You are rating an airport's debt. Compute its debt service cover, stress traffic down 30%, and say what else you would examine before assigning a rating.

Cover is 1.68x today and 0.82x if traffic falls 30%, because Rs 300 crore of fixed costs turn a 30% revenue fall into a 51% fall in cash for lenders. Cover reaches 1.0x after a 23.6% traffic fall. Beyond the numbers, a rating turns on the tariff framework, airline and traffic concentration, the catchment and competing airports, the capital spending plan and the reserves and covenants in the debt.

An airport is like a shopping mall attached to a toll gate. Every passenger pays a toll, the aeronautical charge, and spends in the shops, the other income; the building, security and staff cost much the same whether the terminal is full or half empty. Revenue moves with passengers while most costs do not, so an airport's cash for lenders is far more sensitive to traffic than its revenue is. That sensitivity is operating leverageThe degree to which profit moves more than revenue because a large share of costs is fixed., and it is the first number a rating analyst wants.

Revenue is 1.2 crore passengers times Rs 600, Rs 720 crore: Rs 420 crore aeronautical and Rs 300 crore other. Less Rs 300 crore of costs leaves Rs 420 crore, covering Rs 250 crore of debt service 1.68 times. With 30% fewer passengers, revenue is Rs 504 crore, cash is Rs 204 crore and cover is 0.82x: the airport cannot meet debt service from operations.

Work out the breakeven so the committee sees how far the cushion goes. Cover is 1.0x when revenue covers Rs 300 crore of costs plus Rs 250 crore of debt service, Rs 550 crore, which is about 91.7 lakh passengers. That is a traffic fall of 23.6%, which a pandemic, a home airline failing or a new competing airport could each deliver.

Group the rest into five questions. Who sets the price: the tariff framework decides whether aeronautical charges recover lost traffic later through a true-up, which can turn a traffic shock into a timing problem rather than a permanent loss. Who flies: an airport where one airline carries half the passengers carries that airline's credit risk. Why passengers come: the size and wealth of the catchment, the mix of business, leisure and transfer traffic, and competing airports nearby.

What must be built: expansion capital spending, how it is funded and whether it can be deferred. And what protects lenders: a debt service reserve account, covenants that lock up cash below a cover threshold, and debt maturities well inside the concession's remaining life. The closing view: on the numbers alone Suravel is thinly protected against a severe traffic shock, so its rating depends on how much the tariff framework and reserves cushion a year like the stress case. Confirm the current regulatory framework before relying on any true-up.