Professional Engineer license is required for people who aspire to go in as officially approved engineer. The design specification is done by self-employed people or working in small business. General aerospace engineers work for government or for big companies and hence few people are not very keen on becoming PE’s. To become a PE one has to pass an exam on fundamentals of engineering which takes alot of hours to gruel and work under a licensed PE for about four years. In addition, they have to grow through a principle and practice of engineering exam, which requires about 8 hours.