The discipline of Flight Test Engineering has existed since at least 1903, but when did engineers identify their work, distinguish their work from other disciplines, under terms that would mark it as Flight Test Engineering?
This may take the form of someone who first used the term flight test engineer or flight test engineering.
Google demonstrates a history of the terms:
NATO describes the history of its flight test organization this way:
Soon after its founding in 1952, the Advisory Group for Aerospace Research and Development (AGARD) recognized the need for a comprehensive publication on flight test techniques and the associated instrumentation. Under the direction of the Flight Test Panel (now the Flight Vehicle Integration Panel) a Flight Test Manual was published in the years 1954 to 1956. This original Manual was prepared as four volumes: 1. Performance, 2. Stability and Control, 3. Instrumentation Catalog, and 4. Instrumentation Systems. As a result of the advances in the field of flight test instrumentation, the Flight Test Instrumentation Group was formed in 1968 to update Volumes 3 and 4 of the Flight Test Manual by publication of the Flight Test Instrumentation Series, AGARDograph 160. In its published volumes AGARDograph 160 has covered recent developments in flight test instrumentation.