Wing icing recognition NG
 

I would like to ask experienced 737 pilots about your wing icing recognition techniques.
For the engine anti-ice is pretty straightforward - temperature less than 10C, visible moisture, the TAi goes on.
With the wing anti-ice it seems more difficult, however.
How do you actually see the ice forming on the leading edge of the wing?
Unless there is serious icing building up on the leading edge it seems very difficult to recognize given the shiny appearance of the leading edge...
Flying in dense cloud does not help either as one can barely see the wing anyway, even with the wing ice light on.
It seems that the best technique would be to watch the windshield wiper nut for ice buildup which would most likely be representative of what is happening on the wing..?
Also, parts of the windshield ice-up faster, so this could tell us that the conditions warrant the use of wing anti-ice...
I would appreciate your experience with that issue.
D

I think you answered your own question mate.

What you really need is something like Marinvent's Airfoil Performance Monitor...
The only device to tell you the margin remaining to the stall on a contaminated wing.

Painted black area
 

Norwegian has a black painted area just inboard of the outboard slat section. Think it was originally something Braathens just to do. Makes it real easy to see if ice is forming.
(I does require regular touch-up paint as worn black paint looks just like ice:hmm:)

Photos: Boeing 737-8JP Aircraft Pictures | Airliners.net

Indeed, I noticed that on the Norwegian leading edge...
Thanks for your input
Dan

And some smart corporate operators, which shall remain unnamed:p, have perfected the good idea from Braathens. The black painted area is extended to cover approx 6" of the unheated outboard leading edge slat, as well as the adjoining heated slat. Very easy to detect if any ice accumulation remains on the leading edge after WAI application.
Any windshield frame ice or wiper nut accumulation = wing ice. More so on the NG than CL, due to the smaller radius leading edge wing design.

Chris Brady's site is a great resource:

Ice & Rain

Note that you can see ice under the windscreen wiper in gin-clear conditions due to water collection under the blade and ambient air temperature. So it's not a useful indication of airframe icing. The centre of the windscreen is a great indication of rapidly accumulating airframe icing and it will be more obvious than the wiper bolt if the onset is rapid and severe (in such cases, the wing leading edge may not even be visibile from the flightdeck due to the thickness of the cloud).

Dense clouds and TAT between -4 and +3 are almost a guarantee for wing icing, on all types.
Be VERY careful regarding the wiper bolt " trick". Wing icing will occur while the bolt is clean. it is NOT a good indicator. if there is ice crystal accumulation on the lower part of the central windscreen, there is indeed icing on the leading edge, but again, be careful. When in clouds and in temperatures around Freezing TAT, Wing icing is possible and wing lights should be ON and leading edge checked visually every minute.

All too often do I see too much trust in this "wiper nut" method which is absolute tosh.

I agree, have very often seen ice form on the wings without anything at all on the wiper or the wiper nut.

What is necessary is care in how WAI is used. It is not an anti-ice, primarily. It is similar to the rubber boot principle. De-icer. In many companies I've been with there has been very little guidance given, and the young F/O's were ever so quick to be seen to be doing something and checking all the time, and wanting to play with switches at every opportunity.

Don't get me started on fuel balancing.

Experience ;)

Rat 5, indeed very important. it is a de-icing not anti- icing in principle. however, in heavy Icing, wing anti ice IS on regardless of accumulation on my flight, except on final approach. ( due performance)

And indeed, do not get me started on fuel balancing...and switching a notoriously prone to fail crossfeed...