Need help with A/P going TOGA during climb and selecting flaps 10

[chapstick 2,757]

I need some help figuring out what I'm doing wrong on take off using the 747 when its set to reduced to CLB thrust at flap 5 selection. When I select flaps 10 after taking off, it kicks off LNAV/VNAV and goes TOGA. What am I doing wrong? See the pics with descriptions below.

Thanks.

Alex Pugh

[Captain Kevin 586]

Just a guess, mind you, but your first waypoint appears to read "vectors", which isn't an actual waypoint, but rather, air traffic control would vector you to your first waypoint. You wouldn't be able to use LNAV in that case, as heading select would be more appropriate. Try replacing vectors with your first waypoint and see what happens.

[chapstick 2,757]

3 minutes ago, Captain Kevin said:

Just a guess, mind you, but your first waypoint appears to read "vectors", which isn't an actual waypoint, but rather, air traffic control would vector you to your first waypoint. You wouldn't be able to use LNAV in that case, as heading select would be more appropriate. Try replacing vectors with your first waypoint and see what happens.

Yeah, I knew should've used a different SID for the test but it actually happens on SIDS that start with way points and not vectors.

[Mike777 163]

3 hours ago, Chapstick said:

I need some help figuring out what I'm doing wrong on take off using the 747 when its set to reduced to CLB thrust at flap 5 selection. When I select flaps 10 after taking off, it kicks off LNAV/VNAV and goes TOGA. What am I doing wrong? See the pics with descriptions below.

Hi Alex,

Looking at your  pictures, I think there is either a bug or you are somehow pressing TOGA when you go to flaps 10.  The FCOM, page 4.20.9 = pdf page 667 describes the behavior you are seeing as happening "if a TO/GA switch is pressed before the reference thrust limit changes to climb."  You haven't even yet selected the flap setting (5) that should initiate the thrust reduction change. 

I don't think the waypoint being "vectors" is a problem -- not sure, but based on my experience in descents, in LNAV the plane should just keep going on the same heading.  Also, the first waypoint is a conditional one in line with the runway, 600ft.  At any rate, there is still adequate information for VNAV to continue functioning, namely, an altitude.

How are you controlling flaps settings?

What happens if you choose a Thrust Reduction Altitude instead of a flap setting using the same takeoff scenario/runway/SID (I think this would indicate a bug if Altitude works OK)?

I can't experiment with this issue at the moment as my FSX computer is on the fritz and in the shop.

 

Mike

 

[chapstick 2,757]

6 hours ago, Mike777 said:

Hi Alex,

Looking at your  pictures, I think there is either a bug or you are somehow pressing TOGA when you go to flaps 10.  The FCOM, page 4.20.9 = pdf page 667 describes the behavior you are seeing as happening "if a TO/GA switch is pressed before the reference thrust limit changes to climb."  You haven't even yet selected the flap setting (5) that should initiate the thrust reduction change. 

I don't think the waypoint being "vectors" is a problem -- not sure, but based on my experience in descents, in LNAV the plane should just keep going on the same heading.  Also, the first waypoint is a conditional one in line with the runway, 600ft.  At any rate, there is still adequate information for VNAV to continue functioning, namely, an altitude.

How are you controlling flaps settings?

What happens if you choose a Thrust Reduction Altitude instead of a flap setting using the same takeoff scenario/runway/SID (I think this would indicate a bug if Altitude works OK)?

I can't experiment with this issue at the moment as my FSX computer is on the fritz and in the shop.

 

Mike

 

Mike, you nailed it! For some reason I had the 747's hot key combo for TO/GA assigned in FSUIPC to the same button I assigned in P3D to flaps up. Thanks!

[Mike777 163]

4 hours ago, Chapstick said:

Mike, you nailed it! For some reason I had the 747's hot key combo for TO/GA assigned in FSUIPC to the same button I assigned in P3D to flaps up. Thanks!

Glad it's fixed!

I never noticed that thrust reduction could be controlled by flaps selection -- from 777 FCOM, that appears to be the case for the T7 as well!  So thanks for drawing that option to my attention.

BTW, there is a known issue in FSX if you should happen to use FSUIPC to control flaps directly.  The flaps look like they are up but the sim detects them as still down, and the aircraft won't climb or accelerate well.  Don't know if this happens in P3D.  I do use FSUIPC to control flaps, but only to send the default button commands (F6 & F7) using buttons on my joystick, with no problem.

Mike

[Captain_Al 66]

Typically, most airlines use either a Distant Community or Noise Abatement type profile, commonly referred to ICAO B or ICAO A. 

The distant community is a non-noise profile of 1000 feet acceleration height and a Flaps 5 Thrust reduction and the noise abatement is a 3000 feet acceleration height and a 1500 feet thrust reduction on the TAKEOFF REFERENCE page.

[Mike777 163]

3 hours ago, Captain_Al said:

Typically, most airlines use either a Distant Community or Noise Abatement type profile, commonly referred to ICAO B or ICAO A. 

The distant community is a non-noise profile of 1000 feet acceleration height and a Flaps 5 Thrust reduction and the noise abatement is a 3000 feet acceleration height and a 1500 feet thrust reduction on the TAKEOFF REFERENCE page.

Interesting!  I suppose in  the 777, where flaps 5 is a common takeoff setting, the non-noise profile would use flaps 1.

Mike

[Captain_Al 66]

Not being a 777 guy, I think that is correct. In the 787, a valid entry in the thrust reduction field is 1 or 5. If you are taking off with Flaps 5, then it will give you an Invalid Entry if you try to put in 5 on the TAKEOFF REFERENCE page. If you are taking off with Flaps 15, then 5 would be a valid entry, if you are taking off with Flaps 5, then 1 would be a valid entry. I would think the 777 would be similar.

Now whether most airlines use that or not, I am not sure. It may be different in the 777. In the 787, we really use an altitude for thrust reduction more than a flap setting, but in the 747, it is somewhat common to use a Flap setting if it is a non-noise abatement takeoff. Just depends on what the airline SOP is.