Conditions at Bangkok’s main international airport are raising concern among airline pilots once again.

The International Federation of Air Line Pilots Associations (IFALPA) issued a warning this week about soft ground conditions at Suvarnabhumi International Airport that can cause taxiways and aircraft parking areas to buckle and fail, according to the Associated Press.

The federation says the issues, including soft spots, have been causing problems since at least 2008. What’s more, this is not the first time the federation has issued such a warning. Four years ago, it made a similar statement.

IFALPA is a worldwide association of national pilots’ associations that was founded in 1948. Based in Quebec, Canada, it represents more than 100,000 pilots around the globe.

Airports of Thailand has said the pavement failures at the Bangkok facility are being caused by “deficiencies in the asphalt materials used in pavement construction and the height of the water table below the airport” the Associated Press reported.

That problem may be stemming from the fact that the airport was built on the site of a swamp.

A permanent solution to the problem is not expected to be put into place until late next year. In the meantime, however, a team has is on standby 24 hours a day to make needed interim repairs.

The soft spots and buckling are just the most recent criticism of Thailand’s aviation safety standards.

In 2015, the U.S. Federal Aviation Administration took the step of downgrading the country’s safety rating to a “category 2.”

That means Thailand’s civil aviation authority is deficient in one or more critical areas or that the country laws and regulations overseeing airlines are lacking in some way or do not meet international standards.

Thailand appears to be making at least some positive progress, however. Last October, the U.N.’s International Civil Aviation Organization removed the country from its list of places red-flagged for safety concerns.