On the thirtieth anniversary of the crash, a memorial was dedicated overlooking the Tenerife airport, honoring those who perished there. The sculpture is in the shape of a helix. “A spiral staircase,” the builders describe it. “a symbol of infinity.” Maybe, but I’m disappointed that the more obvious physical symbolism is ignored: early model 747s, including both of those in the crash, were well known for the set of spiral stairs that connected their main and upper decks. In the minds of millions of international travelers, that stairway is something of a civil aviation icon. How evocative and poetically appropriate for the memorial — even if the artists weren’t thinking that way.