Hi phnuff,
It does help alot.
Now I am sure I can explain it clearly to other people.
Thanks alot.
Two additional points need some comments:
(1) For an airspeed 65kt appeared on the ASI. Let\'s say 55 kt is contributed by the engine; and 10kt is resulted from the headwind. You mentioned that "this will be equivalent to a ground speed of less than 65 kt".
To be more precise, can I say that the ground speed should be below 55 kt? Because the only forward speed is 55 kt. And the headwind should reduce the ground speed of the aircraft somewhat. Correct me if I am wrong.
(2) I now understand tailwind reduces the airspeed of an aircraft and consequently reduce lift. But why do the airline pilots try to fly with the jetstream? Which one do pilots prefer for the same thrust provided by the engine, a higher groundspeed (tailwind) or a higher airspeed (headwind)?