Aviation industry is in none too happy a situation, paticularly in India, for some years. As pe recent news paper reports, things are disturbing indeed (Airline companies suffering losses, not able to pay fuel bills, have huge debt liabilities, not able to pay salaries, pilots leaving the companies, retrenchment of staff, mass cancellation of flights, companies not able to raise finances, lessors of aircraft asking to return their aircraft, etc.).
Any way, you may, inter alia, keep these things in mind.
Aircrafts can either be purchased, or taken on lease. There are many other costs also. Either way, it is a very costly business. Only a consultant can give an idea in this regard. Hope you have the required financial resources, or will be able to manage them.
The full picture will emerge only after the Consultants prepare a Techno-Economic Feasibility Report, which include a detailed Market Survey to determine present and future demand.
Procedure for starting a company in India can be seen at:
http://www.masterstrokeconsulting.com/procedure-establish-business-in-india.html
You may like to do some reading on aviation industry on the following sites, to enable you to take a decision in the matter:
http://www.yourbusinesspal.com/aviation_business_plans.html
http://in.search.yahoo.com/search;_ylt=A8pWB9pGurxOCigAhzbuPXRG?p=How+to+establish+an+aviation+company+in+India&fr2=sb-top&fr=yfp-t-704&meta=fl%3D0%26vc%3D&rd=adv