His warning came in the wake of an AirAsia flight, on the Yogyakarta-Kualanamu route, nearly colliding with two balloons. One was only 10 metres away at 18,000 feet at 9.25am on Sunday, while another balloon was seen at 30,000 feet.

The balloons, powered by fire, can reportedly reach 35,000 feet. Generally, they measure 5 metres in diameter and 10 metres in height.

Apparently, two Citilink aircraft had the same experience as the AirAsia plane. The planes encountered big balloons at 9,000 feet and 17,000 feet respectively over Godean, Sleman, north of Surakarta.

The encounter by the three planes was also in Tempo.co in a report quoting Adi Sutjipto airbase spokesman, Major Sus Giyanto.

It appears that some revellers like to release big balloons, during Aidilfitri celebrations, to make wishes. It has been suggested that they were oblivious to the dangers posed to passing aircraft.