value in regards to tracking aircraft.
It is also the only speed that was transmitted in the initial version of ADS-B.
You mean flight tracking like this on flightaware correct: https://flightaware.com/live/flight/DLH400
Because many on this forum supply the data and have a local map with additional details of the aircraft they are receiving.
But as far as i know all speeds used on the flightaware and other tracking sites are ground speeds unless stated otherwise.
I can confirm this for planes that fly overhead because i can check their data directly and compare it to the tracking site.
Speeds shown on the flightaware.com flight page & tracklog page are indeed groundspeeds.
The statement above is backwards.
TAS is the actual velocity of the aircraft relative to the air around it.