I'm surprised engine runup guards haven't already been mandated. They'll add costs, sure, will require new procedures, and add risks of nacelle damage, but it appears the industry is at this point.
Delta Flight 1111 was taxiing to the gate ...
Hard to put anti-personnel screens on operational aircraft that are taxiing to and from runways.
stop the Diversity hires rather than putting safety cages around planes...duh.