Jump to content

Sign in to follow this  
johndrago

Descent Phase - What Am I doing Wrong Part II - 747

Recommended Posts

I understand that if I change the altitude on the MCP while in VNAV cruise, the plane will start it's descent to the new altitude at the TOD.However...Since I'm using FS ATC, they usually start my descent 50 miles before TOD. What I do now is dial the new altitude in the MCP, and click the center of the ALT knob to start the VNAV descent. What I'm finding is that the engines retard quickly, and when the 747 starts it's descent, it begins very steeply to makeup for the speed it's trying to catch up to (like FLCHG).What's the proper procedure to initiate a VNAV descent when starting before the TOD?Thanks in advance,John


Boeing777_Banner_Pilot.jpg

 

- John Drago

Share this post


Link to post

Use the DES NOW function on VNAV pg 2. What you are doing there by using alt int is trying to lower your crz altitude since that will set the MCP altitude as the crz altitude-something you cannot do in CRZ without starting an early descent (true you are wanting to descend but this is not the procedure to accomplish this). You can also perfrom a " ACT CRZ DESCENT" which instead of using the ALT INT procedure (Pressing the ALT KNOB after resetting the MCP alt), simply reset the MCP alt and type a lower than current crz altitude into the FMC crz alt line (LSK1) and hit EXECU. You will still retain your crz phase this way. Of course you can go FLCH/V/S too (V/S perferred)... [h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|


Randy J Smith

Share this post


Link to post
Guest Just747-400

Randy,What is he doing is an early descend, if you within 50 nm of td and dial a clearance alt and press the altitude knob you should get 1250 fpm until reaching new td or new target altitude. Sorry, but vs is not the preferred method, actually many airlines teach pilots to stay out off vs as much as possible because of the potential problems involved with it. Just only 2 very important I can think off: no stall protection, no speed protection.

Share this post


Link to post

Hey Alex, I think we are not talking about the same thought here since I was referfing to the initial descent, in other words how we get to the descent phase. If he desires an "early descent" is there somewhere that states the one method is by using ALT INT to begin the descent? I know you can use it foe descents ;P. If you use ALT INT are you not stating a restrictive altitude to descend too? Plus is not DES NOW less workload than ALT INT? Des NOW removes restraints whereas you must push the alt button more than once etc. My responce was to use what Boeing states to use for an early descent, namely using DES NOW through the FMC prompt and not pushing the ALT INT button for DES NOW but hey you fly the thing :(.The way I read it, the "descend now" from using ALT INT is a result not a means of initiating an early descent inavertantly using ALT INT while in crz - lowering one's crz altitude which you cannot "achieve" with ALT INT. [h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|


Randy J Smith

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    2%
    $540.00 of $25,000.00 Donate Now
×
×
  • Create New...