"sufficiently safe" is a correct and usable phrase in written English.
You can use it when talking about something that is safe enough to be considered satisfactory. For example, "The new playground is sufficiently safe for children to play in."
Although traditional validation process has historically produced sufficiently safe and reliable systems, they may be not sufficient for emerging Guidance Navigation & Control (GNC) systems, for new requirements for exploration missions or for next generation launchers.
If sufficiently safe, though, it might also be used in those with established infections.
Has the banking system been made sufficiently safe and healthy in the years since Lehman Brothers collapsed?
Your parental duty requires you to find not the safest conceivable mode of travel, but only one sufficiently safe.
NASA has not said how it would verify that commercial rockets were sufficiently safe for carrying astronauts.
Additionally, it was shown that the perfect bond assumption was sufficiently safe for the design of the GFRP RC slabs.
It all seems sufficiently safe and diverting to serve as a surrogate baby sitter, while perhaps just strange enough to appeal to hung-over adult hipsters.
*** By the autumn of 1991, Imelda Marcos was feeling sufficiently safe to go back to the Philippines with her three adult children.
At 19 of the 26 sites, the associated bacteria were above the level deemed sufficiently safe for swimming by the EU Bathing Water Directive.
He also said that NASA had not held detailed conversations with commercial companies about what would be necessary to make their rockets sufficiently safe for passengers.
But the Secret Service informed them that they would have to buy the entire street in order to make it sufficiently safe.
