737 Probe Heat ON before start-up

[Banana Joe]

Similar to mine, but would you do that with 7 or 8 degrees with visible moisture and wet taxiway and runway?

The general consensus, after I asked two pilots involved in the training department, in my company is to switch the probe heat on in freezing conditions, but the manual says to do that in icing conditions. Freezing conditions are described and referenced for the 30 second run up.

This is what raised my doubts.

[Jump Complete]

Banana Joe. 10• or less, visable moisture and / or wet runway would just be icing, and probes go during the after-start flow. It’s only when it’s 3• or less (with a wet runway etc) that it becomes defined as freezing and the probes go on before start (and we cycle the flaps fully before setting and do the run-up.)
At least in our books!
EDIT: Our manuals aren’t that clear either, and although I know it’s 3• (because we did it yesterday with a Line Training Captain) I can find the procedure but I can’t find the actual reference for the Freezing Conditions definition! Probably there somewhere, probably time to put it down and watch some rubbish on TV.

[Banana Joe]

Exactly, I agree with you after I asked to my trainers. But our book doesn't clearly specify to switch them on during freezing conditions. This is what led me into confusion until I asked for clarification.

[alikiashemshaki]

PROBLEM AFTER AD 2019-09-01

AFTER AD 2019-09-01 B737 CLASSIC PITOT PROBE burn out more than before