Flight 12 departed New York at 06:14 EST and Windsor Locks at 07:35 while on a cargo flight to Boston. The aircraft was on a runway 04R ILS approach when the nose suddenly pitched downward about 60 degrees, causing the aircraft to crash out of control, 7000 feet short of the runway threshold. Weather reported to the flight was: scattered clouds 400 feet, ceiling 700 feet overcast, visibility 1,5 miles in moderate sleet and fog. While descending through 3000 feet, the crew had requested a lower altitude because of moderate to heavy rime ice being encountered. PROBABLE CAUSE: “Loss of balancing forces on the horizontal surface of the empennage of the aircraft, due to ice accretion, causing the aircraft to pitch nose down at an altitude too low to effect recovery.”