For months, the slumping global air travel has seen an unprecedented number off.

Jets parked at 1.2 3rd off the global fleet was stuck on the ground as they return to the skies.

Regulators are worried about everything from maintenance errors to rusty pilots.

The International Air Transport Association says this year has seen a sharp rise in the number off poor landings, with some resulting in crashes.

In May, 97 people were killed after Pakistan International Airlines plane crashed following an unstable approach to the airport.

Now, some insurers want to know if carriers are doing extra landing training for pilots who have bean off work for a long time.

European regulators say this year has also seen an alarming rise in incidents involving wrong airspeed or altitude readings.

In June, a whizz air pilot had to abandon takeoff after noticing the airspeed was indicating zero.

A ground examination found insects nesting inside a key sensor that after the plane had bean parked for 12 weeks.

Similar incidents have caused fatal crashes in the past, regulators say long periods out of service also raise worries, including contaminated fuel on drained batteries in emergency systems.

Now, airlines have developed training programs for rusty flyers.

But an industry association says pilots need to be honest about their abilities and confidence when they return to service lives could depend on it.