77L Derate Washout During Early Climb

[ESzczesniak 128]

I was hoping someone could help me figure this out.  I'm flying the 77L for "extended" pattern work.  I'm using a freighter model empty with light fuel, so rather light.  As a result, I'm using TO2/CLB2 with assumed temps of ~60 (using TOPCAT, real world weather at KCLT). 

During my climb to 1,500 I'm loosing the CLB2 and the thrust limit goes the CLB, then GA.  With such a light aircraft, I'm almost always busting my planned initial altitude of 5,000'.  This seems to happen with AP on or off and using either VNAV or FLCH for the FD vertical mode.  Thrust annunciations on the PFD are THR and it does show on the EICAS TO2 to CLB2 before advancing to CLB and GA.  Typically CLB happens about 2,000 AFE and GA 3,000-3,500 AFE.

I've checked all my joystick buttons.  I'm using a Saitek yoke and dual throttle quadrants.  Nothing is assigned in to any of the joysticks except throttle 1/2.  The remainder of the axes and buttons are assigned in FSUIPC.  I do have one button set to SHFT+CTRL+G to initiate TO/GA thrust, but I don't see any evidence that this is a dirty signal sending unplanned TO/GA command.

I have the FMC setup for basically an NADP1 with acceleration height and thrust reduction/retract height of 1,500 for both.  Derate washout is set to 12,000' on my bird.  I have the aircraft set to always ignore my throttle axes with AT on.

Perhaps this is a setup issue, but any thoughts or suggestions?  Any quirks about the aircraft that I don't know about that could contribute to this?  Thanks for any thoughts and help.

 

[downscc 1,327]

That light you pretty much have to intervene to level at 5000.  I've no idea why thrust limit goes to GA unless for some reason the flight segment is advancing to the approach.  I do my pattern work at 3000 and she will overshoot but it helps if you keep the speed down to maybe 220 just above the clean min maneuver speed.  That might make things easier for you.  Why not put a little more fuel in her too?

[ESzczesniak 128]

1 hour ago, downscc said:

...I've no idea why thrust limit goes to GA unless for some reason the flight segment is advancing to the approach...

That could be a great point.  I'm programming the FMC just with the departure runway (to get the auto Vspeeds) and ILS approach (for autotune).  Very early on it may be switching.  I'll have to pay attention and/or add another departure waypoint a bit further from the runway to see. 

[downscc 1,327]

54 minutes ago, ESzczesniak said:

That could be a great point.  I'm programming the FMC just with the departure runway (to get the auto Vspeeds) and ILS approach (for autotune).  Very early on it may be switching.  I'll have to pay attention and/or add another departure waypoint a bit further from the runway to see. 

I always stick an enroute waypoint in there, such as a VOR somewhere around, even if I'm not going to fly to it.  The early PMDG FMS coding would hiccup without an enroute fix and now its a habit.