Originally Posted by
anotherthing
I was of the opinion that a gust of wind as you mentioned would not change the IAS reading, it merely changes your True Air Speed and ground speed, therefore, we can tell if you are at 160 by 4 dme because that is what your IAS readout should say. If you are established at 160kts and you experience a 20kt gust, does this cause the IAS to change??
In the 744 we are not even presented with TAS information, only IAS. If we are established at 160kts and experience a 20kt +ve gust then yes, the IAS will rocket up to 180kts, then back down to 160kts when the gust passes. I'm not sure I understand what information your mode S readout is presenting you with. Is it the target speed we have selected (but not necessarily yet achieved) or is it the instantaneour IAS the aircraft is currently at?