In some cases when using barometric altimeter you may observe that altitude jumps suddenly several meters up and down when light changes (e.g. you open canopy or when clouds obscures sun).
This phenomenon is caused by light coming into pressure sensor through air hole. Electronic chip inside sensor is photo sensitive and direct sunlight may change its readings and results in altitude jumps.
To avoid this situation prepare small anti-light shield and glue it onto AP board to cover pressure sensor.