11.   Thick fog hampered visibility but the shelling, following two mortar-fired flares, silenced the rebels, a Central African military source said.

12.   Thick fog hampered visibility but the shell, following two mortar-fired flares, silenced the rebels, the source said.

13.   Officials said the crash site has low clouds that can hamper visibility from the air, making manoeuvering a big challenge.

14.   Snow was also hampering visibility in the area where the two ships sank.