CRZ descend

[Olendirk]

Good morning!

I have a question concerning the B737-800NG: How do you guys handle a crz. descend e.g. from FL410 to 390 without using the VS feature? What are you programming in the FMC and does the aircraft descend on CRZ speed when doing that?

2.Do you have some hints and tricks about when to extend flaps to fly a nice and clean pattern?sometimes flaps are extended too early

thanks for your help!

OD

[mbcxharm]

Dial new cruise altitude up on the mode control panel then in the FMC go to the cruise page and replace the cruise altitude there with the new one too. A cruise descent is the result...

There are lots of methods people have for ensuring a nice, efficient continuous descent. Some people use gates (e.g. I want to be at 10000ft with 40nm to go to touchdown at 250 kts) and program the FMC accordingly. I must admit, I am an FMC fan - so I program that so that what it says in the box is as close to what I'm going to do as possible, and then back it up with my mental gates. The most common gates I've encountered are:

40nm - 10000ft AAL - 250kts
20nm - 6000ft - flaps up manoeuvring speed.
15nm - 4500ft - starting to stick some flaps out.
10nm - 3000ft - flap 5 manouevring speed(ish).

In practice this is a slightly on the 'getting it stable early' side of things compared to an idle thrust descent to a few hundred feet. But it doesn't work too badly.

Or when you say 'pattern' do you mean the aerodrome circuit?