correct as is WPT and TCN Descent Guidance Different Distances

[Frederf]

Not sure if it should be the same for both modes but currently TCN and WPT descent guidance is giving different distances with TCN having the steeper approach. In example track waypoint and TCN are colocated. WPT guidance is 30nm while TCN guidance is 24nm.

F18WPTTCNDescent.trk

[TimRobertsen]

In the Persian map, this number puts you at point of about 5900 feet MSL above the tacan.

In the Caucasus map, this number puts you at point about 6600 feet MSL above the tacan.

 

In both maps, this is regardless of the tacan’s elevation, and regardless of whether it is a carrier-tacan and airfield-tacan.

[Frederf]

Interesting. That would explain the closer distances. TACAN position is defined inside the airplane data so it knows the station elevation. That ~6kft would be an intentional feature. What I don't understand is why TACAN would have the extra height at end of descent and waypoint would not.

[TimRobertsen]

What confuses me is why there is a difference between the maps.

 

But, it seems this is correct, for some reason

[norman99]

If this is "correct as is" can someone from ED please explain why?

 

It's all great having something correct, but when we the "customer" questions things, it would actually be helpful if it was explained why it's correct, and how the function in question is supposed to operate.

 

Personally, I'm getting a little tired of "correct as is" without so much as a sentence describing the correct behavior.

 

Just a thought....

Edited March 23, 2021 by norman99

[dorianR666]

On 2/26/2021 at 12:56 PM, TimRobertsen said:

What confuses me is why there is a difference between the maps.

indeed

 

i would also like an explanation why this function works differently depending on terrain module used.