Question: how fast can dbz characters fly?
Answer: Snake way was 1 000 000 km long which means, Goku at PL 5000 can fly around mach 30. [Just as a side point to estimate how fast Vegeta "might" be-if Goku with a 5000 PL can fly at Mach 30 I will say Vegeta with a PL 18,000 in the Saiyan saga might be Mach 66=50,237 Mph.