A cargo jet chartered by the federal government to deliver badly needed personal protective equipment (PPE) from China was forced to leave the airport in Shanghai without the shipment on board.

The precious cargo of pandemic supplies wasn't lost or bought out by another country. Instead, the government says delays caused by a spike in cargo flights meant the delivery trucks couldn't get to the Canadian plane on time, forcing it to return to Canada without its load.

"This occurred due to on-the-ground congestion caused by a significant surge in cargo flights out of terminals at the Shanghai Airport. As a result, the intended cargo was unable to get to the plane before its required takeoff time," said Emily Harris, director of communications at Public Services and Procurement Canada.

The cargo still belongs to Canada; it's in a leased warehouse in Shanghai and the government says it will be delivered on a later flight. In addition to the empty federal plane, a cargo jet leased by an unidentified provincial government also flew back to Canada yesterday without its cargo for the same reason.

The missed deliveries are a setback for Canadian procurement efforts — but such supply interruptions don't mean the fragile PPE supply chain is completely broken.

Harris said four flights arrived from China over the weekend carrying medical supplies, including N95 and surgical masks, protective coveralls and one key component in reagents for novel coronavirus testing. Those planes also carried supplies ordered by the province of Quebec and the Red Cross.

Opposition Leader Andrew Scheer and Prime Minister Justin Trudeau spoke in the House of Commons on Monday 2:23

Conservative Leader Andrew Scheer raised the issue of empty flights in the House of Commons on Monday. Scheer asked Prime Minister Justin Trudeau twice about reports that three chartered planes sent by Canada to China to pick up medical equipment returned to the country empty Sunday.

Trudeau did not deny the report, saying Canada, like other countries, has struggled to get orders filled at a time when the entire world is trying to buy the same pandemic supplies.

This morning, Trudeau clarified the details during his daily media conference just outside Rideau Cottage. He said two planes came back empty, not three, and that one was chartered by a provincial government.

Prime Minister Justin Trudeau spoke to reporters on Tuesday 1:45

Trudeau cited severe restrictions on the ground in China on how long a plane can stay at the airport before having to take off — whether it's full or not — as the reason the plane returned empty.

"Supply lines and truck shipments to the airports are difficult and interrupted by checkpoints and quarantine measures," Trudeau said.

"For the most part, we've been able to navigate through those and ensure that Canada has received the equipment that it needs, but these two airplanes were forced to take off empty."

Canada has taken steps to build its own supply network for PPE to avoid some of the chaos affecting the global supply chains. Canada's Ambassador to China Dominic Barton redeployed much of the staff at Canada's embassy, consulates and trade offices all over China to focus on buying medical supplies for Canada.

The government also has hired two companies — Deloitte Canada and Bolloré Logistics — to identify reliable PPE manufacturers and to help with transportation, storage and customs clearances.

These measures have allowed the federal government to deliver millions of masks and gloves to front line workers and to help bolster provincial procurement efforts.

But the supply network is incredibly fragile and Harris said the setback with the empty planes shows the system needs some tweaks.

"We are closely monitoring this issue and continue to work closely with officials in China, including Ambassador Barton and other diplomatic staff, to navigate the current, complex supply chain environment," she said. "Steps are being taken to ensure that this does not occur moving forward."