code: def ground_height(self):
          '''return height above ground in feet'''
          lat = self.pkt['I105']['Lat']['val']
          lon = self.pkt['I105']['Lon']['val']
          global ElevationMap
          ret = ElevationMap.GetElevation(lat, lon)
          ret -= gen_settings.wgs84_to_AMSL
          return ret * 3.280f ground_height(self):
          '''return height above ground in feet'''
          lat = self.pkt['I105']['Lat']['val']
          lon = self.pkt['I105']['Lon']['val']
          global ElevationMap
          ret = ElevationMap.GetElevation(lat, lon)
          ret -= gen_settings.wgs84_to_AMSL
          return ret * 3.2807
docs: return height above ground in feet