Originally Posted by
Discorde
Because if you’re distracted during high workload conditions you may forget to reset QNH. Or you may mis-set it.
Most countries do not use QFE.
In the not too distant future altimetry will be GPS based and altimeter setting (and mis-setting) will be a thing of the past.
The RAF do not use actual QNH except at Odiham and Northolt where both airflelds are under the LTMA, but having said that, Odiham circuit heights are on QFE.