On the contrary, there are many indications in his teaching that he knew all about calamity. Thus, although God clothes the grass of the field , it is still cut down and burnt. God protects even sparrows, which are so common and are of such minimal value that two are sold for a farthing and five for two farthings, one being thrown in for luck. But sparrows do fall to the ground and get killed. His promise was not that they should not fall, but that this would not happen without God's knowledge and consent.
People fall too, and aeroplanes.
Christ's words cannot be taken as a promise that the law of gravity will be suspended on their behalf, but again that God knows about accidents and allows them. This was the assurance which fortified Dr. Helmut Thieliche while he preach a course of sermons on the Sermon on the Mount in St. He often alluded to the scream of the air-raid sirens, alerting people to yet more devastation and death from allied bombs. Against that background the command to look at the birds and lilies might well have sounded hollow. In other words, it is reasonable to trust in our heavenly Father's love, even in times of grievous trouble, because we have been privileged to see it revealed in Christ and his cross.