FMS Speed reduction 737 Classic

[Olendirk]

Guys,

question: I have entered an approach, all points are in, on the GS intercept point which name ist REDGO i want to have 210/3000ft. now the controller wants me to maintain highspeed as long as possible, so i fly also 270kt below 100 or more. does the fmc and the vnav path give me still good infos about the speed reduction, i mean, is the path pointer still valid? or what do i have to enter in the fmc that im not to fast for the point, when i start reduction? what effect has it to delete the 240kt/below F100?

Thanks so much


OD

[Empty Cruise]

If you program DESC page with 270/100 and set REDGO as 210/3000, then yes, the FMC will do the trick. However, remember to put any TWC into the DESC FCST page, or all your margins are gone

Also, 210 kias for GS intercept might be a bit excessive, even for a CL - but I'm sure you're aware of this

Enjoy - best regards
Empty

[BOAC]

I have always found the FMC on the 737 vastly over-optimistic in terms of what it can and cannot do, even when correctly 'programmed'. Always worth keeping a 'weather eye' on the 3x table.

[A37575]

Always worth keeping a 'weather eye' on the 3x table.

Agree. The trick is to disconnect the automatics as soon as you see a profile problem looming and then with consummate skill place the aircraft exactly where you want it to be. Once that is done you can always re-engage the automatics if you are apprehensive about manually flying the thing - which a lot of people are, of course.

[alexban]

Let's say you want to maintain 270kt till FL70. Then reduce to 250 kt ,followed by 210 at REDGO.
You should select (in descent page ) , descent speed 270 ,speed restriction 250kt/FL70 ,and in legs page REDGO 210/3000 . This way you'll create a vertical profile and enable the FMS to create a path.If the FMS will think something is not right ,you'll get a message ,like "steep descenty after XX ' ,for ex.
To be more accurate,don't forget to fill the forecast page ,at least with some estimated wind,and qnh.
And don't believe the ones telling you the VNAV it's never working ,it's just not knowing to make use of it. It's a computer, it has to have corect in-data to give correct output.

[Stanley Eevil]

Wouldn`t it be more fun to just work it out yourself? Automation for the sake of it perhaps
I often get a descent clnc to FL200 to be level by TIGER. I don`t need an FMC to tell me when to descend and I `ve never yet been embarrassed.

[A37575]

Wouldn`t it be more fun to just work it out yourself? Automation for the sake of it perhaps

Trouble is there are pilots that simply cannot resist pressing the pretty buttons and you can pick the type by the joyful snort they give as they hit the Execcute key. Automation is their whole life in an aeroplane and without it the beads of sweat appear and hands shake in fear.