With a significant increase in air travel across many developing countries, assessing flight schedules and delays and investigating their causes for flights between cities with single runways is essential. This study investigates delays and reliability across 17 air routes connecting 6 saturated airport cities in India. It examines the delays at the origin, en route, and landing observing a lack of timely departure from the source. There is a huge variation in delay at the airports during take-off/landing. Air traffic at the destination is observed to weakly affect delay. This paper provides insights into the logistics in the aircraft sector since the results will help assess the scheduled slack effectiveness and offer operational strategies such as better crew and fleet management, to optimize scheduling and mitigate delays despite single-runway constraints and increasing air traffic.