Wrong result although code should be correct.

Hello, I have t$$anonymous$$s little project here w$$anonymous$$ch actually seems quite simple. I have to calculate the destination, given start point, distance and bearing. I have done some research and found t$$anonymous$$s:

With the same values my programm spits t$$anonymous$$s out:

My programm-code:

 import UnityEngine.UI;
 
 //INPUT STRINGS
 var input1 : String;
 var input2 : String;
 var input3 : String;
 var input4 : String;
 
 //INPUT FIELDS
 var inputF1 : InputField; //input Field 1
 var inputF2 : InputField; //__""__ 2  
 var inputF3 : InputField; //...
 var inputF4 : InputField; //...
 var result : Text;
 
  private final var R : float = 6371000; //Earth's radius in metre
 
 //INPUT VARIABLES
 var d : float; //distance to travel
 var a1 : float; //latitude in dezimals
 var b1 : float; //longitude in dezimals
 var brng : float; //Angle you are going to
 
 function Start () {
 
 }
 
 function Update () {
 
 }
 
 //
 //BUTTON FUNCTIONS
 //
 function ExitButton(){
     Application.Quit();
 }
 
 function InputF1(){
     input1 = inputF1.text;
 }
 
 function InputF2(){
     input2 = inputF2.text;
 }
 
 function InputF3(){
     input3 = inputF3.text;
 }
 
 function InputF4(){
     input4 = inputF4.text;
 }
 
 function Calc(){
     d = float.Parse(input3);
     a1 = float.Parse(input1);
     b1 = float.Parse(input2);
     brng = float.Parse(input4);
     
     brng = brng * Mathf.Deg2Rad;
     a1 = a1 * Mathf.Deg2Rad;
     b1 = b1 * Mathf.Deg2Rad;
     
     var a2 : float = Mathf.Asin( Mathf.Sin(a1)*Mathf.Cos(d/R) +
                         Mathf.Cos(a1)*Mathf.Sin(d/R)*Mathf.Cos(brng) );
     var b2 : float = b1 + Mathf.Atan2(Mathf.Sin(brng)*Mathf.Sin(d/R)*Mathf.Cos(a1),
                              Mathf.Cos(d/R)-Mathf.Sin(a1)*Mathf.Sin(a2));
     result.text = a2 * Mathf.Rad2Deg+"°N "+b2 * Mathf.Rad2Deg+"°W "; 
 }
 //
 //BUTTON FUNCTIONS END
 //
 

My input is the same and strangely the first value (a2 in my script), latitude is always exactly right. The longitude however is always off by quite a bit. I have compared the two scripts over and over again. I just can´t figure out what the problem is.

I am not asking for any scripts, but some help would be awesome! Anyt$$anonymous$$ng that I could have missed?

Anyways, thanks for the help in advance!