Sekkha

How to comply with RC crossing restriction

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Hi all,

just a question regarding the use of the FMC.

RadarContact normally gives a crossing restriction like "be leveled in 30 miles or less". I was wondering how to comply with that using the FMC. Is it possible to create a new Fix on the route 30 miles ahead which is not related to any waypoint ? Or any other accurate method  ? (For the moment I am using the green decent range circle, but obvioulsy that isnt accurate enough)

thanks in advance for your help

 

 

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Hi,

Yes you can. It is called along-track waypoints. Just enter XXXXX/30 where XXXXX is the waypoint from which you count the 30nm. 

Then enter a altitude restriction at the along-track waypoint created.
The FCOM page 11.31.17 explains it but it's worth reading from 11.31.11 as you will be taught all the different formats to enter waypoints in the leg page.

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1 hour ago, Suniram said:

be leveled in 30 miles or less

That does not sound like proper ATC phrasology, as defined in 7110.65. First, I'm not sure what that restriction means, does it mean climb to and maintain xxx ft by 30 nm from  xxxxx fix? That I would understand in certain situations.  Romain is correct; however, you'd be better off flying the airplane and not fiddling with inserting pseudo waypoints you really don't need.  If you have a VOR along your course use the DME for your distances.

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Thanks for your replies ,

 I know about those along-track waypoints,  however the problem is that those 30nm are not to be measured from any waypoint but  from the current aircraft position - whereever that is at that moment.

Anytime the controller will tell you to decent to 12000ft or 11000ft and to be leveled there in 30miles or less...So you cannot refer to a waypoint. What would be needed is a new waypoint along the route just 30nm ahead of current aircraft position......I couldnt find anything about the possibility to create those..

 

 

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Radar Contact had many nice features, especially considering when it was released. But one thing I truly despised was that "I need you down in 30 miles or less" crossing restriction. It would always kick me out of my nice easy VNAV profile and put me into a screaming nosedive. I never did figure out how to get the FMC to comply with that restriction. I simply made a mental note of where on the ND those 30 miles were and made sure my green banana always stayed ahead of that point. Not very scientific, I know.

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Yeah, I hate that as well. I just manually descend with LVL CHG. Vnav don't work so well with RC. We need a new ATC software badly. I've tried pretty much everything that's out there right now, but I always end up back to RC.

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Walter, I completely agree ....somewhat annoying this "I need you..."

So maybe the best way would be to check the distance to the next waypoint and then calculate the difference to 30NM and insert one of those along-track-waypoints refering to the next WP...

or just respond with "unable" :cool:

 

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4 minutes ago, DLWbluues said:

Yeah, I hate that as well. I just manually descend with LVL CHG. Vnav don't work so well with RC. We need a new ATC software badly. I've tried pretty much everything that's out there right now, but I always end up back to RC.

Pro-ATC/X, as of the update that was done last week, is now quite usable. There's still a lot of silliness that needs to be changed, such as hoaky phraseology and terrible taxi instructions (to name just a few) things), but at least now it seems to be quite reliable for a flight from start to finish.

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back when i used radar contact i noticed that the crossing restriction on descent was always exactly 40nm from the destination airport at 11000 or 12000 feet, so i would create a 40nm fix from the airport.

i think the format was to enter the icao code in the fix page, and then enter /40 for the fix entry which creates the 40nm circle. you could then take that fix and line select it into your flight plan, add the 11,000 restriction, and it works every time.

do exercise caution as sometimes that point would be in a mountain or something also so keep an eye on the terrain map :)

cheers,-andy crosby

 

 

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3 minutes ago, Suniram said:

or just respond with "unable"

Sure, but then he yells at you. and I already get yelled at enough in my daily life. Don't like feeling abused when it comes to my hobby. :biggrin:

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2 minutes ago, spesimen said:

i would create a 40nm fix from the airport.

Nice idea, Andy!

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8 hours ago, spesimen said:

back when i used radar contact i noticed that the crossing restriction on descent was always exactly 40nm from the destination airport at 11000 or 12000 feet, so i would create a 40nm fix from the airport.

i think the format was to enter the icao code in the fix page, and then enter /40 for the fix entry which creates the 40nm circle. you could then take that fix and line select it into your flight plan, add the 11,000 restriction, and it works every time.

do exercise caution as sometimes that point would be in a mountain or something also so keep an eye on the terrain map :)

cheers,-andy crosby

 

 

thanks , that sounds good, will try it...

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10 hours ago, Suniram said:

Thanks for your replies ,

 I know about those along-track waypoints,  however the problem is that those 30nm are not to be measured from any waypoint but  from the current aircraft position - whereever that is at that moment.

Anytime the controller will tell you to decent to 12000ft or 11000ft and to be leveled there in 30miles or less...So you cannot refer to a waypoint. What would be needed is a new waypoint along the route just 30nm ahead of current aircraft position......I couldnt find anything about the possibility to create those..

 

 

If ATC want you to be at a specific altitude by a certian point they would say "Descend to FL120 by Alpha Charlie." To say "be level at FL120 in 30 miles" is not correct phraseology. How would you measure that? If you are not navigating by a VOR/DME it's impossible. Discount GPS as that is not the assumed navigation aid. RC4 is very outdated in phraseology and methodology now.

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