a/c= aircraft
plan b yak=another yak to consider since both containers are spoken for
alternative= same as above
The choice is up to you. If you want a Yak now, there are plenty to choose from. If you want the aeroworks Yak, then you will have to wait and see. Usually, not everyone that preorders actually purchases, something like 20-30%. So I guess you could say that you have a 20-30% chance of getting a Yak in this shipment if you preordered late.