[Antennas] VHF Antenna for aircraft bands

[Richard Greaney]

Hi all
I have recently moved houses and have lost coverage of my local airport 
tower. At my previous place, i was able to use the TV antenna as this 
was pointed in roughly the right direction. It also helped that i lived 
closer.

However, now I have moved to a spot where the heading difference between 
the TV transmitter and the tower is too great, so I need to setup my own 
antenna. I live 7.5km from the airport, and if I climb up on the roof I 
don't have line of sight coverage, however it is a flat city so it's 
mostly rooftops and trees in the way. My question is, before I go 
spending any money, would I have much luck using a fringe TV antenna 
with something in the area of 10dB gain?

I'd appreciate any advice people might have on this.

Cheers
Richard