There are a number of reasons why people perceive air travel as more dangerous than it really is.

1) For older people, it is within their living memory when air travel was much more dangerous than it is today, and even more so for their parents who shaped their thinking and behavior.

2) Air travel is outside your personal span of control. Other than choosing an airline with a better safety record (pretty much irrelevant in the developed world), there is little one can do to improve your odds of avoiding an accident. When people drive, they perceive themselves as affecting the odds in their favor positively. In reality, they may not be, but it is perception that matter.

3) The unusual is always considered riskier than the commonplace. Almost everyone rides in a car more than they ride in a plane.

4) People perceive car accidents as survivable. They don't perceive air crashes in the same way.