On 3 February 2013, an Airbus A340 crew in the cruise in equatorial latitudes at FL340 in IMC failed to use their weather radar properly and entered an area of ice crystal icing outside the prevailing icing envelope. A short period of unreliable airspeed indications on displays dependent on the left side pitot probes followed with a brief excursion above FL340 and reversion to Alternate Law. Excessive vibration on the left engine then began and a diversion was made. The engine remained in use and was subsequently found undamaged with the fault attributed to ice/water ingress due to seal failure.