Avare Airport Performance/Density Altitude Calculations

[Craig Richardson]

I have been using Avare and find it to be a phenomenal tool for flight planning and situational awareness.  One thing I have noticed is that as the temperature drops below freezing, i.e. 0*C, I notice that the density altitude calculation, listed as Performance when you long press on an airport with METAR appears to go up, not down.  My guess is that Avare is not properly taking the negative temperatures into consideration.  METARs list negative temperatures with an M preceding them, rather than a negative (-) sign.  I am not a coder or computer person at all and was wondering if there was anybody that knew about this potential error.  Is there anywhere to submit a bug report?
 
As an example, the field conditions at my home airport are field elevation, 2432 ft, air temp -02*C, dewpoint -03*C, and altimeter setting 30.17" Hg.  Avare is currently showing density altitude performance at 1100 feet.  If I use a different density altitude calculator, I come up with a density altitude figure of closer to 700 feet (729 feet, specifically).  If I manually run the same numbers dropping the negative signs on the temperature and dewpoint, making them positive, I get a density figure of 1200 feet, (1262 feet specifically).  This second number is not the same as the one given by Avare, but is much closer to the 1100 foot figure given.

[Zubair Khan]

Hello Craig
Thanks for reporting. The parsing issue has been found as you thought it would be. It will be fixed in next release. Relieved that the error is on the safe side.
Z


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-------- Original Message --------

On Dec 9, 2016, 2:33 PM, Craig Richardson wrote:

I have been using Avare and find it to be a phenomenal tool for flight planning and situational awareness.  One thing I have noticed is that as the temperature drops below freezing, i.e. 0*C, I notice that the density altitude calculation, listed as Performance when you long press on an airport with METAR appears to go up, not down.  My guess is that Avare is not properly taking the negative temperatures into consideration.  METARs list negative temperatures with an M preceding them, rather than a negative (-) sign.  I am not a coder or computer person at all and was wondering if there was anybody that knew about this potential error.  Is there anywhere to submit a bug report?
 
As an example, the field conditions at my home airport are field elevation, 2432 ft, air temp -02*C, dewpoint -03*C, and altimeter setting 30.17" Hg.  Avare is currently showing density altitude performance at 1100 feet.  If I use a different density altitude calculator, I come up with a density altitude figure of closer to 700 feet (729 feet, specifically).  If I manually run the same numbers dropping the negative signs on the temperature and dewpoint, making them positive, I get a density figure of 1200 feet, (1262 feet specifically).  This second number is not the same as the one given by Avare, but is much closer to the 1100 foot figure given.

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