What's happening to all those grounded jets?

Row, upon row, upon row, of jet planes just sitting around.

Times are tough right now for passenger airlines.

But the tricky business of storing all those grounded planes is booming.

So is working out what to do with those jets that will never make it back into service.

Tarbes is an airport close to France's border with Spain, in the beautiful shadow of the Pyrenees mountains, and it's a parking lot.

Two-thirds of the world's fleet was grounded in the past few months.

One company, called TARMAC Aerosave, has more than 200 aircraft on its sites - beating its previous record of 150.

CEO Patrick Lecer says for now it's mainly for storage.

"All the maintenance and dismantling activities have been put to hold, if you want. We're 99 percent concentrated on storage, so we have a lot more requests for storage, but a lot less requests for maintenance."

Most new arrivals go in what's called "active" parking, ready to fly at short notice.

Hydraulics are drained, moving parts get a coat of grease and fuel tanks are left at ten percent. That's to keep its seals from drying out.

After three months, aircraft have to either leave or go into longer-term storage.

That means protecting cabins and engines with bags of silica gel to protect against humidity.

A jet like the A380 needs 100 kilograms of the stuff.

But as things return to normal, not all jets will return to the skies.

Airlines are facing new existential threats, as governments cut financial support, bills fall due and passengers stay away.

Patrick Lecer, the CEO, sees growth within the original thinking behind his company: Recycling older jets for scrap, and using the parts in newer less polluting aircraft.

"The new aircrafts, they burn 25 percent less fuel, so it's a lot less carbon dioxide, and nitrous oxide, so there will be a trend, we all believe there will be a trend in dismantling and recycling the older aircrafts, which are more polluting, yes. // (We have to) find a way to recycle this composite carbon structure (used by new planes). Today, there is no efficient way to recycle it, so we are working with all these companies. This will be, in my opinion, this will be the key element in the future, to be able to recycle at the level that we recycle today, the aircraft to come."

Current industry predictions are that it will take three to five years for air traffic to return to normal.

Until then, the fate for many jets will be either long term storage -- or the breaker's yard.