Originally Posted by Centaurus
Thanks for the replies from which one can deduce that the FCTM recommendation (at page 4.14 of my copy) which states clearly "Normal descents are made in the clean configuration to pattern altitude or instrument approach altitude." is unrealistic nonsense and Boeing should know better.
There's nothing wrong with that statement, just with your interpretation of it. Nowhere does the FCTM say flap selection should be done in level flight (the recommendation reads "flight
to XYZ altitude", not "flight
at XYZ altitude"). This is just a recommendation to stay in clean configuration as long as practically possible, i.e. until reaching the pattern altitude or instrument approach altitude. That corresponds with another FCTM recommendation, one page earlier:
Plan the descent to arrive at traffic pattern altitude at flaps up manoeuvring speed approximately 12 miles from the runway when proceeding straight-in, or 8 miles out when making an abeam approach.
The "Descent Planning" and "Descent Rates" chapters provide some pretty useful guidelines and reference data to optimise the descent and deceleration planning.
Originally Posted by Centaurus
Interestingly, on the same page Boeing say "Avoid using the landing gear for increasing drag. This minimises passenger discomfort and increases door life." Seems this is unrealistic nonsense too...
Again you seem to misinterpret the FCTM, possibly due to the somewhat ambiguous wording by Boeing. "Avoid" in this sentence is clearly meant as a recommendation, because just a couple of lines earlier the FCTM states:
When thrust requirements for anti-icing result in less than normal descent rates with speedbrakes extended, or if higher than normal descent rates are required by ATC clearance, the landing gear can be lowered to increase the rate of descent.
Boeings recommendations are certainly not unrealistic nonsence, but simple common sense, and applicable in the vast majority of approaches. I agree that using flaps as speedbrakes is not a great idea, and so does Boeing:
The flaps are normally not used for increasing the descent rate. Normal descents are made in the clean configuration to pattern or instrument approach altitude.
Note: "normally", not "never". Flying with flaps extended just below placard speed is not a sensible thing to do in general, but if it's necessary it's necessary. The same goes for early gear extension.