Why is my Cordova Geolocation so inaccurate - angularjs

Question

I'm working on a Track & Share Module for Pilots, the app is build with AngularJS within Ionic and Cordova framework. I'm currently developting and testing for android only.
The case:
There are four buttons, first checks if gps is enabled, second starts the tracking, third stops the tracking, fourth send the trackdata to the web-API if internet connection is stable. I can't guarantee 100% connectivity up in the air, so I can't send the trackdata on every tracked waypoint direct to the api - I have to store it until the aircraft is on the ground again.
The problem:
The tracked waypoints are (1) temporally/timely highly variable (I can't get any pattern on my test-tracks) and (2) the tracked altitude/heading/speed data isn't recorded on some trackpoints.
My flown test-route is about 40 minutes. I'm tracking every 60 seconds. So I must get at least minimum 35-40 trackpoints. But: I just get between 9 and 15 trackpoints on that route..
Trackpoints:
1442050712218|51.4514495|6.8892898|null|null|null; 12.9.2015 11:38:32
1442051327924|51.5183441|6.8183962|null|null|null; 12.9.2015 11:48:48
1442051511529|51.8569473|6.8611548|null|null|null; 12.9.2015 11:51:52
1442051732401|51.9828794|6.9063169|null|null|null; 12.9.2015 11:55:32
1442051912503|52.0233909|6.9596959|1300|64|52.25; 12.9.2015 11:58:33
1442052014828|52.0400627|7.0322238|1332|75|51.25; 12.9.2015 12:00:15
1442052517583|52.1472176|7.3813409|1307|70|51.5; 12.9.2015 12:08:38
1442052746410|52.1859082|7.5392811|1217|68|53; 12.9.2015 12:12:26
1442053119338|52.224271|7.874347|null|null|null; 12.9.2015 12:18:39
1442053401324|52.2677044|7.9679879|null|null|null; 12.9.2015 12:23:21
.service('TrackingFunctions', ['$interval', '$rootScope', '$localstorage', function($interval, $rootScope, $localstorage) {
// Erstellt einmalige "global" Referenz, dass immer die selbe Instanz angesprochen wird
var tracker;
this.doTracking = function(execTracking){
if(!execTracking){ // if no tracker start new
$localstorage.TRACKDATA = [];
return $interval(function(){
$localstorage.isTrackerActive = true;
var geo_options = {
enableHighAccuracy: true,
maximumAge: 30000,
timeout: 20000
};
function geo_success(position) {
console.log(position);
var tsmp = position.timestamp;
var lat = position.coords.latitude;
var lng = position.coords.longitude;
var alt = position.coords.altitude;
var hdg = position.coords.heading;
var spd = position.coords.speed;
var ARRAYDATA = tsmp + "|" + lat + "|" + lng + "|" + alt + "|" +hdg + "|" + spd + ";";
$localstorage.TRACKDATA.push(ARRAYDATA);
}
function geo_error() {
//$scope.alt = "Fehler " + error.message + ' Error Code: ' + error.code;
}
var wpid = navigator.geolocation.getCurrentPosition(geo_success, geo_error, geo_options);
},60000); // getrackt wird alle 60 Sekunden
} else { // if tracker cancel
$interval.cancel(execTracking);
console.log("tracker deaktiviert!");
}
};
}])
How can I fix that the app tracks every 60 seconds and the missing data will be recorded, too? The function is crucial fot the app and webservice for flight-training for solo-flights of the student pilot.
Thank you.

Answer 1

Just an idea:
The timeout is not a accurate task, that means, timeout is working when all other tasks are done. It's more like: You should run every 60 seconds.
In your case, I would save the position continuous and would write a «clock/timer», called every second. In your script you calculate the exact starttime, e.g.: 09:27:16. After starttime + x * 60 seconds you trigger in your clock the final saving of the position.
If this is not working, I would test it by using a Web Worker.