Database
[{"name":"name","dob":"","email":"","noOfpeopleClimbing":0,"details":"","status":"","timeIn":"","timeOut":"","timeFinal":"","history":[{"time":3,"date":"","climbers":"","names":""},{"time":2,"date":"","climbers":"","names":""},{"time":1,"date":"","climbers":"","names":""}]}]
Query
db.collection.aggregate([{"$match":{"name":"name"}},{"$project":{"total":{"$sum":"$history.time"}}}])