The Kansas City Hyatt Regency skywalk collapse on July 17, 198i during the Friday Tea Dance in the lobby killed 114 people due to a structural engineering error during construction, resulting in an infinite shear force applied to the concrete on the 4th floor walkway.
The Tacoma narrows bridge in Washington state collapsed when winds coming up the canyon excited a resonant frequency in the bridge leading to positive feedback and ever increasing oscillation amplitude.
I was changing a light fixture in my bathroom over the sink and all was going well until i began connecting the new fixture. The new fixture was larger than the old one and was blocking the light from the tub so I couldn't see the screws for the connections. I got down from the sink and instinctively flipped on the light switch. I climbed back up on the sink counter and started making the connections until I touch both wires. My wife heard 2 load bangs. The first was when I flew across the room and hit the shower wall, the second is when I dropped and hit the tub. I now always place tape over the switchs when I do electrical work at home.
Many, many years ago, when I worked for AST Research, I developed a motherboard ASIC that was basically a "garbage can" of the random logic. After the systems were in high-volume production for more than a year, there was a particular legal software title that would not "beep" correctly when some kind of event occurred, due to a subtle bug in my design. I've never held lawyers in high regard, so I thought it was kinda funny that I was able to jab a bunch them with my screw-up.
The wikipedia article to which the above link refers, says: "The engineers employed by Jack D. Gillum and Associates who had approved the final drawings were convicted by the Missouri Board of Architects, Professional Engineers, and Land Surveyors of gross negligence, misconduct and unprofessional conduct in the practice of engineering; they all lost their engineering licenses in the states of Missouri and Texas and their membership with ASCE."
Nothing beats the Mars mission with metric / US unit interchange - no loss of life, but lots of lost prestige, etc.
Always remember, as engineers, the world does revolve around us. We pick the coordinate system. (Stolen from somewhere, I forget where.)
"Indeed, introducing yourself as an engineer at a party likely won’t earn you the admiring ooh’s and ahh’s that, say, a fireman, or U.S. Navy Seal might get."
Hey Sylvie! Speak for yourself! I'd infinitely rather hear from an enthusiastic EE who is doing fun work, at a party, rather than a fireman. Sheesh.
Okay, so for EE disasters, e.g. the ones that would really make me pucker, are for instance a ship running aground, or colliding with another ship, because of a design fault in the control systems. Ditto, obviously, with airplanes.
Or cases of "friendly fire" caused by faulty identification hardware or software.
Take for example the disaster of that Air France flight over the Pacific, a couple of years ago. That was reportedly caused by sensor failure that gave the automatic controls the wrong instructions. Could a human pilot be trained to notice the problem? Most likely yes. But more to the point: could the control system be designed to accommodate that type of sensor failure?
These are the things that might keep EEs awake.
Let's not forget the fiasco of the original primary mirror on the Hubble Space Telescope, which was ground to the wrong shape and had to be replaced later by shuttle astronauts.
I have also heard rumors of a satellite that was launched, and during on-orbit checks, the command to power down was sent, but the craft never responded to a later command to power up again. When the same command sequence was tried on the Engineering Model back here on Earth, the same thing happened. Somebody apparently got over-zealous in deciding which circuits responded to the power down command.
But again, that's just a rumor I've heard, on and off over the years :)