Iran's national air carrier has signed an agreement to buy 20 new passenger airplanes with an option for 20 more from ATR one week after the airline signed a deal to buy 118 aircraft from Airbus. The company announced the deal was signed with Iran Air and includes a firm order for 20 ATR 72-600. The Tehran-based private Donya-e Eghtesad daily says the deal is worth $1.089 billion.