Radar Contact and the PMDG 777 Question

[macpilot 22]

I've just started to use the PMDG 777 with Radar Contact. When RC tells you to start your descent earlier than the FMC in the 777 is programmed, how do you handle that situation?

 

Thanks to all who reply.

 

Bill

[Ray Proudfoot 8,932]

Bill,

 

This is a common question (and often, complaint) from new RC users. You will need to initiate the descent to keep the RC controller happy. But providing it's 200fpm or greater he'll be fine with that. I usually keep to that descent rate on a 737-800 until the descent proper is required (based on your CDU ToD point)

[Cristiano Mueller 9]

Hi guys;

 

I'm with Ray. Moreover, taking into account that in real life is the air control who has the responsibility to guide you through the airspace, no matter what FMC tells to you.

 

So, if RC tells me "down!!", I obey.

[James Bennett 52]

Hit descend now in the FMC that way you won't confuse it.

[macpilot 22]

Thanks Guys,

 

Another question. As I start my approach, RC wants to vector me to the runway. I want to perform an ILS approach. RC won't let me select any selections but 1 and 7. So none of the other selections are available. With any other aircraft I haven't got this problem. So it must be something within the PMDG 777 that is preventing me from doing this. Am I correct or am I missing something.

 

Thanks Bill

[Ray Proudfoot 8,932]

Bill,

 

RC doesn't know (or care) what aircraft you fly other than what option you choose on the Aircraft options page.

 

You cannot override your filed plan until you contact Approach - 40 miles out. At that point you will see additional options including 4 - Request IAP.

 

Choosing that option will gain you access to a further menu and option 2 - ILS will give you a list of runways to choose from. Make your choice and RC will leave you to fly the approach until approx. 7 miles out when you'll be instructed to contact Tower.

 

One tip after contacting Approach and before requesting the IAP option. RC will always give you a heading to fly and altitude to descend to. Ack the instruction and initiate the descent. Then request the IAP. The reason for doing it in this order is you cannot cancel the heading and altitude change instruction.

Hit descend now in the FMC that way you won't confuse it.

 

That may descend you faster than you want. Use Vert Speed and dial in 200fpm. That way you can stay higher (and faster) for longer.

[macpilot 22]

Thanks again to everyone who replied. On my next flight I'll try your suggestions.

 

 

Ray,

 

Should those options 2, 4, and etc. be available during the flight. Example leave the frequency to check the weather, Request different altitude? They didn't seem to work. I understand RC doesn't care what aircraft your flying. But I know they have worked before.

 

Thanks Bill

 

 

[ronzie 21]

Once you are the last stages of center descent and near approach range extra options are restricted.

 

In the B737 for guidance I place a range ring around the destination airport at 40 nm out. This is a guide to meet the crossing restriction assigned by RC. One at 30 nm out can guide you to the lower speed restriction of the airport traffic range.

 

In the B737 FMC to get a range ring bring up the FIX page. Enter the ICAO code for destination as the FIX identification. On the bearing distance entry choose /40 and EXE it. Use /30 for the 30 nm range ring.

 

If you want your FMC to estimate your TOD more closely choose an waypoint on your LEGS page about 40 nm out if available and give it a hard altitude of 12000 or FL120 although your crossing restriction might be 11000 FL110 instead. It depends on the estimated runway and your arrival direction.

 

The FMC bases its TOD on a constant descent to the airport elevation. RC calculates its TOD based on the altitude difference between your current cruise and that of the crossing restriction at 40 nm out. RC uses this estimate;

 

http://en.wikipedia.org/wiki/Rule_of_three_%28aeronautics%29

 

but some airliner pilots do the math as a cross-check of the FMC.

 

My experience is that in approach after the crossing restriction I can avoid a few of the stepped descents by carefully maintaining aircraft speed and V/S watching the descent arcs to the airport.