Having visited Southsea recently it doesn't seem the ideal spot for an air display. I wish them luck but I'm surprised they've got permission for it.
Southsea common is an excellent spot for it, plenty parking, trains, buses, bars, food, stalls, bags and bags of room to stand either on the beach or grass or sit and bbq, open sea for rescue displays etc, fair will be on for kids, great for photo taking, proper toilets

, simulators, rides, food village, rock/pop concert, fireworks ets etc etc. I've been to RIAT a couple times, long queue's to get in , very expensive, gave up on having a piss lol , long queue's to get out and expensive lol. Southsea should be a free event.

Check the Vid
http://www.portsmouthvideos.co.uk/attractions/18.htm