Cirrus Real Time Processing Systems Pty Ltd v Jet Aviation Australia Pty Ltd

The appeal in *Cirrus Real Time Processing Systems Pty Ltd v Jet Aviation Australia Pty Ltd* concerned the proper construction of a contract for aviation services. The primary dispute revolved around the interpretation of a price adjustment mechanism within the contract, specifically the meaning of the "Base Date Index Value" in circumstances where that composite term was not explicitly defined, although the "Base Date" itself was. The case was heard in the Court of Appeal of New South Wales.

The central legal issue before the Court of Appeal was how to determine the "Base Date Index Value" for the purpose of calculating price adjustments under the contract. This required the court to consider the contractual purpose, the commercial implications of different interpretations, and how to construe a varied contract where a key term within a defined mechanism was not itself defined.

The Court of Appeal allowed the appeal, finding that the "Base Date Index Value" should be interpreted as the value of the relevant index for the quarter containing 1 January 2018. The court reasoned that this interpretation best reflected the commercial realities and the overall purpose of the price adjustment clause. Consequently, the court set aside the orders of the first instance judge and made declarations regarding the proper construction of the contract, ordering the respondent to pay the appellant outstanding amounts and accrued interest. The respondent was also ordered to pay the appellant's costs of the appeal, with no order as to costs at first instance.