> higher altitude significantly increased the likelihood... This idea looks promise, but Denver is not high enough to make much difference from sea level. Fro

> higher altitude significantly increased the likelihood... This idea looks promise, but Denver is not high enough to make much difference from sea level. From experience, radiation detector shows significant raise from ~6000m, and at standard civilian airplane echelon 10k m, it buzzes continuously :) Most probably, errors caused from electric surges or from some local radiation anomaly, or from something like radar equipment. - I hear, in few places in world exists old buildings, even churches, build from stone with high content of natural radionuclides, so there radiation is significantly higher than standard level, but not too high to cause fast people death, so nobody care, but it departments found unexplained errors ;) Btw, stone with high content is widely distributed. After Chernobyl, we pay this much attention, and know, for this first care in Sweden in 1940s, all other countries after 1950s. And one person even said me, that near our city there are two mines, stone from one used for industrial buildings, for roads, and from other for homes.