In a banked turn at constant altitude, the load factor is equal to 1 cos ⁡ ⁡ θ θ . We can see that the load factor in straight and level flight is 1 , since cos ⁡ ⁡ ( 0 ) = 1 , and to generate sufficient lift to maintain constant altitude, the load factor must approach infinity as the bank angle approaches 90 ∘ ∘ and cos ⁡ ⁡ θ θ approaches 0 . This is physically impossible, because structural limitations of the aircraft or physical endurance of the occupants will be exceeded well before then.