And what would happen on a wing full of ice?
- it would not be done. One trusts, incidentally, RTO, that you would not be contemplating flying anyway? It is a check AFTER wing de-icing. In 2004 Astraeus was doing the check.
The retraction to >10 degrees after landing is VITAL if there is any possibility of any accumulation of frozen stuff anywhere in the flaps. Particular area is using reverse on a snow/ice contaminated runway when it is more than possible to 'pack' the LEDs with crud. Leaving them at F15 means they will not move.