I'm 46. I hear a lot about older engineers "not keeping up", "not being as technical", and "not learning new stuff". You know, I'm sure there are some...but not all. Some of us are still out there MAKING the technical bleeding edge in one field or another. Another instance of a too-broad brush.
The industry used to demand "well-rounded" engineers. If I have a family, I'd like to spend time with them (not working). I may have interests (that are not work). As a human, I need to rest/relax once in awhile. Younger folks, especially unmarried ones, tend to abuse our bodies and work more than we should (I can say this because I used to be one :-) As engineers mature, they often find a balance and work fewer overtime hours (still more than many professions, though), but this is usually counted AGAINST them - and shows up as age discrimination, as BobsUrUncle noted above.
If the U.S. economy ever gets around to improving, then demographics will win out as the superior talents and skills of the older engineers will be recognized as the competitive advantage it is.
This notion that older engineers are "past their prime" is utter nonsense. Most of us do take the time to keep up to date. We read, learn new skills and build on our vast experience to give us an edge that cannot even be approached by the younger generation.
I will be interested in the survey results. I am probably the exception in that I have good job security at 74. I am not a burden to the company's health care because I have medicare. I am looking forward to working until I am as old as my supervisor. He is 90. He also owns the company.
Yes, age discrimation is a big problem and is a cause of high unemployment in engineering. One factor is cost associated with benefits for 'older' employees including sick leave and health insurance. The other is the belief that their best years are behind them and that they are not as sharp as younger employees, nor willing to put in free overtime like younger (more gullible) employees.