San Andreas 'Desert' missions

[Strider78]

 

If anyone assist with this, I would appreciate it.

 

Basically, I started the game again after getting so far and realising that I either did something wrong or must have missed something. So, two days of gaming later (days off work) I get back to more or less where I left off. Except that the desert missions are still not becoming readily available.

 

All of the bridges to Venturas and the other part are blocked off. To try to get over there means four stars of heat. The flying school is in the desert and that is the only way I am able to progess with the triad missions. The Toreno missions are the ones I am after, I really don't know what else I am supposed to do because the game is not readily leading me in his direction until of course you start playing driver for him, but that is a dead end.

 

I need the 'Desert' missions

 

I need access to that flying school, can anyone please tell me how I am supposed to progress.