First, for this problem, we will need to know the formula for time dilation

Where t is the time in the reference frame on earth
t0 is the time on the ship
v is the velocity relative to lightspeed
and c is light speed in a vacuum
For this problem, we will need to convert .93x10^8 to a fraction of light speed.
.93x10^8 = .31c
Now, we can plug in the numbers we get from the given
t0 = 6 hours since the ship has been in the air for 6 hours

t = 6.31089
For the answer to be valid, we will convert .31089 to minutes by multiplying it by 60 (60 minutes in a hour)
18.654 minutes