Thread drift.
Back in about 1981 at BCAL Gatwick, the BAC1-11s were getting the wingtips hit by Transit vans quite regularly, so it was decided to paint the wingtips dayglo orange.
The first such painted aircraft left the hangar on a Friday. I came to work on the following Monday to see that aircraft in the hangar having a wingtip changed due to Transit van damage.
It seemed that now bright dayglo, the wingtip could not be missed.