The ADF in Delhi will only be (in operation) for two to two and a half years, during which the shortfall can be met.
It is not UDF (user development fees), which is charged for 15 years, Civil Aviation Minister Praful Patel said.
His statement came as DIAL proposed to throw open the new domestic Terminal 1-D for operations from the second half of February. This terminal would be an interim arrangement till the new airport complex comes into being by 2010.
Patel said ADF, if approved, would be charged "till the time the project is completed" and the passenger "will not have to pay" after that. "It will be worked out reasonably. It cannot be an arbitrary figure, but has to be linked with the total cost."
The GMR-led consortium has reported an estimated shortfall of Rs 2,750 crore (Rs 27.50 billion). The ADF would be calculated on the basis of the difference between the earnings out of real estate development and the total shortfall.
The remaining amount is to be collected through ADF, which would be at different rates for domestic and international passengers.
While the DIAL has been pressing the government for allowing it to raise resources through ADF, the GVK-led Mumbai International Airport Ltd has not yet made such a demand.
The government has approved UDF of Rs 260 per domestic passenger flying out of the new Bengaluru airport from Friday. The charge is Rs 375 out of the new Hyderabad airport. International passengers at both the airports have to pay Rs 1,000 as UDF.
The IGI Airport is being upgraded by a consortium led by GMR Group. The modernisation work started in 2006.