Lift is a physics effect of moving air that can be manipulated by an airborne vehicle and its pilot. Depending on the angle of the wings attached and the angle of flight direction, lift can gain in strength or weaken. Similar to how buoyancy works, in that water pressure pushes up on an object to stop it from sinking, lift involves air pressure that pushes up on the plane or aircraft in relation to its weight and speed.
As noted, a number of factors influences the amount of lift an aircraft will experience while operating. Assuming thrust and weight are acceptable to stay in the air and not fall to the ground, the direction angle of the aircraft will also influence the amount of lift. When the plane goes downward, the pilot is letting gravity take effect to pull the plane towards the earth. When the plane is climbing, the pilot is using lift to raise the plane higher in altitude. However, the angle cannot be too steep or the risk of falling out of control or stalling while climbing can occur.
An angle that is too steep for an aircraft to climb is known as the critical angle of attack. Beyond this point, which for many planes is about 20 degrees, the engine could stall and stop or the plane can lose its momentum and begin to fall due to gravity. Going downward, the plane can be in a much steeper angle but the pilot then has to remember that he will still need room to climb out of the fall. Too steep a return and the stalling problem can occur again.
Every pilot operating a plane or aircraft vehicle must understand how lift interacts with an aircraft since it basically prevents the plane from crashing to the ground. As a result, both pilot training and pilot license testing focus on the student's ability to manage lift and what to do when changes occur due to changes in flight angle as a result of direction or mechanical failure. Knowing how to fix these problems ahead of time can avert accidents that can be fatal.
