T/D and VS calculate

[utah77]

Hello.

Sorry for bad english.

Please write the formula for calculating the T/D and calculate the vertical speed.

As far as I know, the CRJ FMC can automatically calculate T/D and show the profile of descent.

Tahnks.

[cessna729]

Please write the formula for calculating the T/D and calculate the vertical speed. As far as I know, the CRJ FMC can automatically calculate T/D and show the profile of descent.

Hi utah77, Not too sure what you mean by "T/D", if you mean "Top of Descent", have a look at the CRJ200_Tutorial_1.1.0.pdf, on page 42, where Javier describes the following:

We are going fast and we are going high. Soon we will need a descent. This plane don’t have (still) VNav advisory so we have to calculate when make the descent. There is an easy formula to do that.

Distance from altitude to reach = (Altitude Difference/1000) x 3

Well it is easier than imagine. We are going to put an example, with this flight. We are at 24,000 feet and looking at the STARs map we need to be above 6000 feet between CENTA and CLS. So we choose to be at 10,000 over CENTA. When should we start our descent to reach CENTA at 10,000 feet? Easy:

Altitude Difference = 24,000 - 10,000 = 14,000 (we need descent 14,000 feet) 14,000/1,000 = 14 14 x 3 = 42 we need start our descent 42nm from CENTA.

And the descent rate needed? Easy formula also:

Descent rate needed = (Ground Speed / 2) x 10

We will see our ground speed near those 42 nm to CENTA

cessna729.

Edited April 20, 2012 by cessna729

[utah77]

Thanks for the reply but you did not answer the question of the automatic calculation of points. Several times I flew with a crew of Belavia, and saw clearly that the Top of Descent (yes, it is called T/D!) point on the display.

Without a full FMS this aircraft is not worth the money. The visual model is worthless without the full operation of all systems.

Will the added features do not work in future patches?

Edited April 22, 2012 by utah77

[Japo32]

We don't know if we will put the Vnav advisories in future patches or not. I know the real plane have those features, but they where not as important as others to make function in the FMS and navigation of the real plane. For me was more important to dedicate time in a Holding page than in the Vnav one, because with the formula it is good to make the calculations decending or ascending.

If we include the vnav advisories in future (that already have something when loading the SIDs and STARs) then of course we will add the ToD feature.

But for now that is something we don't know if we will include, because we are fixing the small number people that find bugs.

[utah77]

I see.

But do at least an opportunity to get the distance to any point. This feature is in a real FMS under PERF.

[philipp]

Thanks for the reply but you did not answer the question of the automatic calculation of points. Several times I flew with a crew of Belavia, and saw clearly that the Top of Descent (yes, it is called T/D!) point on the display.

Without a full FMS this aircraft is not worth the money. The visual model is worthless without the full operation of all systems.

Will the added features do not work in future patches?

I have to object to what you call "full FMS". The actual capabilities of the FMS depend on what the customer (the airline) ordered. The Collins FMS4200 that is in the CRJ has NO authoritative VNAV. If it is there, it is ADVISORY only. Therefore, it is not uncommon for an airline to not order the feature at all.

Here's what a real CRJ pilot said while we were developing the CRJ for X-Plane

Regarding VNAV, its advisory only, the interface is actually inop. on our equipment. Which prohibits the A/P from following any VNAV commands the FMC gives it. We use the cue/symbology for simple route/enroute planning and visual reminders only.

We still plot TOC and TOD the old fashion way, climb decent, crossing restrictions are all hand plotted and requires simple math on the part of the pilot to compute.

We alos have ALOT of other restrictions as well.

Such as GPS/RNAV approaches prohibited unless VMC and hand flown by the PIC.

That means this pilot's airline has those PERF pages INOP, and this is in no way different from our simulation.

I hope that clears things up: The FMS without ADVISORY VNAV is neither "worthless" nor "unrealistic" but a valid option that you may find in an early CRJ operated by an airline who chose not to buy the respective carrier options.

Philipp

[cessna729]

Thanks for the reply but you did not answer the question of the automatic calculation of points.

utah77, Sorry you're so unhappy with the answer I gave, but if you had taken the time to read it all, you would have been able to see on the first line of the quote from Javier's Tutorial.

This plane don’t have (still) VNav advisory so we have to calculate when make the descent.

You then go on to say.

