This paper provides a comprehensive analysis of the reliability of a tethered high-altitude telecommunications platform using risk tree analysis. It investigates the potential risks associated with utilizing the platform to deliver telecommunications coverage in a specific area. The study employs a well-known methodology to construct a risk tree, facilitating the calculation of pivotal characteristics such as occurrence time distribution of key risk events and their mean and variance as well as associated damage. Furthermore, the technique identifies the most critical risk paths and evaluates the sensitivity of risk characteristics to initial data, thus offering valuable insights for risk management and mitigation.