How do you get to the flying Pokemon leader in black?

You can't actually "get to" the Flying-type Gym Leader in Pokemon Black, because there isn't one!

There is no Flying-type gym leader in Pokemon Black or White. The gym leaders in those games are:

* Cheren: Normal-type (Striaton City)

* Lenora: Fighting-type (Nacrene City)

* Burgh: Bug-type (Castelia City)

* Elesa: Electric-type (Nimbasa City)

* Clay: Ground-type (Driftveil City)

* Skyla: Flying-type (Mistralton City)

* Cilan: Grass-type (Opelucid City)

* Shauntal: Ghost-type (Undella Bay)

* Marshal: Dark-type (Icirrus City)

* Iris: Dragon-type (Dragonspiral Tower)

If you are thinking of another game in the Pokemon series, please let me know!