There are a few common devices used to measure the temperature of different aircraft sections like the engine and cabin. An electrical resistance thermometer (ERT) is one such type of device, and it works on the principle of measuring resistance to a flow of electricity. ERTs are useful because they are highly sensitive, but they cannot withstand extreme temperatures. In contrast, thermocouples operate on a similar principle, but are able to work in a wider temperature range. As such, thermocouples are very often used in aircraft where temperatures can reach very high, like in the engine, as well as below freezing, like at high altitudes. Consequently, it is important to understand how these crucial components function on aircraft..

In the mid 1900s, aircraft cockpits were not equipped with electronic instrumentation and display systems. Apart from such advanced technology not existing, air transport operations did not necessitate modern systems like electronic flight displays. That being said, pilots often struggled to simultaneously manage hundreds of instruments during flight. These instruments would be displayed as gauges across the cockpit and were incredibly difficult to interpret during night flights because of the lack of illuminated components.