Interesting discussion on timing on NPAs. Never, in 27 years of jet NPAs have I ever used timing to get to the MDA on-slope. In the brief, we'd agree on a DME distance/Altitude scale (with adjustment for the position of the DME
). True stabilised approaches/CDAs in the early 80s.
If there was no DME available, we'd simply comply with the chart altitude limits and steam on in at MDA until either we got Visual (circle if necessary) or got to the aid and did a go-around.