OKAY, LOTS OF PEOPLE LOVE THE RADIO-CONTROLLED HELICOPTER I’ve mentioned before. But here’s a caution from reader Mark Phillips: “Hi Glenn, I bought a couple of these last time you mentioned them. FYI, at my elevation (5300′) they can’t maintain altitude and drift down slowly even at max throttle. But they do make great cat toys.” Mountain-dwelling readers beware, especially if you lack cats.

UPDATE: Reader Ben Hammer emails: “I think reader Mark Phillips may have a battery issue. I live at 5367 feet. I have three of these helicopters and fly them indoors in my ‘A’ frame ceiling that is 20 feet high. I can go any where up there with ease. My first crash happened when I got to close to the ceiling and the vacuum produced by the blades sucked the helicopter to the ceiling, lost lift and came crashing to the ground! Oops. Flipped her upright and continued flying. What I have noticed it that each battery has different discharge characteristics, so each helicopter has a different amount of flight time. At the end of the discharge cycle there is not enough amperage left in the battery to lift the helicopter off the ground. Maybe he should get a new battery.”