you have two choices for runway.. take off or landing shots.. decide first and foremost what you want to get.. air shots it doesnt matter where you stand.
for camera settings a good guideline is the following
Focus set to AF
Centre AF focus point selected only
AI Servo Mode
Evaluative Metering mOde
generally best to shoot in TV ( Shutter Priority Mode )
AUTO ISO
Continuous shooting mode
Shutter speeds
fast jets 1/800th to 1/1200th
fast jet blurred backgrounds 1/500th
Prop aircraft between 1/125 and 1/250 ( depnding on prop.. bi planes the slower speed , spitfires and the like the faster speed
Prop Helicopters between 1/60th and 1/125th depending on speed of rotation
try and keep below ISO 400 if you can though on a sunday day auto ISO is fine and try keep between f/5.6 and f/8 .
again not easy when using TV ( Shutter priority ) but again dpends on weather conditions
And of course make sure you have spare batteries, plenty of SD cards ( i used 3 cards for Biggin Hill festival a couple of weeks back and took over 2000 shots )
and enjoy!