This is where training and experience start to play a part in flight
planning...

If the temperature spread between the air temperature and the "dew"
point get close (like only 3 deg difference) the possibility of the
moisture in the air causing ice at or close to freezing temps becomes
a factor. In air pilot reports (PIREPS) are useful as well. This
information is obtained when you look at the weather forcast for your
intended route, and get a weather briefing from the weather people
before flight.

We have had several days of this here, temps +3 on the ground,- 5 at
alt, dew point -1 on the ground.

Last weekend we had this, and a PIREP from a Dash 8 reporting
moderate Rime Ice decending thriugh 6000 2 hrs earlier...

Ugh!

Dave




On Wed, 29 Nov 2006 23:05:23 +0100, Mxsmanic
wrote:

B A R R Y writes:

Ice protection isn't always needed when it's cold, you also need
moisture to create ice.

But without a measurement of humidity on board, how do you know if
there's moisture out there (apart from the obvious case of visible
clouds or fog)?