In recent years, wireless sensor networks (WSN) have been considered for various aeronautical applications to perform sensing, data processing and wireless transmission of information, without the need to add extra wiring. However, each node of these networks needs to be self-powered. Considering the critical drawbacks associated with the use of electrochemical energy sources such as narrow operating temperature range and limited lifetime, environmental energy capture allows an alternative solution for long-term, deploy and forget, WSN. In this context, thermoelectricity is a method of choice considering the implementation context. In this paper, we present hands-on experience related to on-going implementations of thermoelectric generators (TEG) in airliners. In a first part, we will explain the reasons justifying the choice of ambient energy capture to power WSN in an aircraft. Then, we will derive the general requirements applying to the functional use of TEG. Finally, in the last section, we will illustrate the above issues through practical implementations.