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737 RTO and VS problems

PostPosted: Sat Jun 02, 2012 7:13 am
by Demious
I'm trying to fly the default Boeing 737-800 and most things work fine, only the RTO and VS are giving me problems.

First the RTO. I understand that RTO will automaticly brake, when the throttle is pulled back during takeoff, but what happens for me, is that every time I try to take off, the auto brakes get applied around the speed of 80-85kias, while the throttle is still being increased by the autothrottle.
This way I never get in the air with the use of RTO. Can anyone tell me what can go wrong here and how I can fix it?

A second thing is that the virtical speed of the autopilot often only goes up to around 500ft/min, while in the VS-screen is a setting visible of 1800ft/min and I have to move the VS setting back and forth to have the aircraft go to the indicated setting. What can I do to fix this?

Re: 737 RTO and VS problems

PostPosted: Sat Jun 02, 2012 9:25 am
by Fishbed7701
It seems like you are activating the autobrake on takeoff. Not something you want to do. Make sure you only activate it just before landing. With the vertical speed, I'm not sure I can help you. What aircraft are you flying and do you have the ALT hold set or the master AP set?

Re: 737 RTO and VS problems

PostPosted: Sat Jun 02, 2012 9:43 am
by DaveSims
If you are using the autothrottle during takeoff, which I don't usually recommend, you need to hold the brakes until the engines get spooled up some.  If the autothrottle is still advancing the throttles at 80 kts, you are way behind and using too much runway.  What is probably happening is the autothrottle is adjusting a little and may be decreasing throttle slightly, triggering the autobrake. 

Also, are you using the autothrottle with the TO/GA button, or setting a certain speed?

Re: 737 RTO and VS problems

PostPosted: Sat Jun 02, 2012 10:40 am
by Demious
I'm practicing takeoff with autothrottle indeed, I've tried it with TO/GA, but that doesnt do anything and when I tried it with speed hold, it seems to work fine, as long as the auto brakes are in the OFF position.
I've got A/T armed and I rev up the engines to about 60% N1, as my checklist tells me to, then release the brakes and activate speed hold, to have A/T perform the rest of the acceleration to the programmed speed: V2+15kias

Both checklists from FSX and the extended one I downloaded, tell me to turn autobrake to RTO, so that's what I'm doing...

Another thing, I want to start with the engines turned off, the checklist tells me that I need to turn the master starter switch to OFF, for chutdown procedure, but I cant find anything called Master Starter Switch and no matter what I turn off, the engines keep running.
Can anyone tell me where those are located? For now on the 737-800, but also in general, been trying to find them on other models too, but I can turn off everything, except for the engines...

Re: 737 RTO and VS problems

PostPosted: Sat Jun 02, 2012 7:56 pm
by dave3cu
Can anyone tell me where those are located?


They're located below the throttle levers. In the vc the tool tip will id them as 'engine fuel control switch'. In the 2d ECU pop-up the tool tip will id them as 'master starter switch'.

Re: 737 RTO and VS problems

PostPosted: Sat Jun 02, 2012 9:05 pm
by Rocket_Bird
I used to get this autobrake problem.  If you have a joystick with throttle or a throttle quadrant, and you are using the autothrottle, try to press your throttles forward or move them all the way up as the engines are automatically advanced to take-off power.  If your controls are down too far, the sim might register that as you pulling your levers back and the brakes will apply. 

Re: 737 RTO and VS problems

PostPosted: Sun Jun 03, 2012 2:22 am
by Demious
Ah the problem is in the hardware and not in what the software shows on the screen, I'll have a go at it.

Found the switches. Those are levers, while I've been looking for real switches, that explains a lot. And that they change names for it doesnt make it easier, but ok...

Thanks a lot guys :)