How does ascents or descents affect an aircraft's weight?

The concept of weight in the context of aviation refers to the gravitational force acting on an aircraft due to its mass. This weight is determined by the aircraft's mass and the acceleration due to gravity, which remains constant regardless of the aircraft's altitude during ascent or descent.

As the aircraft ascends or descends, although the air pressure and temperature change, the mass of the aircraft does not change. Since weight is a product of mass and gravitational acceleration, it stays the same at different altitudes within the Earth's atmosphere.

Thus, even when an aircraft climbs higher into the sky or descends closer to the ground, the overall weight of the aircraft remains constant. This understanding is crucial for pilots when considering performance parameters such as lift, thrust, and fuel consumption, as the weight is a primary factor in these equations.