What certificate must a pilot hold to flight test an aircraft that has been altered in a way that may affect flight characteristics?

A pilot must hold a specific certificate that authorizes them to operate an aircraft, particularly one that has undergone alterations affecting its flight characteristics. In the context of the correct choice, a private pilot certificate allows a pilot to fly an aircraft for personal use and not for compensation or hire.

When an aircraft is altered in a way that might impact its flight characteristics, the pilot’s level of training and understanding of those alterations become crucial. A private pilot certificate indicates that the pilot has received training and demonstrated proficiency in a specific set of skills, including understanding how modifications to aircraft can influence handling and performance.

While other certificates such as the commercial pilot and airline transport pilot certificates provide advanced privileges and typically necessitate a higher level of knowledge, they are not mandatory for a private pilot testing the aircraft itself after alterations as long as the flight operation remains within the personal, non-commercial realm.

It’s also significant that the role of a flight instructor certificate is primarily related to teaching and endorsing students rather than conducting independent flight tests after alterations, reaffirming that the private pilot’s foundational skills are indeed suitable for handling such a situation. Thus, the private pilot certificate is the appropriate answer in this scenario.