FSX Top of Descend Announcement Gauge

Fritz B. Hoering · 7 Mar 2016

Hi,

I am keen to put a XML gauge together that announces the top of descend about 40 miles away from TOD.

Does anyone have a clou which variables I could use to make it work?

Thanks in advance

Fritz

tgibson · 7 Mar 2016

Why do you want to announce top of descent 40 NM away from the top of descent? If that is what you want, I don't know of a simple way to do that.

dave hoeffgen · 7 Mar 2016

tgibson said:
Why do you want to announce top of descent 40 NM away from the top of descent? If that is what you want, I don't know of a simple way to do that.

Let's not ask why, let's see if it's possible.

Fritz B. Hoering said:
Hi,

I am keen to put a XML gauge together that announces the top of descend about 40 miles away from TOD.

Does anyone have a clou which variables I could use to make it work?

Thanks in advance

Fritz

So how is the TOD defined in your case? If it's just a distance from your destination (The descent distance) and you can access that one just add +40. Code the gauge to do the announcement when (Descent distance) + (40 miles) away from destination. In case the TOD doesn't exist yet you may have to calculate that one aswell.
I'm not an expert here but I hope this helps.
Gruß,
David

Heretic · 8 Mar 2016

Isn't this a bit pointless since FSX' and 3rd party ATC tools guide you down at their own discretion anyway?

Since your endeavour basically depends on the GPS, try Robbie McElrath's GPS guidebook (Google!).

There's a variable called (C:FS9GPS:FlightPlanWaypointRemainingTotalDistance, nmiles) that will show the remaining distance to your destination.
With a bit of triangulation, you can calculate the distance required to descend to your destination airport at an assumed rate of descent.
Then compare that calculated distance to the remaining GPS distance plus 40 and you should have your framework to play your announcement sound.

This code might or might not work. Check variable names and the tangent stuff against the SDK reference documents:

Code:

(A:INDICATED ALTITUDE, feet) 10000 &gt;
if{ 
(A:INDICATED ALTITUDE, feet) 3 dgrd tg / 0.000164579 * (>L:Projected Descent Distance, number)


(L:Projected Descent Distance, number) 40 + (C:FS9GPS:FlightPlanWaypointRemainingTotalDistance, nmiles) &lt;
(L:ToD Announcement Played, bool) ! and
if{ 1 (>L:ToD Announcement, number) 1 (>L:ToD Announcement Played, bool) } }

(A:INDICATED ALTITUDE, feet) 10000 &lt;
(L:ToD Announcement Played, bool) and
if{ 999 (>L:Projected Descent Distance, number) 0 (>L:ToD Announcement Played, bool) }

For good measure, the announcement will only play above 10000 feet and reset below.

The first calculation assumes a descent angle of 3°, converts it to radians and uses the tangent with the indicated altitude (in feet) to calculate a rough descent distance (in nautical miles).
The result is then, with a 40 nm bias, compared against the total distance to go. If the total distance is less than descent distance plus 40, the announcement is played once.

Fritz B. Hoering · 8 Mar 2016

Okay guys,

The reason to have the announcement is to get notified on the upcoming TOD when simulating with 4x, 8x or 16x rate. Getting notified on TOD, upon I would be able to reduce the sim rate to decent 2x or less.

In addition, I will try to create a gauge "Pause on TOD" about 20 miles away from TOD (in case I am not in front of my computer or diverted by the phone etc.). This feature is available in the PMDG 747 and the WILCO Airbus and really helpful, but coded in a DLL file.

I will try Heretic's code and let you know the test results.

Thank you so far.

rpmc · 8 Mar 2016

Heretic said:
Since your endeavour basically depends on the GPS, try Robbie McElrath's GPS guidebook (Google!).

GPS Guidebook

Bob

Heretic · 8 Mar 2016

Detecting the sim status to trigger pause is a bit tricky. The variable used in Doug Dawson's sound gauge doesn't work for me and I don't know if you're using XMLTools, which does now have a variable to detect the sim's status.

So the code uses a very simple method to detect pause.

Code:

(P:ABSOLUTE TIME,seconds) (G:Var1) ==
if{ 0 (>L:SimIsRunning,bool) }
els{ 1 (>L:SimIsRunning,bool) }
(P:ABSOLUTE TIME,seconds) (>G:Var1)

(L:Projected Descent Distance, number) 20 + (C:FS9GPS:FlightPlanWaypointRemainingTotalDistance, nmiles) &lt;
(L:SimIsRunning,bool) and
if{ (>K:PAUSE_TOGGLE) }

Make sure that you're not already using G:Var1. The projected distance is taken from the calculation in my previous post.

By the way:
The code I've posted has a huge drawback.
Exercise: Find the drawback and correct it.

chris · 9 Mar 2016

This is the code I use. It tells you the sim rate with 0 = paused.

