Originally Posted by
SJUAMMF
As I have stated above, airspeed is same as ground speed for our purposes. Of course some aircraft such as high performance fighters can go vertical. In that case ground speed is almost zero. For our practical purposes during cruising, the airplane is traveling mostly horizontal, thus airspeed is same as ground speed.
You're still not getting it.
Airspeed = how fast an object is travelling in relation to the air surrounding it.
Groundspeed = how fast an object is travelling in relation to the ground.
These can only differ from eachother if the air is moving in relation to the groud, in other words there is wind.
What you described as true air speed is what airspeed is. True airspeed is a term used to distinguish it from e.g. indicated airspeed, which is basically what the gauge it the cockpit is telling the pilot (and which differs from true airspeed mainly due to air pressure). However, I really don't want to go into that, as long as you can grasp the difference between airspeed and groundspeed.
A jet travelling with an airspeed of 500mph in a tailwind of 100mph has a ground speed of 600mph and in a headwind of 100mph the groundspeed is 400 mph . And this definately does make a difference for our purposes as it makes hours of difference in the travel time on a long haul flight.
The direction of travel makes no difference, so a fighter diving directly towars the earth at 500 mph still has a ground speed of 500 mph, because it has a speed of 500 mph in relation to the ground, just as a plane on level cruising of 500 mph has. The fighter just has more vertical speed.
or..
If you're standing in your backyard in a 30 mph wind, you have an airspeed of 30 mph, and a ground speed of 0 mph.