How to delay the descent?

[ghiom 2]

solved

 

From the manual:

"Controllers, not FMCs, determine when initial descents are started but those using FMCs will 

like this! While at cruise altitude and when you get your 1st descent clearance you will notice 

the menu item “3-PD”. Use this feature to request a “Pilot‟s Discretion Descent”. The RC 

controller will approve or deny this request depending on varying circumstances."

[Ray Proudfoot 8,921]

Just to add my own experience to this point. During testing I managed to request a PD 10 times before finally being granted one.

 

In the real world you wouldn't dare question the controller but in the RC world you can. OTOH, if you wish to obey him but stay as high for as long as possible (based on your CDU ToD) a descent rate of 200fpm is enough to satisfy the controller.

[ronzie 21]

FYI:

 

Your FMC TOD is calculated to your first hard altitude in your FMC LEGS or to the airport surface using the "three to one" decent rule of thumb. RC bases its first descent instruction position based on your current altitude difference to the anticipated 11,000 foot/FL110 or 12,000 foot/FL120 altitude using the same rule of thumb. The crossing restriction occurs at about 40 nm out from the airport and which altitude depends on the anticipated runway and arrival direction.

 

To assist in meeting the 40 nm out crossing restriction on the FMC I place a 40 nm range ring around the airport. (At the same time I notice in cockpit videos some pilots add a 30 nm range ring to display the usual local airport traffic area of reduced speed.)

 

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

 

On a Smiths type FMC as used in many Boeings go to the FIX page. Enter the ICAO identification for the arrival airport. In the distance/bearing field just enter /40 and EXE. (I do this preflight.) You'll now have for display only on your EHSI nav display the indicated range ring as a dotted line around the airport. This allows me to use descent arcs and V/S (getting off of VNAV) to meet the altitude restriction.

 

My experience is that with proper speed and V/S control RC may issue a further descent before you get to the next commanded altitude during the approach phase offering almost a constant descent until the traffic pattern entry.

[Driver170 42]

I use the 737 NGX place a 40nm ring in the fix page with ICAO code. And in the legs page i create a waypoint so its on the 40nm ring. Then enter the altitude and speed rest.

[ghiom 2]

As a matter of fact, I did not get the option 3-PD after the request for descent. I am on 4.3.3845.

Am I missing something?

Thanks

Ghiom

[ghiom 2]

OK!

I need to have Comm...

Sorry if I missed that.

Ghiom

 

Edit

I tried with Comm with me but still did not get the option in the menu...

[Ray Proudfoot 8,921]

 

 

I tried with Comm with me but still did not get the option in the menu...

 

Your cruise altitude may be a factor. What was it?

[ghiom 2]

I made tow flights yesterday.1st one I was cruising at FL390, the 2nd at FL360.

I also read somewhere after these flights that you needed to have the Pilot's reply back unchecked to get the PD option. I haven't tried that yet. That could be the ultimate reason.

I'll report back in any case.

Thanks

Ghiom

 

ps: too bad this product is no longer developed. It's so great and has so much potential...

 

.

[Driver170 42]

ps: too bad this product is no longer developed. It's so great and has so much potential...

 

Yep

[Ray Proudfoot 8,921]

 

 

I made tow flights yesterday.1st one I was cruising at FL390, the 2nd at FL360.

I also read somewhere after these flights that you needed to have the Pilot's reply back unchecked to get the PD option. I haven't tried that yet. That could be the ultimate reason.

 

For those levels you would definitely have the 3-PD option but only if you have comms. if you've assigned Otto to comms he'll ack it immediately and you'll be expected to comply and start your descent.

 

As I said earlier, what you can do there is initiate a 200fpm descent and that will keep RC happy up to the point where the descent proper needs to start.

[ghiom 2]

OK, thanks for the tip, but I'd like the VNAV descent to start at ToD. The iFly 737 is not very good (maybe like the real plane?) at descending in VNAV if an early descent has been engaged prior to the ToD.

Ghiom

[Ray Proudfoot 8,921]

Which ToD? The CDUs or RC's? Either way you cannot remain at cruise once you have acknowledged the command to start your descent.

 

That's why we put the PD option there.

[ghiom 2]

the CDU's...

Yes, I need that PD option.

[chrispeel 0]

Evening Ray from a windy North Staffs

 

Following on from this topic I experienced this recently.More than once but not every time:-

 

I am in cruise at say FL390.I get told to descend to FL370.But as it's a "wrong way round" landing direction  I request a PD as I'm still 60nm to go to TOD.I receive the approval.Shortly after I get a "When Ready" clearance to FL350.I acknowledge but remain at FL390 as it was not an instruction to descend and I'm not ready.But then very soon after I am scolded as I haven't descended.To repeat,the PD was approved and the next instruction was When Ready.So I think I am complying.

 

If I ignore the last I receive constant orders to descend.

 

I am following the RC4 filed plan and have the comms.I am at the flight plan cruise level at the standard altimeter setting.

 

Any ideas?

[Ray Proudfoot 8,921]

Hi Chris,

 

Can't fathom that one out. As you say, if you're advised to descend at your discretion you should not be nagged. The only thing I can think of is if there was a change of wind and you then needed a near-side approach. You would then need to start the descent earlier. That might explain why but it's a guess in the dark without a log.

 

If you feel you can replicate it create a log and send it to JD using the guidance pinned on the forum.

 

Windy here too as you can see in my sig.