flyboy, have a good plan, many plans; you can’t plan enough, consider the what-ifs, alternatives, last minute changes, etc.
Check with the authorities, local regulations, and any special conditions that might apply to the demonstration. Weather minima; yours should probably be greater than the airshow organisers.
Ask to see the safety plan, and enquire how this might affect you; what clearances, approvals etc, are required. Check any restrictions on passenger carriage; generally restrict the flight to crew only.
Check the location very carefully, particularly obstructions and terrain; these will not have the same relevance as in normal operations; look at operational aspects from a different perspective.
The airshow attendees want to see the aircraft for what it is, so show it. Consider a shallow arc across the front of the crowd line with the wing down – don’t attempt clever top rudder manoeuvres or wing rocking.
A big aircraft will never look as fast as smaller ones, so choose a moderate airspeed. It will appear faster when flown downwind. In a hot climate there may be thermal turbulence so consider a speed just above rough airspeed, also note the 60 deg bank (2g) stall speed, fly at or above this speed to give manoeuvre capability; consider a small flap setting if appropriate.
Consider the bird strike risk – more people, more food = more birds. Maintain level flight thrust, don’t throttle back for a quiet fly by – you will be quieter relative to any military aircraft.
Altitude, 300ft min, 500ft will look OK. Consider where the public are and that some people might be viewing from the far end of the airfield. A big aircraft will look low even above 500ft as it should differ from their normal perception.
Give yourself time (speed) and altitude margin, and good weather to enjoy the flyby and counter any surprises … loose balloon, gliders, an errant helicopter, or helicopter in ground-hover throwing up dust and debris. Wake turbulence.
Don’t fly towards the public inside the area of a normal circuit; use a long final and early line up; arc in from behind the extended crowd-line, exit similarly.
Check the aircraft systems which might throw up unwanted alerts or changes – ditch the FMS. Switching off the EGPWS might only disable the enhanced functions, thus ‘too low flaps / gear’, 'bank angle', ‘pull up’ might sound, check the specific installation. Set DH call out 50 ft below you minimum.
TCAS/ACAS ?? Be ready for surprises … then #1 fly the aircraft.
Construct a checklist of systems to ‘reconfigure’ or issues to be aware off. Construct and use a post fly-by checklist to reset the aircraft to its normal state as soon as practical.
Allocate specific crew responsibilities for monitoring and call outs – altitude, speed, bank angle.
Define the safety boundaries and the margins from them. Check the fuel plan, what margin is there for change; where’s the holding area, safety height, clearance form other aircraft, radar surveillance, ...
Few airshows run to time. ‘No plan survives contact with the enemy’.
But above all else … plan, so that you can enjoy the experience.