On my current aircraft, which only has two packs, we regularly fly with only one pack on. This is with the knowledge and approval of the local regulators.
The aircraft can also be dispatched with only one pack operative without restrictions.
A slight change in Breecher's wording and the
Australian regulator allows it.
On my current aircraft, which only has two packs, we sometimes fly with only one pack on. The aircraft can be dispatched with only one pack operative with restrictions.
This is with the knowledge and approval of the local regulators.
Dash 8, BAe146, B717 + many more I am sure.