CatastropheCast.com is a disaster history show built around Walter, who approaches each catastrophe the way an investigator would, working from the evidence toward a cause. The subjects range widely. Air disasters form one strand, including the de Havilland Comet crashes of the 1950s and Japan Airlines Flight 123 on August 12, 1985. Structural failure is another, with the 2007 collapse of the I-35W bridge in Minneapolis. Beyond those sit the Spanish flu of 1918 and the earthquake, tsunami and nuclear crisis that struck Tohoku, Japan, on March 11, 2011. Walter likes to start with a question. Why are airplane windows round instead of square? How did Boeing and Airbus come to lead the jet business? The Comet story answers both. Along the way it deals with the problem of investigating a crash when most of the aircraft is missing, and with the examination of victims that ruled out a bomb. The bridge episode reaches back to the Federal Aid Road Act of 1918 and the numbered highway system of 1926. From there it settles on a 1977 decision to thicken the bridge's concrete and what that added weight meant across the bridge's full length and width. His habit of doing the arithmetic out loud is one of the show's quieter pleasures. For Flight 123, which was a listener request, Walter traces origins he places a decade before the crash and describes American investigators waiting days to reach the site. The flu episode puts the Spanish flu's hospitalization rate at three in four in some cases and sets it against the 2017-2018 season, which he recalls from his own work in hospitals. The Tohoku episode, which he flags as a longer special, turns to governance and preparedness. It compares Japan with places where weaker earthquakes have taken far more lives. The darkest material is in 'Podcast #38 - Suicide by Airplane', which gathers five incidents: crashes in Namibia, the Alps and a California hillside, a cargo plane that should have crashed, and a baggage handler who stole a plane. One case is rebuilt from a note that survived the impact and a recovered piece of the gun. Walter closes that episode by urging listeners to check on one another and to talk to someone if they need help. The production is informal. On air, Walter mentions a snoring dog, military aircraft over the house, and a ten-month absence he spent working multiple jobs. His closings point listeners to a 'what do you want to hear' link on the website, an email address and a Twitter handle. It suits someone who wants the mechanics of a disaster laid out plainly by a narrator who shows his working.