THE Tatas, with their proposed Rs 1,475-crore market base, have been threatening to alter the rules of domestic aviation for some time now. And as the pro- and anti-Tata players go into hectic lobbying mode with the crucial Foreign Investment Promotion Board (FIPB) meeting coming up, an internal memo prepared by top Indian Airlines (IA) brass predicts that the Tatas' entry into the aviation sector "would result in rendering the domestic carrier (IA) sick and we would have a replay of the 1950 scenario when the industry had to be nationalised". "Competition is good for Indian Airlines and all other domestic airlines," says the memo. "What's not desirable is the excess capacity."