Autopilot does not reach cruise on derated climb

[red259 31]

I noticed this my last few flights and I wonder if anyone knew how I could fix this. I'll do a derated takeoff with a climb 2. I takeoff fine and I engage my autopilot. Cruise is set to be FL220. The climb progresses as scheduled and the engines kick in for a stronger climb at the higher altitude. The problem is that when I get up to around FL220 my panels show that I am still in climb mode and it keeps pushing back my TOC on the map. This happens at waypoint after waypoint where I am supposed to be at cruise. I only started noticing this with derated takeoffs. I am not programming the required temp into the FMC as I don't have topcat. Could this lack of info be causing the issue?

 

Chris

[jasoncardeira 30]

Is the altitude set on the fmc the same as in the mcp ?

[red259 31]

Is the altitude set on the fmc the same as in the mcp ?

Yep.

[jasoncardeira 30]

it has nothing to to about topcat. So do you use TO-2 on takeoff and CLIMb-2 right ?  try to use CLIMB-1 OR CLIMB and see what happens

[DAL1850 51]

Make sure you're in VNAV and not another vertical speed mode. You won't automatically flip to CRZ thrust outside of VNAV.

[red259 31]

Make sure you're in VNAV and not another vertical speed mode. You won't automatically flip to CRZ thrust outside of VNAV.

vnav is active. I will check to see what happens with climb one. 

[DAL1850 51]

Altimeter set to 29.92?

[red259 31]

Altimeter set to 29.92?

Yes, set to standard after passing transition at fl180. 

[DAL1850 51]

I think in the panel or aircraft config there is an option for a derate washout altitude? Have you tried changing that? Standard, I think, is 12000' (though I think the NGX allows you to disable this or set it higher). It would be interesting to see if the derated thrust reverts to normal CLB at 12K and/or if it affects the behavior you describe.

[rsvit 16]

? Standard, I think, is 12000' (though I think the NGX allows you to disable this or set it higher). It would be interesting to see if the derated thrust reverts to normal CLB at 12K and/or if it affects the behavior you describe.

This altitude is set to 15000' on every 737 with no exception.

[DAL1850 51]

This altitude is set to 15000' on every 737 with no exception.

 

Thanks for clarifying.

 

If he's climbing to FL220, then his CLB-2 derate should automatically have washed out well before this point, no?

 

EDIT: Just tried this myself in the stock configured NGX 737-800...TO-2 with CLB-2...VNAV climb to FL220. Derate washed out at 15K, then CLB up to FL220 and then flipped over to CRZ thrust. Not sure what the OP is doing or maybe has configured differently.

[red259 31]

Just tried with climb one and had same exact result. It switches to normal climb at 15000 but when it gets to fl220 it refuses to switch to cruz thrust. There is an fmc message to reset mcp alt but its already set at 22000. Not sure why I am getting that message. FMC is setup for fl220 cruise.  

[DAL1850 51]

Just tried with climb one and had same exact result. It switches to normal climb at 15000 but when it gets to fl220 it refuses to switch to cruz thrust. There is an fmc message to reset mcp alt but its already set at 22000. Not sure why I am getting that message. FMC is setup for fl220 cruise.  

 

Can you post your flight plan? I wonder if your cruise altitude is too high...i.e. your T/D *precedes* your T/C. Reset MCP Altitude usually appears when the VNAV wants to descend but the MCP hasn't been set. It seems like by the time you arrive at your cruise altitude, your descent window has already passed - hence the FMC message.

[red259 31]

Can you post your flight plan? I wonder if your cruise altitude is too high...i.e. your T/D *precedes* your T/C. Reset MCP Altitude usually appears when the VNAV wants to descend but the MCP hasn't been set. It seems like by the time you arrive at your cruise altitude, your descent window has already passed - hence the FMC message.

In my flight plan there are about 4 waypoints at the cruise level of FL222. Maybe a 100NM between TOC and TOD. What is interesting is when I hit TOD all of a sudden that is when the cruise kicks in. I will try a slightly longer flight tomorrow and see if that makes a difference. 

[jasoncardeira 30]

Check if you got SP1c installed too