IndiGo will launch a direct daily flight between Delhi and Trivandrum (Thiruvananthapuram) on 7th January 2016, making it the longest domestic direct daily flight to be presently offered in India, with a block time of 3:15 hours.
6E 533 will fly DEL-TRV effective 7th January 2016, and 6E352 will fly TRV-DEL effective 8th January 2016.
No other operator offers direct flights between the two cities.
The flight will cover a great circle distance of 1201 nautical miles (NM) or 2,224 km.
Presently, the longest direct daily domestic flight in India is between Mumbai and Guwahati, operated only by IndiGo, with a great circle distance of 1,119 NM and a block time of 3:00 hrs from BOM-GAU, and 3:30hrs from GAU-BOM. The 30 minute difference is due to headwinds when flying from Guwahati to Mumbai, which serve as tailwinds when flying from Mumbai to Guwahati.
Thanks to Ameya: The longest domestic flight is Port Blair – Delhi (1,339 NM) operated by Air India regional on their CRJ 700s on Fridays and Sundays.