If there are no clouds on the descent and you can see that fact you don't need it,
Also NAI will slow your ROD as descent idle will increase so you may have to adjust to satisfy constraints etc
Also ice accumulation does not occur at temperatures below -40 unless in a CB, By -40°C, virtually all the droplets will be frozen. The exceptions are clouds with very strong vertical updrafts, such as towering cumulus or cumulonimbus, where liquid water droplets can be carried to great heights before freezing.
Last edited by r1flyguy35; 29th November 2012 at 11:57.
Reason: Spelling :)