Singapore Airlines (SIA) said on October 31 that its net profit soared 73.2 percent over the three months to September compared with a year ago due to buoyant travel demand.

But despite those fiscal second quarter figures, SIA, the first airline to commercially operate the Airbus A380 superjumbo, said slowing economic growth had cast a cloud over prospects.

Net profit totalled S$507.8 million, up from S$293.2 million a year ago, the company said in a statement to the stock exchange.

Revenue rose 9.9 percent to S$3.97 billion from S$3.61 billion in the same period last year.

"Passenger demand from both business and leisure markets remained buoyant in the second quarter, pushing passenger load factor to 81.6 percent," the airline said.

For the six months to September, net profit was S$931.9 million, up 7.32 percent over the same period the previous year, on revenue of S$7.59 billion, up 8.0 percent.

SIA, one of the world's most profitable airlines, on October 25 became the first airline in the world to commercially operate the double-decker A380 when it launched a flight to Sydney and back.

It won good reviews for its luxurious and more spacious interior that includes private cabins with full-length beds.

But the airline said the outlook was challenging and could affect revenues.

"While advanced bookings are holding up, slowing economic growth sparked by tight credit markets and increasing volatility in financial markets cast a cloud of uncertainty over the strong revenue environment," it said.

"On the cost side, the price of fuel remains a significant variable for the second half of the year," it said, referring to surging oil prices.

SIA raised fuel surcharges on October 24 to partially offset an increase in jet fuel prices.

On October 31, its shares rose 20 cents to close at S$19.60.