A safe system is resilient to errors. The controller made a mistake - that happens, the system should deal with it. But in this case, a crash was averted only b

A safe system is resilient to errors. The controller made a mistake - that happens, the system should deal with it. But in this case, a crash was averted only because the fog lifted. It was pure luck. Ground movement radar, a runway incursion warning system, or a different landing clearance protocol could all have provided the necessary safety buffers. When you’re up to the last “hole” in the cheese, that’s a failure.