Why must aircraft generally be jacked indoors for weighing?

Jacking an aircraft indoors for weighing is primarily important to avoid air currents destabilizing the scales. When weighing an aircraft, precision is crucial to ensure accurate measurements. Air currents, whether from ventilation systems, open doors, or external weather, can affect the stability of the scales used to measure the aircraft's weight. These air currents can cause fluctuations or inaccuracies in the readings, leading to a potential miscalculation of the aircraft's actual weight.

While humidity issues, visibility, and temperature may have some impact on aircraft maintenance and operational practices, they are not the primary concerns when it comes to the accuracy of weighing an aircraft. The primary focus is on ensuring that the scales provide reliable and stable readings, something best achieved in a controlled indoor environment that minimizes external disturbances.