The Indian aviation industry which is an integral part of Indian transport network, plays a crucial role in connecting people, economies, and cultures. Indian aviation industry is highly competitive in nature. Hence, operational efficiency is of paramount importance to sustain profitability, enhance customer satisfaction, and to maintain a competitive edge. The primary objective of the current study is to explore the efficiency of 6 major airline companies operating in India covering both the full service and low-cost carriers using secondary data drawn from various sources from the financial year 2004-05 to 2018-19 and to analyze the impact of select environmental factors on the efficiency of Indian aviation companies through a regression model. The study initially determined how efficiently the operating cost and its components are utilized by each airline relative to its peers. Based on two inputs and two outputs, a non-parametric approach namely Data Envelopment Analysis (DEA) is used to estimate the Overall Technical Efficiency (OTE) of select airline companies during the period of study. The empirical estimates show that airlines are operating with OTE between 62.2% and 92.7%. It is observed that Jet Airways is the most efficient unit during the period of study. In the second stage of the study, a regression model is developed which proves that majority of the independent variables chosen for the study significantly predicts the OTE score of the select airline companies during the post-reform period.