As a thought experiment, imagine a plane with minimal fuel/appliances on board with hundreds of heavy passengers that make up say 10% of the weight of the plane.
Now imagine that they have a way to synchronize a jump where temporarily for 0.5s they are airborne in relation to the plane.
(NOTE: If idea of so many heavy passengers is troublesome to you, assume this is a cargo carrier with spring loaded "widgets" that have ability to be programmed to "jump" at once.)
Can flight dynamics be affected due to the jump at ANY phase of the flight?
What % of the typical (cargo/passanger) plane weight is the actual cargo (excluding fuel)?
Does the location of the "jumping" cargo matter? Tail vs. Cockpit
What happens if all pax/cargo suddenly jumped to tail or cockpit section?