New Page getting open inside tabs view instead of opening as new page

Ionic Framework ionic-v3
1

I am using tabbed view in my Ionic 2 RC0 App. When I do this.nav.push the new page is getting opened in the tab instead of opening as a new page? What am I doing wrong here?

export class Tab1Page {
  
  constructor(public nav: NavController) {
  }

  editRecord(index){
    this.nav.push(MyCustomPage, {indexoEdit: index});
  }
}