Singapore Airlines is investigating how one of its jets suffered a power loss in both engines, falling 13,000 feet (3,962 meters) before regaining altitude en route from Singapore to Shanghai.

The airline says the Airbus A330-300 lost power after hitting bad weather 3 1/2 hours into the flight Saturday. Power was restored after "the pilots followed operational procedures to restore normal operation of the engines," according to the airline.

FlightRadar24.com and the Aviation Herald say the jet dropped to 26,000 feet (7,925 meters) before power was restored, and climbed back to 31,200 feet (9,510 meters) before landing in Shanghai about 1 hour, 40 minutes later.

Singapore Airlines said no "anomalies" were detected in either of the engines. Aviation Herald said the plane returned to Singapore after a two-hour delay.