Air One Aviation (Delhi International) and other Indian start-up carriers may have to revise their respective plans to start international operations should the Indian government replace the existing 5/20 rule (an airline must have been in service for at least 5 years and operate at least 20 aircraft before applying for international traffic rights) with a credit-based scheme in which airlines earn the right to go external by first plying domestic routes.

In its latest proposal, the Indian Ministry of Civil Aviation says its "Domestic Flying Credits" (DFCs) scheme would allow carriers with a clean safety record and a minimum of five aircraft to serve international routes once they have accrued at least 2trillion DFCs.

"Operational data shows that an airline with 5 aircraft of the size of an Airbus A320 can operate about 150 crore ASKms (1.5trillion Available Seat Kilometers) in one year. With multiplier effect, an airline can do 200 crore (2trillion) DFCs in a year," a ministry presentation read.

Airlines earn one credit per passenger kilometer flown on Category-I routes while service to Category-II and Category-IIA airports would earn them three and five DFCs respectively. Service to unused airports will also earn them five DFCs.

The scheme may also allow for credits to be traded in which case scheduled airlines may be allowed to purchase 25-30% of DFCs.

In a bid to stimulate demand in its growing scheduled commuter airline sector, the ministry will encourage those with small aircraft to earn capacity deployed as DFCs and trade them with airlines planning new international flights.

Helicopter operators offering scheduled flights may also be granted a 5x DFC multiplier.

The ministry has also proposed amending the classification of Category I routes adding a further 14 to the existing 12. New cities are to include Goa Dabolim, Ahmedabad, Lucknow, Pune, Jaipur, Patna, Kochi International, and Chandigarh.

Category II and IIa airports may also be expanded from the current North-Eastern region, Jammu and Kashmir, Andaman & Nicobar Islands, and Lakshadweep definition to include the airports of Dehra Dun, Shimla, Kullu, and Dharamsala, in Uttrakhand and Himachal Pradesh.

Dedicated software will be used for calculating DFCs, whose calculation formula will apply to new airlines and in the allotting of new routes to existing airlines.