Complex sentence: As the balloon is anchored to the ground with a metal cable, it only goes up and down, and was approved by the Civil Aviation Authority of Singapore to fly to a maximum height of 150 metres, or around 40 storeys.
Split into simpler sentences: As the balloon is anchored to the ground with a metal cable, it only ascends and descends vertically. Approval by the Civil Aviation Authority of Singapore is for a maximum altitude of 150 metres, or around 40 storeys.