Quid
I think I broadly agree with you! Please excuse the nitpicking that follows!
You say
1. “The a/c flies in the relative wind. Responses to control inputs will be no different until some "ground based" reference is used.”
I say
Yes but TAS is a ground based reference.
When I was a very youg lad I was taught to do loops at moderately low levels in a Vampire. I was then made to go up to 40,000ft and do the same. Ha!. When low level there was nothing wrong with pulling up at 230 kts IAS (giving say a TAS of 250 at a sensible height above the deck) HOWEVER, try that at 40k when the aircraft had a TAS twice its IAS and you soon learned about the effects of inertia on the tendency of an aircraft to go (relatively) straight on when you applied a given force (still 230kts worth in this case)
As you rightly say moving down an ILS at two different ground speeds gives two different rates of descent that have to be reduced in the flare.
You say
2. "Ground effect" will be more pronounced with a headwind than a tailwind. In the flare that would certainly be a factor.
I say
You may well be right for a largish - say commercial aircraft. But I just have a little niggle that the wind speed just above the runway will be less than at say 100 ft (windshear due to boundary layer effects if you like) this actually reverses its effect when landing with a tailwind i.e. you finish up with less of a tailwind right at the end, so IAS in the flare will decay slower than usual – which is a tad of good news in a tailwind landing. Mind you I would not like to measure the difference in a normal real turbulent atmos would you?
You say
3. After touchdown, groundspeed will be a big factor. After touchdown, the only airfoil still "flying" is the rudder. At any given groundspeed, the effect of the headwind or tailwind will be markedly different. The rate of a/c response to rudder inputs with a 120 kt groundspeed and a 20 kt headwind will be much greater than a 120 groundspeed and a 20 kt tailwind.
To keep comparing apples to apples, when at high density altitude airports, the IAS/TAS relationship will not change with variations in headwinds/tailwinds, but the above considerations will have a marked effect.
I say
Agreed
Good to talk to you.
JF