The Santa Barbara Airlines plane took off just before dusk from the city of Mérida en route to Simón Bolívar International Airport outside the capital city of Caracas. Noel Marquez, director of Venezuela's emergency management agency in Mérida, said the plane has failed to contact control towers. Civil Defense chief General Antonio Rivero told reporters that it is unknown whether or not the plane crashed or is simply missing.
The plane went missing at night
The context states the plane took off just before dusk, but we don't know if it went missing before dusk passed or not - so we don't know if it was night when it went missing. The system likely assumed that dusk had passed. 
( z1 miss :ARG1 ( z2 plane ) :time ( z3 date-entity :dxyperiod ( z4 night ) ) )