Handling subscriptions for tasks run in an Angular zone

Question

My objective: To subscribe to an observable having an Angular zone. I use the background geolocation plugin to get the device location when the app is closed. And depending on the location, I want to stop a timer that would have been started by the user previously. I handle the timer stopping in my component.

geolocation.service.ts

startBackTracking(destLat, destLng)
{     
    return this.backgGeolocation.configure(config)
      .map((pos) => {
        this.zone.run(() => {
          this.lat = pos.latitude;
          this.lng = pos.longitude;          
          let isOnSite = this.isAtSite(this.lat, this.lng, destLat, destLng);
          return isOnSite;
        });
      });
}

handler.component.ts

this.geolocationService.startBackTracking(this.destLat, this.destLng)
    .subscribe((res) => {
        //stop timer depending on res
    }

My problem: When the app is closed, I know that the zone task will be running. But as the zone is run in a different context, will my subscription code execute when the app is closed? And/or is there a better way to handle subscriptions to Angular zones?