Weather

[nebojsa milosavljevic]

Last week while online i had a chat with a new person about the Altimeter setting. I was asked,If you are not using real weather do you leave your altimeter setting at 29.92 all the time.I honestly did not know how to answer that. I always use real weather so i adjust it, but if not using real weather does it matter if you adjust or not.

 

nebojsa

[Randy Tyndall 1087023]

nebojsa,

 

Here's my take on real vs "clear" weather. The controlling side of VATSIM uses the real weather for the area they are controlling. Anywhere under the Transition Altitude (TA) for the region you are flying in your altimeter setting will affect the altitude the controller sees you at...I think. Above the TA, for any region, your altimeter should always be set to 29.92 (1013mb) so everyone will display to the controller at the altitude their aircraft altimeter shows them to be at.

 

That said, let's look at Controller using real weather with his "scope" (ATIS/METAR) set to the real world setting versus a pilot using "clear" weather with the altimeter set to 29.92 inHg all the time, both above and below the TA. Again, this is how I understand it and, of course, I could be wrong, as I frequently am.

 

I will use an airport I am familiar with, KBOI, Boise Air Terminal/Gowan Field in Idaho. The surveyed elevation for the airport is 2,871 feet above sea level. An aircraft sitting on the ground using real world weather with a properly set altimeter will display somewhere between 2800 and 2900 feet on their altimeter. That same aircraft using "clear" or no weather and an altimeter setting of 29.92 will still display somewhere between 2800 and 2900 feet MSL when sitting on the ramp at KBOI. Once that aircraft takes off, the altimeter for both situations will still read the actual altitude the aircraft is at so the controller should, I believe see it at the correct altitude.

 

The only times, I believe, the altimeter setting is an issue that affects the controller seeing you at an incorrect altitude are these;

 

One, using real world weather and not setting your altimeter to the real world altimeter setting.

 

Two, using no weather and setting your altimeter to anything other than 29.92 inHg.

 

Hopefully a Controller or Controller/Pilot will jump in here and verify or correct what I have said.

 

Randy

[Trent Hopkinson]

nebojsa,

 

The only times, I believe, the altimeter setting is an issue that affects the controller seeing you at an incorrect altitude are these;

 

One, using real world weather and not setting your altimeter to the real world altimeter setting.

 

Two, using no weather and setting your altimeter to anything other than 29.92 inHg.

 

Hopefully a Controller or Controller/Pilot will jump in here and verify or correct what I have said.

 

Randy

 

And 3: Using 'stuck' weather from a previous date (such as "real world weather updates" option in FSX, which stopped updating weather in about 2015 odd) and using... who knows what altimeter setting.

 

If you suspect your weather program has stopped updating properly (ActiveSky sometimes does this if your internet drops out and you haven't re-selected real world updates) then for FSX and P3D - try pressing the B key below 18000ft, and again when 'closer' to your arrival airport.