Hi Dave, Unfortunately 'Air-Speed' is an absolute concept, it is the speed at which air molecules pass a certain point.
It is only because we use a Pitot driven device that the terms TAS, IAS, and CAS have come about, to get over the deficiencies of the ASI.
Surely all we need to know is the Air-Speed, and wind velocity to work out our Ground Speed, to tell us how long our journey will take.
.