test

var czml = [{
    "id" : "document",
    "name" : "CZML Model",
    "version" : "1.0"
}, {
    "id" : "aircraft model",
    "name" : "Cesium Air",
    "position" : {
        "cartographicDegrees" : [-77, 37, 10000]
    },
    "model": {
        "gltf" : "../../SampleData/models/CesiumAir/Cesium_Air.glb",
        "scale" : 2.0,
        "minimumPixelSize": 128
    }
}];

var viewer = new Cesium.Viewer('cesiumContainer');
var dataSourcePromise = viewer.dataSources.add(Cesium.CzmlDataSource.load(czml));

dataSourcePromise.then(function(dataSource){
    viewer.trackedEntity = dataSource.entities.getById('aircraft model');
}).otherwise(function(error){
    window.alert(error);
});