MD 80 auto thrust CLMP mode

MD 80 auto thrust CLMP mode

Postby AZJim320 » Thu Mar 08, 2018 3:56 pm

I recently bought the Fly the MaddogX for P3Dv4. I also have the Rotate MD 80 for XPlane 11. These are both great study level aircraft but unfortunately do not provide enough study level information to learn them properly in my opinion. I love flying them, but I have had a difficult time especially when it comes to the auto thrust and the CLMP mode. It took me several flights to learn that when I see CLMP it means I have to control the thrust levers. With this understanding I have been able to fly it successfully but not really understood just what is going on. Fortunately I flew yesterday with a guy who recently came to the Airbus from the MD-80 and spent about half his airline career flying it. It was a great opportunity to finally get some information on this system. I am sure many here have already figured this out, but I bet there are a few that could benefit from what I learned. So first when you see CLMP on the FMA the thrust levers are now controlled by YOU! First what he told me was on every takeoff at 60 knots the thrust goes into CLMP mode. The reason is in case of a rejected takeoff the auto thrust will not fight you pulling the thrust levers back, you have control. What you also need to understand is if you are not at takeoff thrust before 60 knots the thrust levers WILL NOT advance to takeoff unless YOU move them. This was one of the many things that went wrong with the Northwest accident in Detroit. They were still at 1.4 EPR at 60 knots.
Next he explained CLMP mode in flight. First he said that in the auto thrust control box there is really no electronics there are actually two hamsters. One is the speed hamster and one is the pitch hamster. They are trained how to operate in VNAV mode. They can control the aircraft in pitch and speed throughout the climb, cruise and at TOD will follow the the decent profile like experts. The problem comes when you want to deviate from this profile using (decent now), or IAS mode. When this happens they get confused and put you in CLMP mode. They are saying, “ your thrust levers” and you can then move them accordingly to do what you want the aircraft to do. I then asked him how he controlled the aircraft in the vertical mode when not in VNAV. He said he didn’t use decent now and never initiated a pitch change with IAS mode. He said it is not a smooth way to transition, it also confused the hamsters and puts you in CLMP mode. What he does is first use vertical speed 500fpm then as the aircraft starts to pitch goes to 1000 fpm. Once established he then will go to IAS mode. The transition is smooth, doesn’t confuse the hamsters and keeps you out of CLMP mode. I am looking forward to trying this next time I fly my MD 80. Hope this helps the people like myself that were trying to understand this system.

Jim
AZJim320
 
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Re: MD 80 auto thrust CLMP mode

Postby Dean33 » Fri Mar 09, 2018 12:30 pm

Thanks Jim.

Brilliant information.

I’ve spent the last 2 weeks on short MD80 hops around WUS. DAL 8082.

Just wondering which button feeds the hamsters?

Cheers
Dean33

UK P3DV4 Simmer
Pilotedge - I11, CAT11, A-Z (ZLA), A-Z (WUS)

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