From the recently published Stobart Group prospectus:
Actions taken by these significant customers such as reductions in operations or the use of the Group’s services could materially adversely affect the Group. Stobart Aviation is particularly exposed to this risk, as the operating contracts with the airlines operating at the Group’s airports do not commit either party to specific volumes of activity. There can therefore be no assurance as to the level of the Group’s future aeronautical revenue from any one or more airline operators. However, even where the Group does have contracts in place with its significant customers, if these customers suffer financial difficulties they may be unable to fulfil their contractual obligations.