Last flight I was derated and pushed throttles up to 55%, stabilized and hit TO/GA. After t/o I saw the speed increasing way too quickly. The amount of pitch needed to maintain V2+20 would have been way too much. I attempted to override the mode the plane was in with with some type of SPD intervene on the MCP and couldn't figure it out. Need to work more on it for sure.

I have sometimes found my hardware throttles will re-capture in Hold mode (even though I have moved into the null zone), usually resulting in the N1 value busting through the expected derate. Physical Throttles override auto thrust [never] option in the FMC PMDG options can mitigate this, but I have seen it not do that once or twice.

You still haven't confirmed if you're using derated take off or not.

 

Try TO2 and 60 degrees C to start.

 

That fixed it,  even with the 777-200 full pax and cargo (but not fuel) I guess those engines are just too powerful

That fixed it,  even with the 777-200 full pax and cargo (but not fuel) I guess those engines are just too powerful

Glad that helped. Yes those engines are big and you have two of them! Just remember that it was designed to fly with just one engine. B)

 

 

I've been flying the PMDG 737 for a long time, and basically I am using the same procedure to setup the 777 for takeoff, but with different parameters obviously. But this plane is cruising like mad, by the second waypoint in the SID it is almost 300 knots even though the speeds are limited in the FMC. After a few seconds it slows itself down and recovers.

 

Are you by any chance having these "rocket" take-offs after loading a saved flight with FMC programmed and all set to go??

 

I saved a flight all set up to go for pushback. This included Takeoff settings (derated thrust settings and Vspeeds), and for the life of me I could not get any control of the speed at takeoff, other than by pitching up very high (6000ft/min climbs). I soon realised she was taking off at full GA thrust, ignoring my TO derates, MCP speed settings, and climb thrust settings (CLB2).

 

Then I saw that "Thrust Ref" was not enunciating on the PFD after selecting TO-GA, and the heading and vertical mode fields on the top line of the PFD both had green "TO" enunciated, instead of the "TO/GA" which are normally there for a derated takeoff (if you see "TO" in these fields you are in for a Cape Kennedy experience). Clearly my takeoff settings were being ignored.

 

So I re-loaded the saved flight and did this;

 

Turn off both "AT/ARM" switches.

Turn off both Flight directors

Change the Takeoff settings on the FMC. I just re-entered the derate temp. You should get the message "Vspeeds deleted"

Accept new Vspeeds

Turn "AT/ARM" switches back on

Turn both Flight directors back on.

 

This time it worked absolutely perfectly, with a nice slow, steady climb-out, and speeds properly managed.

 

Rule seems to be that if you load a saved flight with FMC fully programed, you must re-initiate take-off settings by disarming Autothrottle and Flight Directors, re-affirm TO settings and Vspeeds, and then rearm Autothottle and Flight Directors.

 

Obviously one should not have these problems loading from a cold-and-dark state, or from a saved flight where no FMC programming has been saved.

 

Regards

Rob

No saved flight

 

 

the heading and vertical mode fields on the top line of the PFD both had green "TO" enunciated, instead of the "TO/GA"

 

Well that in its own right indicates a problem as it is not possible to get TO as an FMA mode at any time.

 

Best regards,

Robin.