The inside of an Amazon fulfillment center in Robbinsville, New Jersey on December 2, 2019. REUTERS/Lucas Jackson/File Photo Amazon has massively scaled up its workforce and logistics network to respond to the surge in online shopping during the holiday season due to the pandemic. The e-commerce giant has hired more than 400,000 employees, grown its delivery fleet to include a total of 80 planes and 50,000 delivery trucks, and has expanded its warehouse space by more than 50%. But Amazon still faces some major challenges, including high worker turnover rates, capacity issues, and unknowns surrounding COVID-19. Visit Business Insider's homepage for more stories. As Black Friday kicks off the holiday shopping season in the US, few companies have had to prepare quite like e-commerce and logistics giant Amazon.An Amazon spokesperson told Business Insider the company is confident in the capacity it has added and its delivery speeds while still being able to keep employees safe.But the unprecedented nature of the COVID-19 pandemic and its impact on online shopping means even with those preparations, Amazon's logistics empire will be in for one of its toughest challenges yet.Amazon has built one of the world's largest logistics networks, currently operating 1,466 facilities globally that span more than 326 million square feet, according to logistics consulting firm MWPVL.