GTN Clock is One Hour Ahead

[RoundTwo]

6 hours ago, Marc_B said:

I checked this out this afternoon and realized that I was still on a MDT zulu offset and needed to update to MST.  I guess it's always right at least half the time!  But for flight I'm usually on Zulu as that's what ATC is always using so I have that shown on my Engine monitor under the elapsed flight time.

But I agree that if a Garmin GPS has a "local time" display, it makes complete sense that it should automatically show the actual local time unless you're in a hangar or don't have a signal.

I cried UNCLE and set it to UTC. 

[EricJ]

4 hours ago, RoundTwo said:

I cried UNCLE and set it to UTC. 

I can set my IFD to local or UTC or whatever I want, but I leave it on UTC.   It's still good for a timer, easy check of how many minutes past the hour, and most importantly for me, checking how old ATIS is.    For whatever reason I always wind up coming back to the home drome somewhere between ten minutes before the hour and five after, and I never know whether the ATIS is fresh or stale unless I compare it to the UTC display.   It's really handy for that.

[PT20J]

It's not a very smart clock. It doesn't change when flying across time zones either. I just set it to UTC. Done. I have a wristwatch for local time. 

[RoundTwo]

Just now, PT20J said:

It's not a very smart clock. It doesn't change when flying across time zones either. I just set it to UTC. Done. I have a wristwatch for local time. 

My poor little Aera 760 knows how to do it but not the big, brawny GTN. I guess it’s just another case of no attempt at consistency between divisions. 

[ArtVandelay]

My poor little Aera 760 knows how to do it but not the big, brawny GTN. I guess it’s just another case of no attempt at consistency between divisions. 

Could be a certified issue.

[EricJ]

7 hours ago, PT20J said:

It's not a very smart clock. It doesn't change when flying across time zones either. I just set it to UTC. Done. I have a wristwatch for local time. 

Or a phone, which is easy to set to adjust to local if you cross time zones if you want that.

[PeteMc]

Just now, EricJ said:

Or a phone, which is easy to set to adjust to local if you cross time zones if you want that.

Yea, but depending upon how high you fly, you will not have service.  And if you are low enough to just barely get service, you probably will drain the battery as the phone is constantly searching and trying to reconnect.  So one more unnecessary charge cycle and, oh yea, gotta remember to charge the phone. 

Best bet would be for Garmin to join this century and fix the issue.  Very simple to pull local time from the DB for the Wpt and Apts along your Route.  And I have to check...  Do the GTX375/GNC355/GPS175 have this same issue??

 

[PT20J]

I have a yoke mounted iPad running ForeFlight. With the G3X and GTN 650Xi, it is superfluous, but adds redundancy and I like the user interface. It happily keeps track of local time, so I set the panel avionics to UTC.

[Pinecone]

But what local time to display?  Departure?  Current Location?  Or Destination?

I just want them to fix the Flight Planning page ETA from present position.  Right now it calculates the ETA from from the ETE from PP to destination, but then does the offset from the take off time.

[PT20J]

3 hours ago, Pinecone said:

But what local time to display?  Departure?  Current Location?  Or Destination?

My iPad or iPhone knows GPS time and position, so it calculates proper local time accounting for DST and time zone.

3 hours ago, Pinecone said:

I just want them to fix the Flight Planning page ETA from present position.  Right now it calculates the ETA from from the ETE from PP to destination, but then does the offset from the take off time.

I'm not seeing your issue. The Departure Time is a user entered field. I believe the planner does fill it with actual departure time when you begin a flight, but thereafter, you need to enter it manually. So, if you are planning from P.POS to some waypoint it uses your GPS position as the start point and if you select Use Sensor Data it uses your GPS groundspeed, but you have to change the Depart Time manually. I believe that this is because it is a general purpose planner that can be used both in the air and on the ground and you might be planning some future flight. So, it has user entries for date and time. The Pilot's Guide pretty clearly states "Depart Time - Specify the departure time (local time at From waypoint)" in table that describes the modes.

 

[Pinecone]

1)  But walking or driving you are not covering several time zones, so which one do I want.  Last summer I flew non-stop Denver to Maryland.  Should my nav show Mountain time, Eastern time, or the time where the airplane is?   I can see arguments for all three.  So this way you choose.  

