Bringing dormant planes out of storage and making them airworthy requires a significant amount of work. Pilots need to keep up their air miles in order to be able to fly, too.
With vaccine rollouts picking up pace and lockdown measures gradually being eased, airlines across Europe have started making preparations for a summer of increased demand.
Part of this work is focused on ensuring that the large proportion of planes that have been grounded for more than a year now are safe to fly.
But bringing these dormant planes out of storage and making them airworthy requires a significant amount of work.
Maintenance teams have to work round-the-clock to go through thorough procedures, making checks on every part of the plane and running tests on all the electronics, as well as ensuring that its safety equipment still works effectively.
The entire process can take at least 200 hours per aircraft, which Simon Michaux, a technical team leader at Brussels Airlines, says is a difficult task.
"The aircraft [in the hangar]... is one year on the ground in storage conditions and now we bring it inside the hangar to begin the return to operation procedure," Michaux told Euronews.
"It requires a lot of inspection and tasks need to be performed to make sure the aircraft is completely safe for operation. Every system... is checked. Every component of the aircraft is inspected, tested all in accordance with the manuals and that brings the aircraft back safe."
Unsurprisingly, flights have still not returned to their pre-pandemic levels, but things are slowly picking up pace.
According to Eurocontrol, at the end of April traffic flow over European skies was down by 62% compared to 2019, which is a marked improvement compared to the same time in 2020 when flights in Europe were down by around 99%.
But to get things up and running for the summer it isn't just the planes that need tending to.
Pilots need to keep up their air miles in order to be able to fly, which means that grounded pilots must have hours of theoretical and practical retraining, including in a flight simulator, designed to replicate conditions in a plane.
Jeremy Rooms, a deputy chief flight Instructor at Brussels Airlines, told Euronews that no pilot can fly unless they pass all the required tests.
"At regular times during their training, we take progress checks, we check them continuously to make sure they are up to the standard that is required that we are known for. So, we are not releasing any pilot on the line that is not fully capable of flying the aircraft in all safety that is our prime concern in any case - they are not going to be flying around," Rooms explained.
Learn more about