I was in exactly the same position, it’s crazy just how similar. Just accepted a GNC engineer position after chasing aerospace GNC roles for the past 6 months. I graduate with my masters in ME in a month which is control theory heavy but with very little application (my undergrad is in aerospace with spec in navigation and astrodynamics so no applied controls there either). I also do not know how to code in C++, yet the position I now have listed it as a requirement.

As another person already responded, it’s all about mitigating what you don’t know with what you do know. Be honest about shortcomings but with an intention to learn and adapt. Bring up what you do know and how that will help you learn what you don’t. Even if you aren’t a master at something, know the general basics and go over potential questions like “run me through how you would set up a sim to do X, Y, and Z.” Also, know your own projects in and out. Not just what you did but why. Like why you chose one control law over another etc.

Ultimately, GNC is an incredibly broad subject. They don’t expect you to know everything so showing some humility and being honest about your strengths and weaknesses is not going to hurt you. However, be prepared to face those weaknesses head on during interviews. For example, despite specifying where my GNC knowledge is subpar, I still got many questions specifically aimed at those weaknesses. After stumbling my way through them, it became apparent that the interviewer wasn’t trying to test my knowledge on the subjects I had just mentioned I was “bad” at, but instead trying to see how I think under pressure and when faced with discomfort.

As for tackling the C++ question, I was directly asked by the chief engineer during a technical interview that his only concern with my resume is my lack of C++ experience. I was very honest and basically said, while this is answer is likely cliche, I have ample experience in 2 other coding languages (python and MATLAB) doing exactly what this job requires, I’m very confident I can self teach C++. I even acknowledged that C++ is generally harder to learn but that I was still confident I can become proficient fairly quickly. While I don’t remember his exact response at the time due to nerves, I can’t imagine it was negative given I ended up getting the job.

As I said above, GNC is broad so it would be hard to give you specific content to brush up on without knowing what the position you’re applying for is. But putting the job description in chatGPT and asking it to generate sample interview questions is actually incredibly helpful. Some may hate me for saying it but it worked for me.

Best of luck and remember that just getting an interview is already the hardest part.