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ghiom

How to delay the descent?

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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."

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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.

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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.

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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.

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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

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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...

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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?

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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...

 

.

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

 

Yep

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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.

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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

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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.

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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?

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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.

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Chris,

 

One other thought on your problem. Did you have a 40 mile / FL120 waypoint restriction in the CDU? If not then you will almost certainly have an incorrect ToD point.

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Thanks for the replies Ray.

 

I tried to get back to you last night but couldn't get in to the site

 

You may have got  the answer with your first comments regarding a change in runway.And I tend not to place an altitude restriction in the FMC which may explain something but would it explain the nagging after a "when ready" instruction?I always have the comms at the TOD as a rule and if I don't want to be at the 12000 mark I tell them I am unable.

 

I am currently approaching BHX from the south and expecting RW 15 as the winds are from the south.I ask for a PD and get it.Immediately after that I am getting the "when ready"

 

The only work around is to ignore it! Or accept it and be way too low too soon.Or do it very very slowly as you have recommended many times

 

 

 

 

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And I tend not to place an altitude restriction in the FMC which may explain something but would it explain the nagging after a "when ready" instruction?I always have the comms at the TOD as a rule and if I don't want to be at the 12000 mark I tell them I am unable.

I am currently approaching BHX from the south and expecting RW 15 as the winds are from the south.I ask for a PD and get it.Immediately after that I am getting the "when ready"

The only work around is to ignore it! Or accept it and be way too low too soon.Or do it very very slowly as you have recommended many times

 

Hi Chris,

 

If you don't enter the crossing restriction as a waypoint in the CDU the calculated ToD will always be closer to the airport than the one calculated by RC. When you were instructed to descend yesterday to your surprise it's because RC calculated that you needed to start down then to have a chance of reaching the crossing restriction altitude in time. I now understand why that instruction was given.

 

It's entirely up to you if you want to add that waypoint to your plan but you may find it helps with the descent phase. I use the FIX option and enter /41 which gives me an extra mile for the speed to drop away for a near-side approach when 250kts is the maximum speed allowed. The arc also gives me a visible indication of where I need to be and the altitude I must attain.

 

I tend to leave comms to Otto so when I'm cleared lower sooner than the CDU has calculated I just start a gentle 200/min descent until such time as the CDU calculates I need to start the descent proper.

 

There are no fixed rules about descents except the one where you must be at the correct altitude 40 miles from arrival. How you get there adds to the fun for your passengers! :BigGrin:

 

It's even more fun with Concorde when the descent rate often reached 6,000fpm but I still have to achieve that restriction.

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Thanks Ray.I've been away for a few days hence the failure to reply.

 

I have been using RC 4 for an awful long time and I have become used to its idiosyncrasies if I may call them that.So I sometimes work round the rather artificial 12000 foot rule in the way you have often suggested.Another way is to make every airfield an  altitude restricted one by using Notams.

 

No,my initial query was about this strange use of the "when ready" command after requesting a PD,having that accepted then getting this "when ready"very soon after the PD approval.To me this makes it entirely optional.It happens many times in the real world too.But when acknowledged RC4 will frequently(but not always)hassle me to do it!

 

Also this never seems to happen when the "when ready" instruction happens at lower levels later in the descent phase

 

 

 

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Hi Chris,

 

Not sure what I can add to this issue. Without being able to see the source code I can only reiterate my earlier assumption that in order that your aircraft can reach the crossing restriction you need to start your descent when RC says. Maybe we should have added "discretion request cancelled, start down now please".

 

Out of interest did you manage to reach the crossing restriction when you ignored RC and if so, what was your maximum descent rate? Aircraft type would be helpful too.

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Evening Ray

 

The crossing restriction thing is not really my issue.I don't think its very realistic but one lives with it for the sake of the exercise.I cope with it.If landing wrong way round so to speak it is usually way out.

 

The "when ready" instruction usually occurs when the initial descent is to say FL370 from FL390 by the way.Followed quickly by the "when ready" to FL350.That is the usual scenario.

