Initiating Descent

[macca22au 30]

I always seem to have trouble getting the plane to start descent.  If I use speed mode it just won't initiate until I use VS to begin, then switch over to Speed mode. Naive question, but how is the descent commenced in this mode?

I have read and re-read the tutorial and the manual, but it is easy to miss items even with Ctrl+F.

[Ben F. 8]

You must reduce the throttle in speed mode, speed mode is not a vnav system and all it does is pitch to maintain that airspeed. So if you are at cruise power and hit speed mode it wont do much.

[blahhh 41]

Note that is better to have a stbilized speed when you engage the speed mode then decrease thrust.

[Cheyenne Chief Pilot 829]

Maybe it's too obvious to state, but of course you need to dial in a lower altitude.

 

So, combining all the answers to your question:

1. Have your throttles at cruise setting
2. Set a lower altitude on the FCP
3. Engage speed mode
4. Check that your target speed is appropriate for your descent (check the FMA), adjust on the FCP if necessary
5. Reduce your thrust setting to achieve the desired rate of descent (or try to catch Snowflake )

[musefan 363]

Actually, you don't even need to engage speed mode to initialise the descent. Just roll back the altitude and reduce thrust. You should start descending.

[Cheyenne Chief Pilot 829]

From the RW FCOM:

"After capturing preselected altitude (altitude track), if preselect altitude is changed, altitude hold is automatically selected and altitude preselect rearmed."

 

So you wouldn't start descending before you're stalling.