Mongodb query not able to sort by field inside array

I have the following data in a mongodb collection:

{ 
    "base" : "XYZ", 
    "zone" : "ABC WEST", 
    "employees" : [
        {
            "fullname" : "RONALD GONZALEZ", 
            "status" : "approved", 
            "days" : 1.0
        }, 
        {
            "fullname" : "RODRIGO GONZALEZ", 
            "status" : "approved", 
            "days" : 4.0
        }, 
        {
            "fullname" : "GUILLERMO BARROS", 
            "status" : "approved", 
            "days" : 4.0
        }
    ]
}
{ 
    "base" : "ABC", 
    "zone" : "ABC CENTER", 
    "employees" : [
        {
            "fullname" : "MARTA DIAZ CABELLO", 
            "status" : "approved", 
            "days" : 2.0
        }, 
        { 
            "fullname" : "ALEXIS MARAMBIO",
            "status" : "approved", 
            "days" : 2.0
        }
    ]
}
{ 
    "base" : "ABC", 
    "zona" : "ABC AU", 
    "employees" : [
        {
            "fullname" : "JOSE MELLADO", 
            "status" : "approved", 
            "days" : 1.0
        }, 
        {
            "fullname" : "MARSAL MELLADO", 
            "status" : "approved", 
            "days" : 4.0
        }, 
        {
            "fullname" : "ALEJANDRO KOBBRT", 
            "status" : "approved", 
            "days" : 5.0
        }, 
        {
            "fullname" : "MANUEL SOLIS", 
            "status" : "approved", 
            "days" : 4.0
        }
    ]
}

I need sort these documents using something like (base asc, zone asc, inside employees list order by fullname asc):

{ base: 1,  zone:  1, "employees.fullname" : 1 }

But with these params only can sort by base-zone, inside the employess array it's not able to sort by the name field:

I tried to get this result:

{ 
    "_id" : ObjectId("5f5e3ab682947e5e20fa4084"), 
    "base" : "ABC", 
    "zone" : "ABC AU", 
    "employees" : [
        {
            "fullname" : "ALEJANDRO KOBBRT", 
            "status" : "approved", 
            "days" : 5.0
        }, 
        {
            "fullname" : "JOSE MELLADO", 
            "status" : "approved", 
            "days" : 1.0
        },
        {
            "fullname" : "MANUEL SOLIS", 
            "status" : "approved", 
            "days" : 4.0
        },
        {
            "fullname" : "MARSAL MELLADO", 
            "status" : "approved", 
            "days" : 4.0
        }
    ]
}
{ 
    "_id" : ObjectId("5f5e3ab682947e5e20fa4083"), 
    "base" : "ABC", 
    "zone" : "ABC CENTER", 
    "employees" : [
        {
            "fullname" : "ALEXIS MARAMBIO", 
            "status" : "approved", 
            "days" : 2.0
        },
        {
            "fullname" : "MARTA DIAZ CABELLO", 
            "status" : "approved", 
            "days" : 2.0
        }
    ]
}
{ 
    "_id" : ObjectId("5f5e3ab682947e5e20fa4082"), 
    "base" : "XYZ", 
    "zone" : "ABC WEST", 
    "employees" : [
        {
            "fullname" : "GUILLERMO BARROS", 
            "status" : "approved", 
            "days" : 4.0
        },    
        {
            "fullname" : "RODRIGO GONZALEZ", 
            "status" : "approved", 
            "days" : 4.0
        },         
        {
            "fullname" : "RONALD GONZALEZ", 
            "status" : "approved", 
            "days" : 1.0
        }
    ]
}

UPDATE

Thanks for helps, following aggregate works in my case.

db.getCollection("test").aggregate(
    [
        { $unwind: "$employees" }
        ,{ $sort: { "base": 1, "zone": 1, "employees.fullname": 1 } }
        ,{
            $group: {
                _id: { id: "$_id", base: "$base", zone: "$zone" },
                employees: { $push: "$employees" }
            }
        }
        ,{
            $project: {
               _id: "$_id.id",             
               base: "$_id.base",
               zone: "$_id.zone",
               employees: "$employees"
            }            
        } 
        ,{ $sort: { "base": 1, "zone": 1 } }       
    ]
);