Code of Flex App:
<?xml version=“1.0” encoding=“utf-8”?>
<s:Application
xmlns:fx=“http://ns.adobe.com/mxml/2009”
xmlns:s=“library://ns.adobe.com/flex/spark”
xmlns:mx=“library://ns.adobe.com/flex/mx”
xmlns:a3d=”*”  backgroundAlpha=“0” creati viewSourceURL=“srcview/index.html” >
<s:HGroup width=“100%” height=“100%”>
  <a3d:AwayView id=“awayview” width=“100%” height=“100%” >
</s:HGroup>
</s:Application>

And now code of UIComponent for Away3d 4:
<?xml version=“1.0” encoding=“utf-8”?>
<mx:UIComponent xmlns:fx=“http://ns.adobe.com/mxml/2009”
  xmlns:s=“library://ns.adobe.com/flex/spark”
  xmlns:mx=“library://ns.adobe.com/flex/mx”
  width=“100%”
  height=“100%”>
<fx:Script>
  <![CDATA[
  import away3d.cameras.Camera3D;
  import away3d.containers.Scene3D;
  import away3d.containers.View3D;
  import away3d.debug.Trident;
  import flash.events.Event;
 
  protected var _view:View3D;

  override protected function createChildren():void
  {
  super.createChildren();
  _view = new View3D();
  /*
  var myScene:Scene3D = new Scene3D;
  _view.scene =  myScene;
  addChild(_view);
  _view.addEventListener(Event.ADDED_TO_STAGE, update);
  _view.addEventListener(Event.ENTER_FRAME, onEnterFrame);
  // Create Axes Reference
  var _axes:Trident = new Trident();
  _view.scene.addChild(_axes);
  */
  }
 
  override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
  {
  /*
  super.updateDisplayList(unscaledWidth, unscaledHeight);
  update();
  */
  }
 
  private function update(e:* = null):void
  {
  /*
  if(_view.stage)
  {
  _view.width = unscaledWidth;
  _view.height = unscaledHeight;
  }
  */
  }
 
  protected function onEnterFrame(event:Event):void
  {
  /*
  _view.render();
  */
  }
  ]]>
</fx:Script>
</mx:UIComponent>

And finally error reported at runtime:

VerifyError: Error #1014: Class flash.display3D.textures::Texture could not be found.

at AwayView/createChildren()[/Users/lvignals/Documents/Adobe Flash Builder 4.5/Away3d4MXMLApp/src/AwayView.mxml:20]
at mx.core::UIComponent/initialize()[E:dev4.5.1frameworksprojectsframeworksrcmxcoreUIComponent.as:7624]
at AwayView/initialize()
at mx.core::UIComponent/http://www.adobe.com/2006/flex/mx/internal::childAdded()[E:dev4.5.1frameworksprojectsframeworksrcmxcoreUIComponent.as:7485]
at mx.core::UIComponent/addChildAt()[E:dev4.5.1frameworksprojectsframeworksrcmxcoreUIComponent.as:7189]
at spark.components::Group/addDisplayObjectToDisplayList()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:2037]
at spark.components::Group/http://www.adobe.com/2006/flex/mx/internal::elementAdded()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:1628]
at spark.components::Group/setMXMLContent()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:633]
at spark.components::Group/createChildren()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:855]
at mx.core::UIComponent/initialize()[E:dev4.5.1frameworksprojectsframeworksrcmxcoreUIComponent.as:7624]
at mx.core::UIComponent/http://www.adobe.com/2006/flex/mx/internal::childAdded()[E:dev4.5.1frameworksprojectsframeworksrcmxcoreUIComponent.as:7485]
at mx.core::UIComponent/addChildAt()[E:dev4.5.1frameworksprojectsframeworksrcmxcoreUIComponent.as:7189]
at spark.components::Group/addDisplayObjectToDisplayList()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:2037]
at spark.components::Group/http://www.adobe.com/2006/flex/mx/internal::elementAdded()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:1628]
at spark.components::Group/setMXMLContent()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:633]
at spark.components::Group/set mxmlContent()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsGroup.as:573]
at spark.components::SkinnableContainer/set mxmlContent()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsSkinnableContainer.as:657]
at spark.components::SkinnableContainer/createDeferredContent()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsSkinnableContainer.as:1050]
at spark.components::SkinnableContainer/createContentIfNeeded()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsSkinnableContainer.as:1078]
at spark.components::SkinnableContainer/createChildren()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsSkinnableContainer.as:885]
at spark.components::Application/createChildren()[E:dev4.5.1frameworksprojectssparksrcsparkcomponentsApplication.as:1480]
...I cut some unneeded stuff here to fit in the form’s maximum length…
mx.managers.systemClasses::ChildManager/initializeTopLevelWindow()[E:dev4.5.1frameworksprojectsframeworksrcmxmanagerssystemClassesChildManager.as:359]
at mx.managers::SystemManager/initializeTopLevelWindow()[E:dev4.5.1frameworksprojectsframeworksrcmxmanagersSystemManager.as:3063]
at mx.managers::SystemManager/http://www.adobe.com/2006/flex/mx/internal::kickOff()[E:dev4.5.1frameworksprojectsframeworksrcmxmanagersSystemManager.as:2849]
at mx.managers::SystemManager/http://www.adobe.com/2006/flex/mx/internal::preloader_completeHandler()[E:dev4.5.1frameworksprojectsframeworksrcmxmanagersSystemManager.as:2729]
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.preloaders::Preloader/timerHandler()[E:dev4.5.1frameworksprojectsframeworksrcmxpreloadersPreloader.as:542]
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()