A senior executive for the world's leading aviation trade association says Severe Acute Respiratory Syndrome poses what he calls "a crisis of unprecedented magnitude" for Asia's airline industry.

International Air Transport Association Regional Director Andrew Drysdale told an international conference in the Philippines Wednesday that Severe Acute Respiratory Respiratory Syndrome, is the worst crisis in the history of the Asia-Pacific aviation industry.

He says SARS dwarfs the recent Iraq war and the terrorist attacks of September 11 combined in terms of the trouble it has caused the region's airline industry.

IATA says losses to the industry stand at $10 billion this year, and will likely increase until SARS is brought under control. The group says some Asian airlines have only 15 to 20 percent of their usual number of passengers for this time of year, even after cutting flights from their schedules.

A number of regional carriers, like Hong Kong-based Cathay Pacific, are asking employees to take four or more weeks of unpaid leave to help offset losses.

Despite the gloom, IATA says no regional carrier appears to be in immediate danger of going under.

Health experts say SARS is the first global epidemic to spread through air travel. But aviation officials say they are dealing with a problem of perception rather than one of public health. They say the risk of contagion while onboard a flight is very low.

IATA says there have been only five likely cases of SARS infection on an airplane during a period when the industry transported about 250 million passengers.

Many of Asia's international airports are screening inbound and outbound passengers. Passengers are given a temperature check and answer basic health questions to determine if they are infected. Aviation officials say since those measures were implemented, there have been no known cases of in-flight contagion.

IATA says the World Health Organization needs to standardize these measures in airports across Asia and the world. Aviation leaders in many Asian nations want a single protocol that unifies the efforts of aviation, health, quarantine and immigration departments.

Aviation officials say that despite screening and other methods, the airlines are in for a turbulent ride in coming months. They say carriers in hard-hit places like Hong Kong and Taipei will need at least three months, perhaps even a year, before their business recovers.