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Can a jump pack enabled character heroically intervene over models.

Yes. Heroic Interventions happen in the Charge Phase, and this is the relevant part of the current version of the FLY rule:

"If the datasheet for a model says it can Fly, then during the Charge phase it can move across models (other than Buildings) as if they were not there"

As Stux says, FLY works in the Charge phase the same as the Movement phase with the exception of BUILDINGS.