 

I'm using the PMDG 738 at the moment but also use the LD B763 and the PMDG B744.All the comments relating to this weird "when ready" thing are with the aircraft descending from high altitude trips.i.e.FL 370 or higher.

 

Another thing I now sometimes experience is very late landing clearances.Sometimes after I've landed!This is not the real world so yes I do land.I'm up to date with rebuilds and the like by the way.I have a feeling I may have corrupted RC 4 somehow!

 

Better now the real world wind has dropped isn't it?There were some hairy moments at EMA the other night.

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The crossing restriction thing is not really my issue.I don't think its very realistic but one lives with it for the sake of the exercise.I cope with it.If landing wrong way round so to speak it is usually way out.

 

RC uses a simple 1 in 3 rule so it usually wants you to start down before the CDU. But as John and Doug used to say - controllers control, not CDUs :smile:  If you want to contact APP you have to meet that crossing restriction. You know that of course.

 

The "when ready" instruction usually occurs when the initial descent is to say FL370 from FL390 by the way.Followed quickly by the "when ready" to FL350.That is the usual scenario.

Same for me as I fly the 737-800.

 

I'm using the PMDG 738 at the moment but also use the LD B763 and the PMDG B744.All the comments relating to this weird "when ready" thing are with the aircraft descending from high altitude trips.i.e.FL 370 or higher.

You didn't mention descent rates but with those heavy aircraft I imagine overspeed might be a problem if you're leaving the descent very late.

 

Another thing I now sometimes experience is very late landing clearances.Sometimes after I've landed!This is not the real world so yes I do land.I'm up to date with rebuilds and the like by the way.I have a feeling I may have corrupted RC 4 somehow!

Sounds like RC4 is fighting for resources if you run it on the same computer as FSX. And maybe lots of Ai too. This is where a WideFS PC can help. Doubt RC is corrupted - just fighting for resources.

 

Better now the real world wind has dropped isn't it?There were some hairy moments at EMA the other night.

I must have missed the fun. But lighter winds are welcome.

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Re: Late landing clearances

 

Be sure your flight plan, FMS data, and scenery data (RC Scenery Rebuild) match so RC has your correct FS location in regard to the extended center line. There are two landing commands - one further out on final than the final cleared to land about three miles out or so. RC needs you to be on its calculated runway center approach line.

 

There are some FS tech influences that can cause a location disagreement. One prominent one is the replacement of the magdec.bgl in FS\scenery\base\scenery by various updates. This can cause default navaid orientation to be out of sync with the navaids and aircraft RAW navigation instrumentation due to the difference in navaid mag deviation properties and runway geographical alignment. This was discussed in the FS9 PMDG B737 forums quite long time ago. Some scenery add-ons update that file to match their scenery but messing up other scenery.

 

I've had the late "Cleared to Land" final statement in FS9 just a few times when something slowed my aircraft or comm responses. Unlike most the flying in RCC, RC will not give you correction vectors if you miss the center-line intercept but just does not recognize that you are on it according to my experience.

 

Re: "When able"

 

. . . is also used with NOTAMS enabled for the destination airport. (NOTAMS does not relieve the crossing restriction altitude by the way.) There can be confusion here.

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Thanks Ronzie

 

 Re late landing clearances I'm pretty sure its not a comms problem and I am usually pretty confident with ILS approaches,But I think you may have hit the nail on the head with the reference to tech issues

 

Reference "when ready" it is an  initial descent thing and not related to Notams.I hear what you say about the 12000 restriction and that was my mistake for mentioning it in that context.

 

Ray.Thanks also.Are you saying to place a 40 mile point in the FS flight plan?Or the CDU.I have played with it in the FMC but usually cope OK without it.

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Ray.Thanks also.Are you saying to place a 40 mile point in the FS flight plan?Or the CDU.I have played with it in the FMC but usually cope OK without it.

I place it in the CDU as a 'virtual' waypoint. Use the FIX option to create one 41 miles out. That gives the aircraft a little time to slow down. If you don't create one how do you know the point where you have to be at the commanded altitude / FL?

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