All,
The Reference Ground Speed approach method did originate with one thinking Captain in the old Flying Tigers, was picked up by a like minded Training Captain in Qantas, and it became “policy” in both airlines. It took them both years to break through the "conventional wisdom".
It is simplicity in itself, in planning an approach, and being aware of potential windshears, before you get there. You do need some form of ground speed readout, you don’t need IRS.
A RGS approach is actually a constant energy approach, if you think about it. Some of the formula mentioned made it look complicated, it is not, and it is only a trend indication.
All you are doing is figuring out, roughly, what your GS will be over the fence, based on reported wind and your TAS ( but at SL, unless it is stinking hot, the difference between IAS and TAS is not worth worrying about) Then, with a headwind, just fly the GS, with weather eye on the IAS. If the wind gradient from where you are to the lesser on the ground is uniform, the result will be almost constant power, as the IAS drops of, with the changing wind component ( no , I haven’t got it wrong) so the as you approach the threshold the IAS will have reduced to Vref+5 or whatever you use. Down the glideslope you will have gradually increased the nose attitude to maintain the approach slope, as the IAS decreases.
The value with microbursts is that you become very ground speed conscious, and generally you have to fly into a microburst to fly out ( Delta 1011 at ?? Dallas) and if you have a sudden increase in GS with cells around, you are headed into one, get the hell out.
If you only get hit with the increasing tailwind, with the RGS you might at least start off with a bit higher IAS than the usual from the traditional Boeing/Douglas half the steady wind plus the gust to max 20Kt additive. And thus a better chance of recovery.
Any of you who have flown the EA Kennedy wind shear profile in a sim. will remember that it was quite subtle, but still deadly.
Believe me, the RGS ground speed awareness is a life saver.
Tootle pip!!