The budget carrier's earnings for January-March was 40.9 million baht, down from 416.1 million baht recorded in the same period last year, the company said in its filing to the Stock Exchange of Thailand on Friday.
Nok Air, owned 39% by Thai Airways International, pointed to competition in the domestic air transport industry, from full-service airlines and low cost carriers (LCC), which grew more intense in the last quarter of 2013, coupled with the entry of a new LCC player - Thai Lion Air - as reasons for its fallen profits.
The civil unrest had decelerated the economy since the fourth quarter of 2013, and the private consumption index, prepared by the Bangkok of Thailand, had fallen by 2.5% in February 2014.
Passenger yield dropped 7.6% to 2.76 baht per seat/per kilometre from 2.99 baht in the same period of the previous year, while production unit costs rose marginally by 0.7% to 2.37 baht/seat/km against 2.35 baht a year ago.
The airline, which operates mostly on domestic routes, recorded an average airfare of 1,630 baht per passenger per sector, representing a 12.1% drop as intensified competition and prolonged political unrest placed pressure on airfares.
It carried 23.4% more passengers in the first quarter to record 1.77 million, and was able to fill 79.9% of available seats, but that was down from the 87.6% cabin factor registered previously.
The 9.5% depreciation of the baht to an average of 32.80 baht/US dollar also hit Nok Air's balance sheet as most of its major expenses are US dollar-linked.
Revenues were up 11% to 3.13 billion baht, lagging behind the 28.9% increase in expenses in the quarter.