Jump to content

Sign in to follow this  
Guest topcat

TO1 / TO2 with assumend temperature

Recommended Posts

Guest topcat

Hello forum readers,I have a technical question about the 747-400:Is it allowed to make a derated (TO1 or TO2) in combination with an assumed temperature take-off.I know Airbus does not allow a derated/assumed combination. I don't know if Boeing does.Any clues?

Share this post


Link to post

I am pretty sure some carriers do this. I am not sure where I was reading it, but someone from Singapore Airlines says that they use TO1 (fixed derate) in combination with an assumed temp. with their 747-400 series.So I imagine it is allowed.Hope this helpsRudy.


Rudy Fidao

Share this post


Link to post

As far as the NG goes you can derate and use an assumed temperature thrust limit. But you have to be very careful when doing so. See the below page for some discussion:http://www.b737.org.uk/assumedtemp.htmEspecially look at bullet 2 second paragraph:8<---A temporary form of de-rating known as a "T/O de-rate" is accessible through the FMC on TAKEOFF REF 2/2 or N1 LIMIT (NG's) but this is prohibited by some operators. The T/O de-rates (TO-1 & TO-2) can be 10 to 20%. It follows that an engine may be de-rated and also be using reduced thrust in which case you could be taking off at Full power -20% -25% = 60% of the full power of the engine - scary thought! Note that a T/O de-rate can overridden by firewalling the thrust levers; this action will give the thrust rating shown on the IDENT page.8<---The above will give you a clue as to wy some airlines don't allow derate and assumed temp thrust limit at the same time. 8-OCheers,


Mats Johansson
PMDG Flight Test Dept
Boeing777_Banner_BetaTeam.jpg

| Asus Z270-A | Intel i5-7600K @ 4.8 GHz OC/H2O | nVidia Geforce GTX 1070 8GB OC/O2|

Share this post


Link to post

I have personally witnessed from the jumpseat a combination of assumed temperature and derate. If I recall specifically, according to the analysis charts we took off using a TO2 with an assumed temp of 55. That's a lot of derate but we were on a 12,000 ft sea-level runway on optimal conditions and very light load. It doesn't get any better than this for a takeoff. It was a 777-200, but I'm pretty sure osme 747 carriers perform combination takeoffs as wellBest Regards,Victor Limahttp://www.precisionmanuals.com/images/forum/800driver.jpg


Cheers,
Victor M. Lima
 

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%
    $680.00 of $25,000.00 Donate Now
×
×
  • Create New...