There have been some really awful avoidable crashes owing to airframe icing.
The manuals talk about the importance of a proper inspection of the aircraft's surfaces, yet in my experience there were never steps provided on the ramp during icing conditions, with which to check the upper wing surfaces. One had to do a visual check from an aircraft doorway, or ask to go up the refueller's steps, (which were never quite high enough to reach the upper wing surface).
I never got a satisfactory answer about whether the de-ice crews understood that, while the tops of the wings must be clear, the bottom of the THS is the important surface to be sprayed since it operates "upside down".
OMA specifies the need for a pre-take-off contamination check, Opening the locked cockpit door to check through the cabin windows with the engines running has security risks. DV windows, wing lights, and the difficulty of checking wings at night or in LVPs is not very satisfactory.
So we are left with the poor sod(s) freezing his nuts off on the de-icing rig; on his 12th aircraft on the ramp or through the de-icing bay in steadily worsening conditions. Is he able to give a truly objective report, and did he do all the wings, or did he miss one out? Is his eyesight annually tested?