Cordova / AngularJS / Ionic: Check if online and domain reachable

I'm developing an app where I want to download content (JSON) dynamically from my server. Before the download gets started I want to check if the device is online and my server is reachable.

Using Cordova it's very easy to get the network information (WiFi, Cellular, None, ...). But I've discovered a problem with WiFi networks which need a VPN connection. Without VPN Cordova returns WiFi but the app can't connect to the server. How can I check if the server is reachable?

I'm using Cordova with Ionic Framework (which uses AngularJS) and AngularJS's $http function to download my data.

Here is my current isOnline() service:

function() {
    var is_online;

    var network_state = navigator.connection.type;

    return ((network_state == 'unknown') || (network_state == 'none')) ? false : true;
}

This is how I download the data:

if(isOnline()) {
    var url = 'http://domain.com/file.json';

    $http({
        method: 'GET',
        url: url
    })
    .success(function(data, status, headers, config) {
        // save data
    })
    .error(function(data, status, headers, config) {
        // error
    });
}

Unfortunately the download function doesn't go to the error function if the server is not reachable.

Thank you very much for your help!