I am a high school graduate who loves aircraft designing and are aiming to get into universities that has aerospace engineering majors. However, I have heard people saying that since aircraft companies will keep their designers in the company until they retire, there is little oppurtunity to get into this industry. Is is true? If it is not, then where can I find more oppurtunities?
It is not necessary to have an Aerospace Engineering degree to get a foothold into the engineering side of aviation. Most of the major aircraft companies operate on a very long design cycle, and maintaining employees with specialty engineering disciplines is not cost effective. While there will likely always be SOME aerospace engineers employed by companies like Boeing, the majority of their engineers are Mechanical, Electrical, Industrial, Manufacturing, and Tooling engineers.
Mechanical engineering, in particular, would open you up to a much broader base of job opportunities all over, both in and out of the aerospace industries.
An invaluable resource for you as you look at your choices, is the Occupational Outlook Handbook, created by the US Bureau of Labor Statistics. In it is listed expected salaries, expected job growth opportunities, how competitive the field is, etc. For Aerospace engineering, for example, http://www.bls.gov/ooh/architecture-and-engineering/aerospace-engineers.htm indicates that the market is expected to decline by an average rate of 2% over the course of 2014-2024. This would indicate that Aerospace Engineers are not in high demand. However, Mechanical Engineers are expected to grow by an average of 5% in the same time period.