Capn Bloggs:
As for altitudes, it is obvious that 3" per hundred doesn't work: If you're circling at 500ft, you're not going to turn at 15" and if you have any hope of getting wings level by 500ft on final on a 3° slope.
My airline solved that quite cleverly. We have 3 "gates" for stabilized approach written into our procedures.
1)
First gate is the industry standard 1000 feet. However, it is defined as the aircraft has to be
on correct flight path + all the usual standard established criteria.
For an ILS it means everything has to be completed (final configuration, checklist complete, aligned with the runway), because it's appropriate for the type of approach.
For a flying a visual approach, the aircraft has to be configured and checklist completed at 1000 feet according to the above, but doesn't have to be aligned with the runway, as long as it is
on correct flight path.
2)
At 500 feet, a visual approach must additionally be aligned with the runway centerline.
Specifically for circling, landing flap and completion of landing checklist must be completed as well. Still we only have to be on correct flight path. Which at this point is doing the inbound turn.
3)
Last "gate", for circling only, is at 300 feet where it must be aligned with the centerline.
It doesn't mean that our established criteria for circling is 300 feet. The respective criteria for each previous gate has to be met as well.
In my case minimum EU OPS circling altitude is 600 feet and not 500. So to do a calculation if 3 sec
pr 100 feet
pr. MDH would be possible:
3 x 6 = 18 secs at 160 knots (82 m/s) = ca. 1500 meter = ca. 0.8 nm downwind = ca. 0.8 nm final.
So we have the inbound turn to descent 300 feet and roll out at 300 feet at 0.8 nm inbound or on approx. 3.5 deg final descent angle.
That said, it is theory. I can't think of any fields in our structure with 600 feet minima. The lowest I can find during a quick search is 730 feet AGL. Mostly, our problem is that the circling height is in the area of 1000-1200 feet, which makes it difficult to stay within 3000 meter of the airport. The most ridiculous example is an MDH of 2200 feet but still with 2400 meter visibility required and that with additionally a field elevation of almost 3500 feet. Common sense required.
