Back in the late ’80s, global airlines scrambled to place orders for Boeing’s (BA) 747-400 widebody, then the industry’s most coveted aircraft for its sheer size, high-tech cockpit, and creature comforts. Now, ten-year-old passenger 747-400s are worth a record-low $36 million, about 10 percent less than similarly aged planes last year, according to London-based aviation consultancy Ascend, as carriers seek more fuel-efficient models. There’s even little interest in converting the passenger jets into air freighters because of a slump in air cargo demand.