Lucknow, Jan. 7 -- A Lucknow-bound Air India Express flight circled back to Delhi after it was denied landing permission despite making six rounds of the airport here on Tuesday, officials said. Flight IX-2171 was forced to return to Delhi due to extremely poor visibility. This marked the second instance in the last few days when the flight couldn't land at Lucknow due to dense fog. Last Friday, the flight was sent back to Delhi after it attempted to land, but couldn't, 17 times, officials said. Similarly, several flight operations continued to face disruptions at the Chaudhary Charan Singh International Airport here. Air India Express flight IX-1026 from Mumbai arrived nearly three hours late, while Flynas flight XY-333 from Riyadh was delayed by around two hours. Akasa Air's Mumbai-Lucknow flight QP-1524 reached the city over an hour late; and Air India Express flight IX-1058 from Delhi was also delayed by more than an hour. IndiGo flights were among the worst affected. Flight 6E-453 from Hyderabad was delayed by over three hours, Jaipur-Lucknow flight 6E-7482 by nearly four hours, Delhi-Lucknow flight 6E-6614 by two hours, and Indore-Lucknow flight 6E-7422 by more than three hours. Another Mumbai flight, IndiGo 6E-5088, arrived about an hour late. Similarly, departures on at least eight routes were also delayed. Air India Express flight IX-1027 to Mumbai left nearly two-and-a-half hours late, while Flynas flight XY-334 to Riyadh was delayed by over two hours. Akasa Air flight QP-1526 to Mumbai and Air India Express flight IX-1617 to Pune were also delayed by over an hour. IndiGo services faced prolonged delays, with flight 6E-758 to Delhi departing more than three hours late, 6E-7221 to Indore by three hours, 6E-6615 to Delhi by over two hours, and 6E-7027 to Jaipur by around three-and-a-half hours....