Complex sentence: The other doomed approach to warning the people was a leaflet drop, which didn't work for two reasons: first of all the Spinifex could not read the leaflets; and secondly they were wary and afraid of the planes.
Split into simpler sentences: The other doomed approach to warning the people was a leaflet drop. This actually didn't work for two reasons, first of all the Spinifex could not read the leaflets and secondly they were wary and afraid of the planes.