The math to verify Mr. Philip Johnson is given below. The maximum bank angle for a normal category aircraft is 60deg at 2G's. The formula for turn radius is
V^2
R = ----------
G*tan(bank)
given
V=168900(ft/sec) = 1000kt * 1.68
G=32.2(ft/sec)
tan(bank) = 1.7(60deg)
R=(1690^2) / (32.2 * 1.7) = 52175(ft)
9.8(radius) x 2 = 19.76.4mi