Without a full FMS this aircraft is not worth the money. The visual model is worthless without the full operation of all systems

You entitled to your opinion, but in my humble opinion it is as a FULL implementaion of a FMS as you are likely to find on X-plane, and as Philipp & the "Real Operator's Guide FMS-4200 v4.0, Flight Management System for the Bombardier Regional Jet CRJ-100/200 by Rockwell Collins, Inc" say, VNAV is an option and not all "Real CRJ-200's" have it!

cessna729.

Edited April 22, 2012 by cessna729

[Kyle Sanders]

I love this aircraft and i LOVE the old fashioned way of doing things.... "yourself" lol.

But i have found that using the basic formula provided in the tutorial... i always end up about 1,000ft above where i want to be during descent.

For the tutorial... the waypoint was a FLY AT OR ABOVE i believe so it was ok but there are MANY way points that are stickily FLY AT.

Is there another formula that is a bit more accurate that anyone knows of?...

[cessna729]

But i have found that using the basic formula provided in the tutorial... i always end up about 1,000ft above where i want to be during descent......

Is there another formula that is a bit more accurate that anyone knows of?...

Hi Kyle, your not alone in pondering CRJ's descent performance, read what a "realworld" CRJ captain had to say about the "real CRJ".

cessna729.

[Kyle Sanders]

Hi Kyle, your not alone in pondering CRJ's descent performance, read what a "realworld" CRJ captain had to say about the "real CRJ".

cessna729.

Thanks for that. I am still wondering... he states in that article that "The CRJ200 has a descent planner"..... WHERE IS IT?!?!?!? lol I would VERY much like it.

[cessna729]

he states in that article that "The CRJ200 has a descent planner"..... WHERE IS IT?.

It lives behind this KEY on the CDU ,

it unlocks the following functions. plus alot of other clever stuff

Unfortunately, at the moment the VNAV key is not enabled yet in the JRollon CRJ

(see Javier's excellent CRJ200_Manual_1.1.0.pdf & CRJ200_Tutorial_1.1.0.pdf)

In this manual you will find on red colour which parts of the CRJ are STILL not simulated. And I must say “still” because my intention is to release future updates that would make this simulated CRJ closer to the real one. But I must say that because of the complexity of the plane this cannot be promised.

cessna729.

update: Just figured out what that magenta "arc" is for!!

The current JRollon CRJ-200 does have a similar capability. Say you have to decend, and be at a FIX e.g. PIERS at 8800ft ALT. (see pics below) It's a magenta line or arc that moves down towards the aircraft in MFD, its an indication of where the CRJ will be in terms of ALT selected if you maintain your current decent rate (eg -400 fpm), and it works very well. despite my poor flying, (see below). "I'd been wondering what that magenta arc had been doing for some time!.

Edited April 29, 2012 by cessna729

[Kyle Sanders]

It lives behind this KEY on the CDU ,

it unlocks the following functions. plus alot of other clever stuff

Unfortunately, at the moment the VNAV key & functionality is not enabled yet in the JRollon CRJ

(see Javier's excellent CRJ200_Manual_1.1.0.pdf & CRJ200_Tutorial_1.1.0.pdf)

cessna729.

Oh i understand now. Thank you! i hope this becomes a function here soon... it would be NICE lol

[cessna729]

Oh i understand now. Thank you! i hope this becomes a function here soon... it would be NICE lol

Hi Kyle, see update in post 11.

cessna729.

[Kyle Sanders]

It lives behind this KEY on the CDU ,

it unlocks the following functions. plus alot of other clever stuff

Unfortunately, at the moment the VNAV key is not enabled yet in the JRollon CRJ

(see Javier's excellent CRJ200_Manual_1.1.0.pdf & CRJ200_Tutorial_1.1.0.pdf)

cessna729.

update: Just figured out what that magenta "arc" is for!!

The current JRollon CRJ-200 does have a similar capability. Say you have to decend, and be at a FIX e.g. PIERS at 8800ft ALT. (see pics below) It's a magenta line or arc that moves down towards the aircraft in MFD, its an indication of where the CRJ will be in terms of ALT selected if you maintain your current decent rate (eg -400 fpm), and it works very well. despite my poor flying, (see below). "I'd been wondering what that magenta arc had been doing for some time!.

Yes i understand how the Magenta Arc works... It is a common tool used in many MFD but that is an "immediate" planning tool. which i LOVE but i still like to pretty much know my T/D before i even start up my computer and load x-plane. It is just the way i like to do things. "know my EVERY move before i even step into the plan".