Putri Prameshwari – Scores of flights to and from Sumatra had been delayed or cancelled as thick haze still covered parts of the island, forcing airports to suspend operations, airline officials said on Wednesday.

Some flights had to be delayed for more than six hours and several were called off due to the haze covering Jambi's Sultan Thaha Airport, Pekanbaru's Sultan Syarif Kasim Airport and Palembang's Sultan Mahmud Badaruddin Airport, said Hanna Simatupang, a spokeswoman for PT Sriwijaya Air.

"We ask for understanding from our passengers," Hanna said. "This is qualified as force majeure [a situation out of the operator's hands]." She said the delay for each flight was not too long, but it has severely affected subsequent departures.

"It has affected our second routes," she said, explaining that if a plane has a route linking Jakarta, Jambi and then Padang, the second flight from Jambi to Padang has been delayed.

Trisno Heryadi, corporate secretary of state airport operator PT Angkasa Pura II, said airports in Jambi, Palembang and Pekanbaru had been closed several times due to thick haze and limited visibility.

"Flights had to be cancelled because they could not even be diverted to the nearest airport since they were all covered by haze," Trisno said.

Edward Sirait, PT Lion Air's spokesman, said one of the airline's Boeings had been grounded in Jambi and could not fly back to Jakarta.

"There is nothing we can do but to wait for the haze to dissippate," Edward said.

Although the delays did not cause a significant breakdown of the airline's operations, Edward said Lion had suffered losses, but he gave no further details. "Our routes have been a mess," Edward said.

State flagship carrier PT Garuda Indonesia's corporate secretary, Pujobroto, said the haze created a domino effect to the airline's schedule. He said flights in Kalimantan had been disturbed besides those in Sumatra.

"We have to delay our morning flight from Palangkaraya to the afternoon," Pujobroto said.

He added that losses has not been calculated, but the delays had caused inconvenience and discomfort for passengers.

All three airlines allowed their passengers to refund their tickets or switch to the next available flight. Sriwijaya's Hanna said the arrangements were all the airline could do, since the disturbance to the flight schedules is caused by nature.

Bambang Ervan, a spokesman for the Transportation Ministry, said that airports had to be closed when the viewing distance dropped to less than 1,500 kilometers, depending on the size of the runway and aircraft.

Jambi's Sultan Thaha Airport, he said, had been closed and opened several times during the day due to the fluctuating range of visibility.