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Hello Folks, I am experiencing trouble with a SID. I am getting 'DISCO INSRTD AFTER (500)' I have checked this using Terry Yingling's guide for this type of error, but still can't get it sorted. Here is the SID:SID MARUB3 RNW 34R KEEP HDG UNTIL 500 HDG 120 INTERCEPT RADIAL 075 FROM NAVAID SY FIX MARUBHeading for Rnw 34R is 335.I have got around this by creating and inserting a FIX after 500 which is placed within the arc of a turn to 120 degrees to ensure that you intercept the 075 radial. However, I cannot logically understand why the original code will not work. It almost seems like you need to force the plane through 360 degrees to make it work.I guess I am missing something real simple here. Any assistance would be appreciated.RegardsJock McIntyreYMML

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Hi Jock.I think the reason for the disco is that the FMC calculates that you will reach the 500 restriction before you reach the 075 radial. If you , just for a try, insert 2000 as the altitude restriction, then you will get no disco.If you close the disco you'll get a turn direct to MARUB, not quite precise, but just after you kicked in the AP though.My solution here is would be to insert a fix on the 075 radial from SY, lets say 5NM out. Then you'll get a smooth turn after 500.Try this one: (I assume this is YSSY)FIXESFIX D75 COLOCATED SY 75 5ENDFIXESRNWSRNW 34RENDRNWSSIDSSID MARUB3 RNW 34R TRK 335 UNTIL 500 SPEED 180 FIX D75 SPEED 180 NAVAID MARUBENDSIDS

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Guest stang

Howdy Jock>SID MARUB3 RNW 34R KEEP HDG UNTIL 500 HDG 120 INTERCEPT>RADIAL 075 FROM NAVAID SY FIX MARUBMight be an intercept problem but it's kind of difficult to tell intercept angles from the SID above. I could not find a MARUB3 SID in the DAFIF data. What airport are you working on? RegardsTerry

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Guest stang

>>SID MARUB3 RNW 34R KEEP HDG UNTIL 500 HDG 120 INTERCEPT RADIAL 075 FROM NAVAID SY FIX MARUBHi there JockOK. I think I have your problem figured out. In short, the 500 foot altitude is reached before going north of the SY R075 so the intercept can not be made as written. To see this activate your SID and then go to the FIX page and plug in SY for the FIX and 075/2 for the RAD/DIS. Then look at your display in PLAN mode. The 075 radial will be shown as well as your route. You can see the computed (500) is south of the radial 075. Therefore a heading of 120 will not intercept the radial. You could change the intercept heading to maybe 30 degrees for a 45 degree intercept angle and that will fix the DISCO but the route then is not like the SID plate. This may be one that you might want to hand fly until you intercept the 075 and change the written SID accordingly.Good luckTerry

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Per & Terry, Well you have both come up with the same reason while I have been sleeping and working (more of the later, unfortunately).When I look at the YSSY airport chart and the positioning of the SY VOR in relation to 34R, it is very conceivable that the kite could be above 500 before passing the VOR. That has fixed the logic around it all for me.So, I now have 3 'fixes' including my own. I often ride this SID (as a passenger) and I will work out what appears more realistic.Thank you both for your response. It is most appreciated.RegardsJock McIntyreYMML

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