Fly: By means of this spell the user is able to fly at a speed of up to 12"/turn. The spell lasts for the number of turns equal to the level of the Magic-User plus the number of pips on a six-sided die which is secretly determined by the referee.There's really only three points that need to be discussed.
First: The spell specifies "user" instead of "caster", which differentiates it from Levitate. The person affected controls speed, altitude, and direction. There's no range listed, but a short range of 30 feet shouldn't be much of a problem.
Second: The max speed is another example of a "limit" stat, as described for Levitate. However, this limit is a flat Move rate of 12. It seems to be twice the speed of Levitate, so perhaps a base speed of 6 that doubles to 12 at 3rd level and 24 at 5th level would work. This may require reconciliation with other limits as we go along.
Third: The duration formula is yet another variant. It resembles Standard Physical (6 turns + caster level,) but the "6 turns" figure is transformed into "1d6 turns". The die roll is probably meant to add a bit of risk, but why is this not part of Levitate as well?