A Jet2 Boeing 737-800 en route from Alicante, Spain, to Glasgow, UK, declared a mid-air emergency over the English Channel earlier today. The situation unfolded as the flight initially progressed smoothly for the first two hours before encountering problems as it reached the airspace between northern France and southern England. The emergency was reported around 3:20 GMT when the flight crew transmitted a Squawk 7700 signal, indicating a general emergency.