Figured out GTN Trip Planning Page Strangeness

[Pinecone]

@TrekLawler

Ok, it has been bugging me for a while that when I would go to the Trip Planning page, it would show me an ETA that was before the actual time. 

So coming back from Mooney Max, I played with it and figured it out.

If you do a Trip Plan from Present Postion to your destination, it gives an accurate ETE, but the ETA is calculated from the Take Off (power on) time, NOT the present time.

If I am Trip Planning from Present Position, it seems it should use Present Time.

In the picture below, the Take Off time was 10:53.  The Present Time was 12:38.  ETE shows 3+49, but ETA shows 14:42, or 2 + 06 from present time.  But the correct ETA if I was taking off at 10:53.

 

 

[PT20J]

Sounds like a bug. I’d send it to Garmin support. They have fixed some things I’ve complained about in the past. 

[Pinecone]

That is why I pinged Trek.

[PT20J]

You might want to email him directly. He doesn’t check in here often.

[TrekLawler]

my best guess at this point is there is an input missing somewhere on this planning page which is preventing this from calculating correctly. I just did a number of flight scenarios with some of our test kiosks myself and our pilot operations team and in every case the ETE was calculating correctly and counting down during our flights. I also asked one of our test pilots to look at this on a morning test flight in one of our planes and it is working correctly.

[Pinecone]

@TrekLawler

The ETE is correct, but the ETA is not.  The ETA from Present Position is ETE from PP added to the TAKE OFF TIME, NOT the current time.

So if you took off at 10:00 and had an ETE from Present Position of 1 hour, at 12 Noon, it would say your ETA is 11:00,   Hmm, time warp.

 

[TrekLawler]

1 hour ago, Pinecone said:

@TrekLawler

The ETE is correct, but the ETA is not.  The ETA from Present Position is ETE from PP added to the TAKE OFF TIME, NOT the current time.

So if you took off at 10:00 and had an ETE from Present Position of 1 hour, at 12 Noon, it would say your ETA is 11:00,   Hmm, time warp.

 

OK, I follow you now with what you're describing. this is not any kind of fault in the software and normal operation. the field for the time of departure is always a pilot input field. you as the pilot are required to input your time of departure for the system to accurately calculate this.

[midlifeflyer]

2 hours ago, Pinecone said:

@TrekLawler

The ETE is correct, but the ETA is not.  The ETA from Present Position is ETE from PP added to the TAKE OFF TIME, NOT the current time.

So if you took off at 10:00 and had an ETE from Present Position of 1 hour, at 12 Noon, it would say your ETA is 11:00,   Hmm, time warp.

 

Let's go back a page.  This is not a currant flight plan, based on what's happening now. It's a planning tool, "for planning purposes only."  Buried in Utilities, not up front like things for immediate use. Like most planning tools, whether online, in an app, on paper, or as part of an FMS, it is based on what you tell it. Here's the page before the one you posted. It does automatically populate the Depart Time and the Depart Date with "now" when you first go there, but that's just a convenience on the assumption that you are not planning a flight for some time in 1991. It's not a clock  that updates as you go along. It's looking for you to enter the date and time of the flight you are planning to take. Notice that it even asks you to enter your expected ground speed. If you are leaving in ah hour, put that time in. If you are doing the flight next week, put that one in. 

I've never been that impressed. There are better advance planning tools. And I guess an option to keep updating the clock would be useful if you were using it to calculate a casual diversion but, as far as I can tell, it works as advertised.  

[Pinecone]

7 hours ago, TrekLawler said:

OK, I follow you now with what you're describing. this is not any kind of fault in the software and normal operation. the field for the time of departure is always a pilot input field. you as the pilot are required to input your time of departure for the system to accurately calculate this.

You are missing the point.  The unit auto fills in the departure time.  Which is fine.

But if I calculate based on my Present Position, it should use the PRESENT TIME.  You are at your present position NOW, not at your departure time.

And I will have to double check, but I tried to change the Departure Time and was not able to

[Pinecone]

6 hours ago, midlifeflyer said:

Let's go back a page.  This is not a currant flight plan, based on what's happening now. It's a planning tool, "for planning purposes only."  Buried in Utilities, not up front like things for immediate use. Like most planning tools, whether online, in an app, on paper, or as part of an FMS, it is based on what you tell it. Here's the page before the one you posted. It does automatically populate the Depart Time and the Depart Date with "now" when you first go there, but that's just a convenience on the assumption that you are not planning a flight for some time in 1991. It's not a clock  that updates as you go along. It's looking for you to enter the date and time of the flight you are planning to take. Notice that it even asks you to enter your expected ground speed. If you are leaving in ah hour, put that time in. If you are doing the flight next week, put that one in. 

I've never been that impressed. There are better advance planning tools. And I guess an option to keep updating the clock would be useful if you were using it to calculate a casual diversion but, as far as I can tell, it works as advertised.  

Except it will calculate from Present Position.  So it is expected to be usable in flight.

It also allows calculation from Present Position to any fix that is entered in the Flight Plan.

Yes, it can be used pre-flight using the Point to Point entry.

[midlifeflyer]

12 hours ago, Pinecone said:

Except it will calculate from Present Position.  So it is expected to be usable in flight.

It also allows calculation from Present Position to any fix that is entered in the Flight Plan.

Yes, it can be used pre-flight using the Point to Point entry.

That's why I thought it might be helpful to have a moving clock. 

But I also don't see much in-flight usefulness for it to begin with. So, aside from that feature, I'm wondering what  you actually  use it for in flight that wouldn't be accomplished in the current flight plan or catalog. Practical question.

[Pinecone]

I can easily look at ETE and ETA to any given fix.

[Pinecone]

@TrekLawler From over on BT, here is the info from the manual, which says in flight from Present Position is uses Current Time.

So the units do NOT work they way that Garmin say they do, so it is a BUG.