We have discussed the direct effect of the national lockdowns due to coronavirus weeks ago, a remarkable decline in global flights was observed.

The total flights globally were down by 62% in April, compared to 2019. Commercial air traffic was down by even more – 74% lower than last April!
In April 2020, Flightradar24 tracked an average of 69,586 total flights per day. The total number of flights tracked declined from mid-March to mid-April before recovering slightly in the second half of the month.
Commercial flights remained lower throughout the month of April. The April 2020 average was slightly above 29.000 flights daily, compared to near 112.000 flights daily in 2019. That is 74% less than normal!

Comparing the flights over Europe between Jan 5th afternoon and May 5th afternoon (2020) is beyond exceptional.