Jump to content

Sign in to follow this  
macpac22

D-TO and CLB

Recommended Posts

Hi captains!i was wondering if someone could give me some tips on a derated takeoff and more importantly the climb.Ok my example was situated at EGLL , WOD2F departure off of runway 27R with Flaps 20. Now my aircraft weight sits at 362.5 approx, for this i used no weather and no wind and a default +15C temp. I used a take off performer based on my weight and calculated 52 degrees as my assumed temperature, that i inserted into the FMC. The FMC chose "CLB" as a default, which i did not change.Ok so my first point was to reach Burnham NDB at 3000ft or above. i fired down the runway and rotated nicely with enough runway to spare and began my climb. My rate of climb is pretty good at this point but when "CLB" kicks in at 1500ft the aircraft noses down to obviously increase speed to its designated climb speed and to raise the flaps. But what this does is slow my rate of climb and i always miss the BUR at 3000ft or above. I have messed around with the FMC and the only way to actually reach 3000ft or above at BUR was to enter 3000ft in the TRUST REDUCTION section in the FMC. The aircraft climbs to 3000ft still under "D-TO" mode and then at 3000ft "CLB" is actioned and the aircraft noses down and i pass the BUR 3000A no problems. I can fly the rest of the SID with no altitude problems. My question is after rotation how long can you spend in "D-TO" mode before entering a CLB thrust setting. Is what im doing actually allowed? Ive read that for noise abatement procedures an aircraft needs to be at a certain height before accelerating to climb speed. This obviously depends on the airfield. For Heathrow the ITVV B744 DVD states "at 1580ft we should see CLB 1" . I tried entering 1580ft into the thrust reduction area but still i fall short of the 3000A limit usually by around 600ft.Any ideas or info?cheers


Paul McMahon

Ireland

747400.jpg

Share this post


Link to post

Have a look at the takeoff ref page where it says flaps/accel ht at the top.If you enter 3000ft at the accel ht the acft will climb to this height before the pitch comes down for acceleration at any climb power setting.Have funJames

Share this post


Link to post

so do i leave the thrust reduction area at the default of 1500ft and just change flaps to 20/3000?


Paul McMahon

Ireland

747400.jpg

Share this post


Link to post
Guest topcat

Depending on authority regulations you can use take-off power either:- 5 minutes (all engines) or 10 minutes (one engine out)or- 10 minutes (all engines) and 10 minutes (one engine out)

Share this post


Link to post
Guest D17S

LSK 1L on the TO page is to set the acceleration altitude setting you want for the takeoff sequence and the flap setting the FMC is using for the Vspeed calculation. So it's kinda a dual indication. Flap setting and acceleration altitude. As you know, acceleration altitude is where you want the airplane to stop trying to maintain the initial V2(+?) airspeed, nose on down and accelerate to your first speed limit (probably a flap sped limit). The "20" part is just telling you the flap setting the FMC is using to calculate the Vspeeds. At LSK 3L is thrust reduction. This can be either a flap setting or an altitude. Thrust reduction and acceleration altitude are entirely separate settings and can be mixed and matched as the pilot wants. A RW 744 pilot had this to say about that. . . If I

Share this post


Link to post

Thanks for the input. Having tested it out multiple times setting LSK1 to 20/3000 works the best. I clear the SID with no problems.Many thanks


Paul McMahon

Ireland

747400.jpg

Share this post


Link to post

A standard ICAO noise-abatement departure:I think this ICAO A or B it is called or something like that:(One of them being a more severe restriction - this is the more severe one).- Hold V2+10 at set takeoff thrust- At 1500 ft, reduce thrust to climb thrust (usually CLB1 for the 744 I think) {This is THR RED ALT}- At 3000ft, begin acceleration from V2+10 to climb speed {This is ACC ALT}- Usual Engine out acceleration I think is at 1000ftI think this is the standard procedure for many airports, including London Heathrow. Anyone, please feel free to correct me.CheersRudy


Rudy Fidao

Share this post


Link to post

>A standard ICAO noise-abatement departure:>>I think this ICAO A or B it is called or something like that:>(One of them being a more severe restriction - this is the>more severe one).>>- Hold V2+10 at set takeoff thrust>- At 1500 ft, reduce thrust to climb thrust (usually CLB1 for>the 744 I think) {This is THR RED ALT}>- At 3000ft, begin acceleration from V2+10 to climb speed>{This is ACC ALT}>- Usual Engine out acceleration I think is at 1000ft>>I think this is the standard procedure for many airports,>including London Heathrow. Anyone, please feel free to>correct me.>>Cheers>Rudy>so the FMC would be set like:FLAPS : 20/3000THRUST REDUCTION : 1500ftwould i be correct?


Paul McMahon

Ireland

747400.jpg

Share this post


Link to post

Hi Paul,You should be pretty tight reaching 3000ft by BUR at that weight but it should be possibe.The 1580 mentioned in your DVD is 80ft airfield elevation plus 1500ft so 1580 AGL. The real FMC takes a snapshop at 100kts of your height for its calculations.As you`ve probably seen in your video, Virgin Atlantic use 1500ft for THRUST REDUCTION and ACCEL HEIGHT.Try this real world procedure: you see that sharp right turn at bur towards wobun? if you start accelerating towards BUR the plane makes a very wide turn and you end up about 2 miles left of the required track to get to WOBUN.So what we tend to do is accelerate to flaps 5 bug+10kts keeping flaps 5 till we are around the corner,it should help with your climb rate.Also,not sure where you are getting your performance figures from,but just for you, here is the real world performance for EGLL 27R 15 deg C,no windFLAPS 20 ** TO/#### ** (104.33 %N1)CLIMB 427.7RUNWAY 425.9OBSTACLE 417.3STRUCTURAL 377.8ACT TOW 365200#### TEMP T=48 (99.36 %N1) V1 - 151 VR - 166 V2 - 175Remember our engines are slightly different from the PMDG version so there may be a small difference.Cheers Jon

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...