One pilot stabbed another at the controls of an Emirati flight to Tel Aviv on Wednesday, causing it to suddenly plunge thousands of feet until passengers and the crew won a fight to regain control of the plane. By DAVID M. HALBFINGER, AARON BOXERMAN, NATAN ODENHEIMER, ADAM RASGON and THOMAS FULLER At first, it seemed like turbulence. Then like something worse than merely rough air on the flight Wednesday from Dubai, United Arab Emirates, to Tel Aviv, Israel. “The plane just started going up…