Why do car alarms go off on Mt. Soledad?

To: Matmail:

I enjoy cruising up to Mt. Soledad to watch the tourists freak out when their car alarms sound after they've enjoyed the view and come back to their vehicles. I know to disengage my car alarm before ascending the mountain, but only by learning the hard way. What causes this phenomenon of car alarms giving out up there?

-- Greg Terry, Pacific Beach

By now I should know that the fun threshold out there in Aliceland is pretty low. But I didn't realize exactly how low until we packed a lunch and followed up on this query. So there we are sitting on the steps under the cross, waiting for some action -- buzzers, alarms, cursing, screaming -- thrilling tourist bedlam and a good laugh at their expense. About 20 minutes in, one guy got a little tooting sound out of his BMW when he turned the key in the door lock, but other than that -- nada.

The elves grow restless. Grandma Alice tries to distract them with deviled eggs and carrot sticks. Pa Alice is pissed because he can't get the Padre game on his old blue-plastic Emerson portable. Ma Alice tries to insinuate herself into a wedding party milling around on the lawn, hoping to find out where the reception is.

Suddenly bride, groom, and friends head for their parked cars. Must have been 20, 25 of them. Now we're cooking. Hours' worth of research telescoped into a few minutes. They exit the lot. No alarms. No shocked tourists. No laffs from the Alices.

So I can't even confirm that the phenomenon exists. But having gone this far, we've got to assume that enough elves with enough free time would eventually experience the thrill Greg describes. The explanation (if there is one) for the situation (if there is one) may lie in all those radio/TV/cell phone/pager transmitters a few hundred yards away from the lower parking lot, looming over all those expensive backyards.

More Static from Soledad

Hi, Matt:

People like myself who live in the shadow of Mt. Soledad get distortion on our cable channels 8 and 10 because we're too close to where the channels have huge antennas. We actually have to switch off cable and go to old-fashioned rabbit-ears to pick up those channels clearly. And as for your recent car alarm issue, we've had at least two incidents up there where we couldn't lock the car with the remote door lock button on our key ring. Down the hill, no problemo.

-- Ray Vance

I've checked with all my wave-wise sources, and they say there's a remote, very remote possibility that an errant blip from a particular transmitter might set off a tuned receiver like a car alarm. Let's make that a very, very, very remote possibility. More likely, when people go back to their cars, as you note, they push the button on their keychain transmitters and the radio interference field from the transmitter towers blocks the signal to the car's receiver. The alarm's not really turned off, though there's no way to know that.

But I figured this whole thing was a fool's errand to begin with. You don't have to go to Soledad to prove it. Just hang around any mall parking lot and you'll realize that half the population of the city can't get into their own cars without setting off their own car alarms anyway.