Database
db={collection:[{"to":"CHD","from":"BAN"},{"to":"CHD","from":"DEL"},{"to":"DEL","from":"BAN"},{"to":"CHD","from":"CHN"},{"to":"BAN","from":"CHD"}]}
Query
db.collection.aggregate({"$graphLookup":{"from":"collection","startWith":"$to","connectFromField":"to","connectToField":"from","as":"flights","maxDepth":0,"restrictSearchWithMatch":{$or:[{from:"BAN"},{to:"CHD"}]}}},{$match:{from:"BAN"}})