Code:

<!-- Get Sim Rate -->
<Element>
  <Select>
  <Value>(E:ABSOLUTE TIME,Seconds) s0 (L:LastTime,Seconds) - (&gt;L:TimeDifference,Seconds) l0 (&gt;L:LastTime,Seconds) (L:TimeDifference,Seconds) 72 * near 4 / (&gt;L:SimRate,Number)</Value>
  </Select>
</Element>

Fritz B. Hoering · 9 Mar 2016

Thanks for the input.

@Heretic: None of the codes work, so I cannot find out the drawback.

@chris: Your code just readout the sim rate, but does nothing - right?

The FMC I'm using shows the flight levels on the waypoints along the route. I thought there might be a possibility to get the TOD from there, but no Clou how.

Not trivial ... Any other ideas or (code) suggestions?

COBS · 9 Mar 2016

It's quite complex as there are several steps required .

1. A nearest search for the "Destination" airport , and obtain the 'Elevation' of that airport.
2. Calculate the "3 degree glideslope distance" to about 2,500' above that airport elevation.
3. From the aircraft's final leg cruise altitude , subtract (2,500' + airport elevation) to obtain " Initial let down Height"
4. determine "Let down distance" by dividing "Initial let down height" by the average VSI to obtain "Let down Time".
"Let down time" multiplied by GS = "Let down distance"
5. "3 degree glideslope distance" plus "Let down distance" = "Total distance from TOD to airport"

6. In your case add 40 nm to "Total distance from TOD to airport" as the distance to trigger your advisory alarm .

Notes :
- The GS (Groundspeed) would be the cruise GS , unless a descent GS is nominated .
- The airport elevation is important as not all airports are at or near sea level , therefore it needs to be accounted for.
- The normal glideslope for approaches is 3 degrees , however the Let down phase would rarely match that angle , thus let down
needs to be treated separately.

Cheers
Karol
PS ;
The following link might be of interest ,
http://www.fsdeveloper.com/forum/threads/storage-of-gps-variables.433868/

specifically refer to reply #33 on the second page , covering Intercept position Height
above runway.

chris · 9 Mar 2016

@chris: Your code just readout the sim rate, but does nothing - right?

Yes, just an alternative (more generic) method to Heretics code for SimIsRunning.

Heretic · 9 Mar 2016

Fritz B. Hoering said:
None of the codes work, so I cannot find out the drawback.

Did you have a flight plan loaded in FSX' flight planner when testing it?

Fritz B. Hoering · 9 Mar 2016

@COBS (Karol): Wow, amazing! You must be a real expert! Unfortunately, this is far to complex for me. I just startet developing gauges and I am looking for solutions. I was wondering if somebody had already developed a Pause on TOD gauge to use it and substitute the pause with a callout and increase the distance. Thank you anyway!

@chris (Chris): Aha! Thx!

@Heretic: Yes, I had a IFR flight plan with waypoints (not direct GPS) loaded and was following it. From my CPL knowledge, I don't think there is a defined TOD if you fly VFR.

Heretic · 9 Mar 2016

Weird. This might need more investigation then.

Anyway, if you can't find a suitable solution here, try one of these tools:
http://library.avsim.net/search.php?SearchTerm=pause&CatID=fsx&Go=Search

Fritz B. Hoering · 9 Mar 2016

Thanks for the tool link. I will dig in it an let you know if it worked out.

Fritz B. Hoering · 10 Mar 2016

Nope, none of the tools helped to solve my issue. It looks like the xpause gauge has a Pause on TOD feature, but it is an external gauge, written in French. I tested it without success.

What I am looking for is an FSX internal gauge that pauses the sim on Top of Descent. Having that, it would be easy to make the callout just prior to reach the TOD.

Does anybody ever programmed a gauge for "Pause on TOD"?

COBS · 10 Mar 2016

Fritz B. Hoering said:
The FMC I'm using shows the flight levels on the waypoints along the route. I thought there might be a possibility to get the TOD from there, but no Clou how.

When you use the FMC to create a Flight Plan does that flight plan detail and show the TOD ?

If it shows a TOD , is that TOD a waypoint ?

If the TOD is a waypoint then it would have a Latitude and Longitude , in that case your project
would be easy to do using a Geocalc.

Cheers
Karol

Heretic · 10 Mar 2016

XPause is in English once it is installed and it has the exact features that you're looking for, including a ToD calculator with a distance offset.

Fritz B. Hoering · 11 Mar 2016

@COBS (Karol): No, the FMC just displays different FL/altitudes towards the targeted airport, not an exact TOD or waypoint like in the PMDG 747, Wilco Airbus or in the VASFMC.

@Heretic: As stated earlier, I'm looking for a gauge inside FSX. BTW: My xPause installation continues in French after install. I haven't found a way to switch it to another language.

Heretic · 11 Mar 2016

"Fichier" -> "Options" -> "Langue"

As you have seen in this thread, a gauge-based option is not easy to do, so it's either XPause or a long, rocky way to devise a working XML-based solution. I will not be part of the latter though. It's all up to you now.