The fleet is evidently quite stretched at the moment, but it's not the first time there has appeared to be a run of reliability issues with the 747.

A good few years ago, there seemed to be regular problems with the fleet, including a memorable diversion to Kazakhstan due to a faulty fire warning in the cargo hold which required the despatch of a number of Airbus aircraft to rescue the passengers because a fully loaded 747 couldn't take off on the runway.