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PowerDrag

Aircraft taking shortcuts?

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Hi I am not an expert in civilian airliners. Always been a military flier, but I purchased the MD-11 as I love it in real life.

 

My issue is the aircraft is not flying waypoint to waypoint, like I would expect but rather taking some shortcuts.

I have attached a picture of the ND from the approach and you can see that it's not flying over the waypoints one after another.

Is there a way I can stop this behaviour? It's resulting in the A/C being well above the glide slope and causing a violent pitching down on rollout.

 

 

 

Colin W

 

Edit, No permission to upload the screenshot :/

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I've noticed the Aerosoft Airbus do that aswell. I'll say the aircraft is trying to smooth out the turn and avoid doing a sharp turn. Maybe those who know more will let us know if I'm right or not.

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The aircraft has to lead the turn in order to roll out on the new course without overshooting it. The aircraft can not stop in mid air and then pivot. It is normal behavior for the FMC to take turning radius into account and display the anticipated track on the ND.

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My issue is the aircraft is not flying waypoint to waypoint, like I would expect but rather taking some shortcuts.

 

 

At a distance range of 5 miles you are going see a lot of weird things. The attached image shows the route even bypassing the KEC VOR which is part of the route for KOAK-RJBB. Normally I would use a range of 80 miles because the MD-11 is just starting the descent into RJBB from FL380 but I decreased it to 5 miles to show you this image. I would not use a distance of 5 until I was within 10 miles of the runway

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It's called a "smart turn" to make the turn more comfortable to passengers and, as said above, to establish the aircraft on the new track smoothly. If there is a requirement to Fly Over not Fly By a way point then you must tell the fmc to overfly the way point, otherwise it will just smart turn them by default.

 

In your first screenshot you asked the fmc to fly quite a tight maneuver, if it didn't smart turn there's a high possibility it won't make the track for the next way point and could miss it entirely. 

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Thanks for the help! It wouldn't bother me except that this is actually a real life STAR and it's not meeting the altitude restrictions because of the lead turn. Hopefully that FMC trick will help.

I Might just have to hand fly it ^_^

Thanks again for the help.

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Have you tried flying the approach at a slower speed?  Then the plane may be able to make the final turn.

 

Clark

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Thanks for the help! It wouldn't bother me except that this is actually a real life STAR and it's not meeting the altitude restrictions because of the lead turn. Hopefully that FMC trick will help.

I Might just have to hand fly it ^_^

Thanks again for the help.

 

 

Just manage your profile manually and you'll hit your altitude requirements everytime, i'm always wary of any FMC managing a descent for me.

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I usually take manual control of the vertical profile, and opt to use IDLE DES instead (forgive me - I forget the precise MD-11 terminology right now). Pulling the ALT knob will enter this mode.

 

As written above, chances are you are flying too fast, and unable to make the turn. It requires judgement.

 

Best regards,

Robin.

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