The federation of international pilots has issued alerts to its members about an ongoing risk to aircraft operations at Suvarnabhumi Airport due to soft ground conditions affecting taxiways, taxi lanes and aircraft stands.
The alerts were issued on Tuesday by the International Federation of Air Line Pilots' Associations (IFALPA) which represents over 100,000 pilots and flight engineers in almost 100 countries.
According to the warning, the soft ground conditions known in the aviation business as "soft spots", have been encountered and reported by flight crews and ground service providers at the airport since at least 2008.
The federation has advised airlines to alert flight crews to the existing hazards related to push back and taxi operations at the airport, and to apply appropriate operating procedures to mitigate the associated risks.
In addition, flight crews are encouraged to report all soft spot occurrences immediately to air traffic control so Airports of Thailand (AOT) personnel can be sent to investigate and assist as needed.
The federation said the AOT had issued an advisory about the pavement failure causes, saying the two main factors were deficiencies in the asphalt materials used in construction and the height of the water table under the airport.
These factors have resulted in soft spots and failures on heavily transited areas after about two years, well below the expected pavement lifespan of around seven years.
Short term mitigation measures implemented by the AOT have included temporary and semi-permanent pavement repairs and a 24 hour on-call team for quick repairs to minimise disruption to operations.
The federation said the AOT recently reported the contract to carry out permanent repairs was cancelled in the design phase, further delaying permanent repairs which are not expected to commence until at least late 2019.
AOT executives have yet to respond to the federation alert.