Originally Posted by LeadSled
[We can measure risk, and to use a hackneyed phrase, "if you can measure it, you can manage it".
The construction of the obstacle clearance envelopes in Doc. 8168, and the lower minima possible, compared with earlier PANS-OPS editions, all have a risk analysis foundation, not "safe or not safe" as a design criteria.
From the accident record, it is clear that dive and drive is a serious issue, so a constant descent path decreases the risk of a CFIT and has the bonus of being a stable approach, without question (although some probably will) much preferred in any aircraft, but particularly heavy transport aircraft.
There is no such thing as "safe", only risk minimization, in one form of analysis defining a range of risk levels, titled ALARP -- As Low As Reasonably Practical.
You cannot avoid that at some moment that natural, direct idea is popping up in the approaching pilot's mind : which will the minimum probable distance to the ground be the next minute.
D&D brings the immediate answer : margin x K€[1,2].
CDA does NOT bring an immediate answer.
It is a derivate data like these computing engineers like to put in their algorithms : SS position, autotrim position, etc because you decrease the time delays and the computer compute that very easily.
The pilot's brain gets able to do it too if you teach him TRANSIENT piloting with AEOBATICS. Hand flying gets brain flying.
If you do not train aerobatics>transient piloting the mind is late and far behind the system and the CDA path : the pilot is no more able to answer easily to that question : am I ground safe? The pilot is no more able to measure the risk, and he is going very stable and comfortabily to the death under the limit.