Evolution has played almost as important a role in the development air aircraft as it has in the development of birds, although the timescales are very different, argued Boeing 787 Dreamliner chief test pilot Ricardo Traven at the 2019 Aeronautical Society of South Africa conference, in Pretoria, on Wednesday. (Traven had previously been chief test pilot for the Boeing F/A-18 Hornet fighter.)

"There are some moonshot designs, which I call revolutionary," he said. "Then there are evolutionary designs which have developed with time."

Revolutionary designs can be risky. "There are revolutionary things that can be done, that are successful," he observed. But, sooner or later, revolutionary technologies are going to copied, emulated or (if military) countered.

Like birds, aircraft (whether military or civil) exist in environments. "The environment can change rapidly for us," he pointed out. "What was great for one environment, can be a disadvantage in another."

Just as changing environments can result in bird species becoming extinct, so too can changing aviation environments make aircraft types or even categories (such as flying boats) extinct. Thus, the Lockheed SR-71 strategic reconnaissance aircraft, which could fly higher and faster than any other operational aircraft, became "extinct" (was withdrawn from service) because of the development of ever more effective spy satellites, and because it was too specialised to be adaptable to other missions.

On the other hand, the Boeing B-52 bomber and the Lockheed Martin C-130 Hercules transport were great examples of evolutionary aircraft designs. Both have been in service for decades, and both have been extensively modernised. 

The aviation environment will evolve, he stressed. It was a matter of evolve or perish. "Evolve rapidly. ... [with a]ircraft .... you have to have a design that allows rapid technology insertion."