We do not expect you to complete a mission if weather (or any other factor) is going to make your flight unsafe. If you are interested in signing up for a mission, but are hesitating because it is looking like weather may be an issue the day of the mission, or the mission is far in advance and you don't know what weather will be like that day, we encourage you sign up anyway. Any other pilot who signs up may also have to end up cancelling. Our passengers are educated about the possibility of cancellations, and are expected to have their own plan B in place or to work with AFW on a plan B.
If you do have to cancel, we can look for a replacement pilot if you think another pilot may be able to complete the mission safely (for example, if you are a VFR only pilot and it's looking like IFR conditions). AFW typically will not ask any pilot, regardless of aircraft type, to fly into known icing.
The Passenger Assistance Fund (PAF) is another way that AFW can back your flight up. While not every flight can be supported with a backup (for example, for those passengers who live in remote areas without access to public transportation), many can be, and for those that cannot, the passenger is aware of the possibility of having to reschedule their appointment.