Note sure if it’s a issue with the aircraft or my lack of understanding but every time I take off in the 737 Max 8, I do the following. Set altitude, turn on VNAV and LNAV, fd, enable auto thottle, set V/S with a climb rate of 2000 fps and I set the speed manually to about 220 kts. When I lift off and start climbing the speed setting reverts to the FMC setting which is always faster than 250 so I get an overspeed below 10k ft. How do I stop this? I couldn’t find a way in the FMC to set the speed to 220 on climb.
The small round button just to the right of the speed dial on the MCP is SPEED INTERVENTION. So you set your manual speed on the dial and hit that button or the aircraft will go over 250kts below 10k ft. If you are in career mode. I find I have to set about 235kts on the dial to stop it going above 250kts then above 10000ft I hit the speed intervention buttion again which returns it to FMC controlled speed.
I do this but the spd I enter (220) is blanked as soon as I take of and the plane sets it’s own speed of around 290. I have to remember to try and set spd intv again but normally it’s too late and we are already over speeding. This happens every time I take off.
Hello, a couple of things Boeing (and it’s possible that the Max 8 model is in some ways defective):
- It could be that the FMC is not completely set-up in some respect, or the model is defective.
- VNAV and V/S modes are mutually exclusive, use either one or the other at any given time.
- You could try Flight Level Change along with your airspeed setting, see if that works for you.
I’m usually in VNAV when I do the SPEED INTV. It does work. Make sure your FMC is set up properly, the MCP has both FD’s on, Auto throttle armed/ON, and VNAV armed (before takeoff) & engaged (after takeoff). After retracting the landing gear and then flaps the speed intervention is the first thing I generally do in career mode to stop the Max shooting over 250kts.
The autopilot is pretty confusing in the 737 MAX 8 to me and it keeps overriding what I put in also (probably a skill issue but oh well). I finally just started hand flying until past 10k – I really enjoy the extra hand-on-stick time also, YMMV of course.
update: that I also found (a while back now) that you can use LVL CHG mode and control the speed manually on the MCP, just dial in 210 knots before you take off – you can preselect LVL CHG. Then it will automatically engage when you enable the autopilot. Combine this with a derated takeoff for a smoother climb out experience (assuming you have the runway available of course). You’ll want to increase that speed to 240 knots at some point–just stay well above your stall speed before you go full flaps up. Once I get above 10k I hit VNAV.
However… now I’m finding in VNAV when you get up around 35-40k and are still climbing the FMS will let you get way overspeed (into the barberpole overspeed) because it kind of “stuck’“ in N1 mode. At that point I have to use V/S.
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