When the passengers were about to board the flight, the pilot noticed a technical snag and informed the ATC and passengers were made to stay in the waiting hall.

Later in the early morning, the fault was rectified and the flight departed from Chennai at 2.47 am after a delay of three hours.

Sources said the Singapore airline officials had informed the pilots not to operate the aircraft even for a minor snag, after the London flight hit severe turbulence leaving a man dead and 23 of them injured on Tuesday.