So I just opened a new base airport, leased some planes and went to open anew route. However upon trying to open a new route I have no planes available, it appears they have been sent to my original base/HQ. Is it possible to transfer these aircraft to my new base and if so how do I do this?
You can't until they arrive.
Once they are there, select the aircraft, and in "manage aircraft", you'll see a "rebase aircraft" action. Choose memphis as a new destination, and you can now schedule the airframe.
What I have done in these situations is Swap the schedule of a current aircraft at your home base to the new aircraft and free up the existing aircraft which you can transfer straight away. Handy if your not around in 3-4hours! ;D