Daniel B. answered 01/07/21
A retired computer professional to teach math, physics
Let
v = 300 m/s be the airplane's velocity,
g = 9.8 m/s² be gravitational acceleration,
a <= 4g be the maximum centripetal acceleration,
r (to be bounded) be the radius of the plane's turn.
The expression for centripetal acceleration is
a = v²/r
Applying the given bound
v²/r <= 4g
Simplifying
r >= v²/4g
Substituting actual numbers
r >= 300²/4x9.8 = 2,296m