United To Alert Customers When Their Flights Are Getting Full

United Airlines will notify travelers if their flights are near full capacity, allowing them to rebook or cancel for a travel credit. This policy, effective next week, aims to address concerns about social distancing on flights. It follows a viral tweet about crowded flights and will last until at least June 30th. United will contact customers 24 hours before their flight and allow changes at the gate if over 70% of passengers have checked in. Despite reduced flights due to the pandemic, some flights are unexpectedly full. The International Air Transport Association does not support leaving middle seats empty, citing face masks as sufficient protection.

What factors have led to United Airlines having flights that are less than half full?

What does the International Air Transport Association say about leaving middle seats empty?