£500m downtime cost - British Airways
British Airways had an IT outage over the May Bank holiday in 2017. Over £500m was wiped off the market value BA's owner IAG.Read more
Commercial Appeal - FedEx IT outage in Memphis hub
FedEx experienced a temporary IT outage which affected aircraft launch operations overnight. They described the knock-on as "substantial disruptions" but explained that they "implemented contingency plans to minimize the impact".
Source: Commercial Appeal