Like a hole in the head

By A.B.

ON FRIDAY a Boeing 737-300 operated by Southwest Airlines had to make an emergency landing at a military airport soon after take-off from Phoenix. A hole had opened up in the fuselage skin, leading to the rapid depressurisation of the cabin. The National Transportation Safety Board (NTSB), which is leading the investigation into the incident, will analyse the ruptured segment in due course to try to understand the reasons for the rupture, but said on Sunday that it had already "found evidence of additional cracks" on other portions of the joint along the fuselage.

Quite rightly, no aspersions are being cast about the general safety of Boeing 737s. After all, they are the only plane that Southwest flies and the company has suffered just one hull-loss in its entire operating history. It currently has 548 737s: 79 of these have take-off and landing cycles comparable to the stricken craft's and are being tested for signs of the skin fatigue that helped create the hole in Flight 812. By Sunday night "crack indications" (in NTSB parlance) had been found in three planes, which have been taken out of service for further testing and possible repairs.