[{start_time:new Date("2020-05-18T06:15:00Z"),land_time:new Date("2020-05-18T07:30:00Z"),flight_time:1.25,passengers:"90",line_name:"WizzAir"},{start_time:new Date("2020-06-18T07:30:00Z"),land_time:new Date("2020-06-18T09:30:00Z"),flight_time:2,passengers:"111",line_name:"Lufthansa"},{start_time:new Date("2020-05-18T06:15:00Z"),land_time:new Date("2020-05-18T07:30:00Z"),flight_time:5.25,passengers:"90",line_name:"WizzAir"},{start_time:new Date("2020-06-18T07:30:00Z"),land_time:new Date("2020-06-18T09:30:00Z"),flight_time:8,passengers:"111",line_name:"Lufthansa"}]

db.collection.aggregate([{"$group":{_id:"$line_name",max_time:{$max:"$flight_time"},min_time:{$min:"$flight_time"}}}])