Of 7,377 Avro Lancasters built, only two can still fly

The Avro Lancaster was built in huge numbers: 7,377 of the heavy bombers came off the lines. Today just two remain airworthy, according to a post from an aviation-history account. That is roughly one in every 3,700 aircraft, and it explains why the sight or sound of one in the air still draws crowds. It is also a quiet lesson in how little of mass-produced machinery survives, even when it was once built in the thousands.