The mystery surrounding the vanished Malaysian airliner which vanished without trace with 239 aboard on Saturday was compounded by the discovery Tuesday by Malaysian military aircraft of possible fragments in the Strait of Malacca of the western peninsula. No further details were released. If the plane did indeed turn west, it would mean that for some unknown reason the pilot had turned around and veered off course instead of continuing from Kuala Lumpur to Beijing. No change of course was signaled to air control. This suggests that the distress signaling equipment in the cockpit had been disabled in some way. At least 40 ships and 34 aircraft are scouring the seas off Vietnam and Malaysia for the vanished airliner, plus 10 Chinese satellites, The CIA said Tuesday does not rule out terrorism.