What is Flight Test?

20 May 2022

What is flight test? As a concept, flight test sounds exciting – it implies having "The Right Stuff” because “failure is not an option.” It suggests first flights of prototype vehicles, with orange wiring and experimental components.  Boldly pushing to the edge of the envelope… and a maybe a bit beyond.  Even the Marvel superhero movies feature test pilots! However, setting aside pop culture references, when we think of flight test our first image is often of a test pilot or flight test engineer. We associate flight test with famous names in aerospace, like Bob Hoover, Jack Ridley, Chuck Yeager, Gene Kranz, or Burt Rutan. Certainly, these are celebrity names for aerospace enthusiasts, with photos on display in the Smithsonian. But flight test is more than a job title or a diploma – there is a perspective and methodology that can be learned and practiced.

Aerospace is a trending concept today, as we seem to be on the brink of a renaissance in flight. We see autonomous vehicles, commercial space, electric propulsion, urban air mobility, and hypersonic business jets splashed across the cover of not just Aviation Week but Time magazine. Practically speaking, though, how does one go about flight testing a new (or modified) vehicle? Do we just kick the tires, “send it”, and see what happens? How can development teams balance their competing priorities for accelerated development with risk controls, while successfully innovating next-generation capabilities?

Flight test concepts are applicable not only to conventional aircraft designs, but equally also to emerging and breakthrough development projects. The father of modern aviation, Wilbur Wright, stated, “In flying I have learned that carelessness and overconfidence are usually far more dangerous than deliberately accepted risks.” It is not only possible, but necessary, to use a systematic and risk-controlled methodology to expand and explore the flight envelope of a system. Keep in mind that risk takes many forms – not just safety. Employing proven strategies for flight test and risk management improves program effectiveness and efficiency.

The fundamental perspective for flight test is to answer questions while controlling risk. Flight test is not a zero risk endeavor, nor should it be. Risk can have many dimensions, not just safety. The key is to target the right levels of risk, appropriate to answering the engineering questions. In order to get meaningful answers, it’s important to ask the right questions, the right way – and know when you’ve got your answer. Much of the value of flight test is being able to properly frame these questions and approach the questions in a rationally planned sequence. Test can be “verification” (which is to ask the question, did we build it right?) and/or “validation” (which asks the question, did we build the right thing?). The desired outcome of test is understanding the vehicle/system behavior, with the goal to enable future care-free operations free of unexpected consequences or hidden “cliffs”.

Flight test is a methodical approach to building confidence in a system with awareness and defined acceptance of controlled risks. Flight test is not a singular event or phase just prior to customer delivery, it should be a spectrum of activities throughout the development process. Flight test is not a cost, but an investment. Most importantly, flight test is a team sport that can be learned and developed. The next post will describe the two foundational concepts for professional flight test.