Imagine boarding a jet and heading for your seat, only to be told you’re needed in the cockpit to fly the plane.

Investing expert William Bernstein argued in a recent interview that what has happened in our workplace retirement system over the past 30 years is analogous. We’ve shifted from defined benefit pension plans managed by professional financial pilots to 401(k) plans controlled by passengers.

Once, employers made the contributions, investment pros handled the investments and the income part was simple: You retired, the checks started arriving and continued until you died. Now, you decide how much to invest, where to invest it and how to draw it down. In other words, you fuel the plane, you pilot the plane and you land it.

It's no surprise that many people, especially middle- and lower-income households, crash. The Federal Reserve’s latest Survey of Consumer Finances, released in September, found that ownership of retirement plans has fallen sharply in recent years, and that low-income households have almost no savings.

But even wealthier households seem to be failing retirement flight school.

Eighty percent of Americans with nest eggs of at least $100,000 got an “F” on a test about managing retirement savings put together recently by the American College of Financial Services. The college, which trains financial planners, asked over 1,000 60- to 75-year-olds about topics like safe retirement withdrawal rates, investment and longevity risk.

Seven in 10 had never heard of the "4 percent rule," which holds that you can safely withdraw that amount annually in retirement.

Very few understood the risk of investing in bonds. Only 39 percent knew that a bond's value falls when interest rates rise - a key risk for bondholders in this ultra-low-rate environment.

“We thought the grades would have been better, because there’s been so much talk about these subjects in the media lately," said David Littell, who directs a program focused on retirement income at the college. "We wanted to see if any of it is sinking in.”

Many 401(k) plans have added features in recent years that aim to put the plane back on autopilot: automatic enrollment, auto-escalation of contributions and target date funds that adjust your level of risk as retirement approaches.

But none of that seems to be moving the needle much. A survey of 401(k) plan sponsors released last month by Towers Watson, the employee benefit consulting firm, found rising levels of worry about employee retirement readiness. Just 12 percent of respondents say workers know how much they need for retirement; 20 percent said their employees are comfortable making investment decisions.