IndiGo took delivery of its third new A-320 aircraft on September 28, and will add the fourth one this week.
The fourth aircraft will be used to add three destinations - Mumbai, Nagpur and Vadodara - to the network, Bruce Ashby, president and CEO of IndiGo, said.
The airline hopes to carry 4,75,000 passengers with six airplanes by the end of calendar year 2006, Ashby added.
Nine more aircraft will be added in 2007, and IndiGo's fleet would comprise 15 aircrafts by December 2007.