Heathrow repairs damaged Prisms

Jet blast is a big issue that causes prisms to become non compliant quickly.  By adding a scratch resistant sapphire coating to the prism the life can be extended dramatically.  After a study at Heathrow the engineering team found that prisms in light fitting were becoming damaged at a much faster rate than normal.  After examining the fittings and monitoring the take off activites it was found that the Jets initial thrust for takeoff was damaging the prisms at the holding area.  They contacted ALS who offer a service to re-grind the prisms and fit a new tough, scrath resistant sapphire coating to extend the life of the fitting.  Normally you can only polish and re-grind a prism three times before it is unusable so this is a great solution for the airport.