BRUSSELS — Summer getaways are at risk of disruption as airlines across Europe brace for a jet fuel crunch that threatens peak travel season. There's no crisis yet, but concern is mounting that if Iran's effective closure of the Strait of Hormuz continues, airlines will resort to widespread route cuts, cancellations and fare hikes. “May is going to be very difficult because you do not have the capability to replace the lost [jet fuel] volumes from the Strait of Hormuz,” said George Shaw, senior