Mumbai: Harmonization of operating manuals across all Tata group airlines has been completed ahead of the Vistara-Air India merger and amalgamation of AIX Connect with Air India Express, it said in a statement on Monday.

Currently, the steel-to-software conglomerate wholly owns three airlines – Air India, Air India Express and AIX Connect (formerly AirAsia India) – while it has a 51 per cent stake in Vistara.

Singapore Airlines holds the remaining 49 percent stake in Vistara.

After completion of the harmonization of operating manuals, Air India said there will be two separate manuals, one for full-service carrier Air India and the other for low-cost cost-carrier Air India Express.

Before this, all four airlines had separate operating manuals.

Air India said that over the last 18 months, a team of more than 100 members has worked to adopt best practices and adopt common operating procedures.

"This is an important milestone in the merger of the Tata group of airlines," said Campbell Wilson, managing director and chief executive officer of Air India.

The statement said Air India and the group companies are now undertaking the necessary crew training to implement the harmonized procedures.