"Hello everyone, this is the captain speaking. This is normally the point where I tell you about the weather in [destination], and that we've reached our cruis

"Hello everyone, this is the captain speaking. This is normally the point where I tell you about the weather in [destination], and that we've reached our cruising altitude. Unfortunately, we haven't reached our cruising altitude, so I won't tell you about the weather. We have a serious problem with this aircraft, and we're going to return to [origin]. We must first reduce our weight, so those of you at the rear will soon see a white spray from the wings as we dump some fuel. That should take about 20 minutes, and we'll then begin our descent. Please listen to the instructions from the cabin crew, who will prepare you for the landing." "Landing", in this case, meant the heaviest landing I've ever experienced, followed by the strongest braking, and fire engines surrounding the plane and spraying the undercarriage. Fortunately, this was a precaution, and we didn't have to evacuate the plane. The crew stayed with the passengers until everything was sorted out (luggage, hotels etc), and I found myself in conversation with an elderly couple from row 1, the first officer and the purser. The woman passenger said she had seen how calm the purser was, and was reassured that all was fine. The purser replied "ma'am, I'm trained to stay calm. This is the worst incident of my career, and I'm due to retire next year." The first officer explained that the primary hydraulics had failed. The hydraulic fluid is flammable, and could be leaking somewhere hot (or due to be hot, i.e. the wheels). They pressed a button which opened a valve and flushed the hydraulic pipes with inert gas, but it wasn't possible to know if that removed any/enough remaining fluid -- hence the fire engines spraying the plane when it landed.