At low levels, IAS=TAS (because the pressure at the low level has not fallen significantly from ISA, hence the two are roughly similar)
Soo..At 2000' the headwind is 50 kt. You are maintaining 150kt (say) so your groundspeed is 100kt. Now say the headwind drops to 30kt. The inertia of the aircraft is still the same, so you are still doing 100kt groundspeed, but your airspeed drops to 130kt. Solution POWER (sorry, thrust!) to recover back to your chosen speed. You may dip below the glideslope for a short mo as well.
This is the reason behind adding a few knots to Vref, so that when your speed drops, it should not drop below you minimum approach speed. This is why putting it on the ATIS helps, as we are able to plan for it.
CCCCCoooo...ugh
[This message has been edited by Cough (edited 18 May 2001).]