LNAV/VNAV Approach.
Was watching a VOR/DME App. flown in LNAV/VNAV. The pilot was flying with speed intervention selected, he then closed the window and the a/c started accelerating to 250 knots, after which he reselected speed intervention.
Does anybody know when the approach is activated? ie distance from the initial approach point. I cannot find it in the books.
Apart from inserting a lower speed into the FMS are there any other methods from preventing this happening.
If for instance changing modes from LVCH to VNAV and the a/c is being flown at 210kts clean, once VNAV is selected the a/c again wants to accelerate to 250 kts making it look very untidy.
Would appreciate any opinions.