2)  So you take off on a 5 hour flight.  Go to Utilities -> Flight Planning.  It can do calculations of ETA, distance and such.  You have a choice of putting in locations or plan from the Present Position.  So you have been flying for 3 hours.  You want to see the data from where you are to your destination.  When you hit calculate, it figures you have a remaining flight time of 2 hours.  But the ETA is calculated from the take off (power on) time, which is HARD CODED.  So the GTN says you will arrive 1 hour before NOW.

If you read the manual, it says it calculates setups from Present Position using the Current Time, but it DOES NOT.

Pics below were from FL to MD.  It is telling me that my ETA is 14:42 with an ETE of 3:49 at 12:38.  If I had done this 2 hours later at 14:48, it would have shown ETE of 1:49, with an arrival of 12:42.  So I would arrive 2 hours in the past.  

Try it.  And no, you can't change the start time.

 

[PT20J]

Do you have a GTN 650 or a GTN 650Xi?

On the Xi, the Depart Time isn’t hard coded. It must be manually set to the correct time depending on the calculation you want it to make before you press Compute Data. If you are calculating from present position, you would set it to current time. 

I haven’t tried it on a non-Xi

EDIT: Here are a couple of screen shots from the Xi simulator app. The first shows the Depart Time button on the Trip Planning Page, and the second shows the data entry screen after pressing the Depart Time button.

Skip

[Marc_B]

I went out for a flight yesterday and realized there are three boxes I have to change for "Local Zulu offset".  ha ha ha.  But I have a Garmin watch and it changes the local time when it acquires GPS satellite.  So when I land, I put it in run mode, GPS acquired and time is automatically adjusted.

What do you think the purpose of having a Local Zulu offset is if it doesn't automatically adjust in an aircraft that is likely to cross time zones?  I'll have to check out Telligence commands to see if time is accurate...I think that you can "Say ETA at destination" and it tells you the local time of arrival I think?

I suspect this is an oversight from Garmin, not specifically functioning as intended.  And for the Trip Planning page, I personally think that Garmin should have designed it to use ONLY Zulu times with any of these calculations and screens to remove this ambiguity.

[Pinecone]

On 11/23/2023 at 11:06 AM, PT20J said:

Do you have a GTN 650 or a GTN 650Xi?

On the Xi, the Depart Time isn’t hard coded. It must be manually set to the correct time depending on the calculation you want it to make before you press Compute Data. If you are calculating from present position, you would set it to current time. 

I haven’t tried it on a non-Xi

EDIT: Here are a couple of screen shots from the Xi simulator app. The first shows the Depart Time button on the Trip Planning Page, and the second shows the data entry screen after pressing the Depart Time button.

Skip

 

I have an Xi.  I have to check again, but I have not been able to reset the start time.

But if I select from Present Position, why does it make me look up and enter the current time, as right now I am AT my Present Position.  

The manual says that from Present Position, it uses Current time, but it doesn't

[PT20J]

49 minutes ago, Pinecone said:

 

I have an Xi.  I have to check again, but I have not been able to reset the start time.

But if I select from Present Position, why does it make me look up and enter the current time, as right now I am AT my Present Position.  

The manual says that from Present Position, it uses Current time, but it doesn't

The manual isn’t terribly clear. It says ETA = Current Time + ETE …

It doesn’t say that you have to enter the current time except for the sentence that says, “Departure date and time and ground speed data are required independent of mode selection.” Also, the table says it’s a manual entry. 


I agree it could be better designed, and it certainly could better described in the manual, but I believe it works as designed.

Skip

[Pinecone]

1 hour ago, PT20J said:

The manual isn’t terribly clear. It says ETA = Current Time + ETE …

It doesn’t say that you have to enter the current time except for the sentence that says, “Departure date and time and ground speed data are required independent of mode selection.” Also, the table says it’s a manual entry. 


I agree it could be better designed, and it certainly could better described in the manual, but I believe it works as designed.

Skip

But it is not manual entry, as it auto fills the power on time.

It just makes no sense for it to not set the Current Time, when you select Present Position for planning.  

[Rick Junkin]

9 minutes ago, Pinecone said:

But it is not manual entry, as it auto fills the power on time.

It just makes no sense for it to not set the Current Time, when you select Present Position for planning.  

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