Originally Posted by
Fareastdriver
How do you do that without a subscale?
The altimeter had a lubber line which we were told was the SPS setting. It was probably calibrated to ICAN.
It doesn't matter whether you use QNH, QFE or bouncing pingpong balls, the glideslope is still the same. . . I flew my first precision approach (ILS) in 1962.
Who mentioned precision approach? ACR7, Eureaka or whatever were azimuth only approaches. Watching blips on CRTs was dificult enough without having to add the range/height value to airfield elevation and then check with the altimeter.
Just a thought and it fits with the philosophy that 'we DO QFE' having forgotten WHY we do QFE.
I am not suggesting my proposal is the correct reason just that it is a possible reason.