Thanks but speed tape is always showing IAS?
Indeed. I'm assuming you fly something like 280kts from 'conversion' to FL100. At CRZ 0.79 IAS will be about 245kts. At conversion you'll see the IAS flown increase from 245 - 280kts. This is what I meant by 'observing the speed tape'. There are some airlines that fly such a low CI that they descend at 250 after conversion. Less easy to see.