A question about the top of decent

[Guest stevepow]

I have been using radar contact for a while and have loved it. Today i was talking to a friend who flies on vatsim. I told him that i use radar contact for ATC as we continued our conversation i started asking him about descent speeds and he told me that as long as my fms was set up i would just have to lower the altitude to the next way point after the top of descent mark. I then realized that i have never been able to get that far into the flight plan. I explained to him that radar contact ATC has always started me down way before my top of decent and i thought this to be normal but he told me that it is not normal. is there something that i am doing wrong which is why ATC always starts my decent way before the top of decent mark? Thanks

[jd 57]

I have been using radar contact for a while and have loved it. Today i was talking to a friend who flies on vatsim. I told him that i use radar contact for ATC as we continued our conversation i started asking him about descent speeds and he told me that as long as my fms was set up i would just have to lower the altitude to the next way point after the top of descent mark. I then realized that i have never been able to get that far into the flight plan. I explained to him that radar contact ATC has always started me down way before my top of decent and i thought this to be normal but he told me that it is not normal. is there something that i am doing wrong which is why ATC always starts my decent way before the top of decent mark? Thanks

if you have the comms, you can respond to the initial descent clearance by replying with the PD option (pilot's discretion). then you can start down whenever you want.butbig butthe initial descent clearance is based on the distance to the arrival airport less 40 miles. it also calculates your crossing restriction, and determines when to start you down with an average descent rate.if you use the PD option, you better be prepared to meet the crossing restriction. there isn't a PD for that.jd

[ilarikousa 0]

In fact that IS normal. ATC instructions and clearances have priority over the FMS-calculated vertical profile. In the real-world ATC system, one can always *negotiate* about descent clearances, for example, delaying an ATC-issued descent or requesting a descent to match the calculated TOD. As a general rule, however, ATC has positive jurisdiction in their airspace, notwithstanding the PIC's authority, flight rules used, airspace class and other factors, of course. People who fly the networks often forget this because of the lack of continous ATC service -- the main reason I don't use them, except during fly-ins etc.

[dolin 0]

if you have the comms, you can respond to the initial descent clearance by replying with the PD option (pilot's discretion). then you can start down whenever you want.butbig butthe initial descent clearance is based on the distance to the arrival airport less 40 miles. it also calculates your crossing restriction, and determines when to start you down with an average descent rate.if you use the PD option, you better be prepared to meet the crossing restriction. there isn't a PD for that.jd

But where do we see there restrictions? I suppose they are not STAR restrictions, as RC doesn't handle such approaches. Further: what if you don't meet these restrictions? (I'm not talking about real-life where you can be charged for neglectancy, what does happen in the simulator?)Another question: in which menu is the PD descent button available? I mean, can you write the other options that are displayed in that menu, for better locating?thanks!

[ronzie 21]

The initial crossing restriction is hard wired into RC4 at 40 nm out as jd indicated. This is the typical altitude boundary where center airspace transitions to approach airspace (and position) negotiated by center and approach. These are published in some STARs as "expect to cross" or by altitude symbols with bars above, below, or none. These may be differentiated by aircraft type.RC5 will have a better handle on these characteristics.On flightaware.com looking at KMSP I monitored the altitude/position of jetliners and it pretty much followed the general conditions of RC4.If you want to deviate from the altitudes after the crossing restriction after contacting approach you must either in the preflight RC setup declare a NOTAMS arrival on the Controller page or in flight request an IAP to fully follow with your own navigation the completion of a STAR and IAP plate arrival.

[chrispeel 0]

GuilioThe "PD" descent option only appears if you have taken over the comms from Otto.It is Option 3 in the menu.You will also get an option to say"unable" if you can't make the 11,000 or 12,000 foot requirement when asked to do so..If you are doing a far side approach I find 12000 feet often to be too low and if doing a straight approach in it can be too high.When flying heavy jets that is.As has been mentioned in here before you need to be well slowed up if you are doing a straight in from 12000 feeet to a sea level airport.