ONGC retained the top position on the coveted list of 10 most profit-making PSUs, while Air India was the biggest loss-making state firm during 2010-11, according to a government survey. ONGC, the country's largest oil and gas producer, earned a net profit of Rs 18,924 crore during the fiscal. Air India, on the other hand, suffered losses of Rs 6,865 crore in the same period.