Two objects move synchronized issue (i think)

[AsDeadAsADodo]

So i have this scenario : two aeroplanes fly side by side and in the same altitude . let's call them aeroplaneA and aeroplaneB . There are two phases of their movement : the first one is that aeroplaneA and aeroplaneB maintain the movement , the other one is that aeroplaneB change its altitude fly down 10 unit while maintain the Horizontal speed.

 let groupA = new Group();
 let groupB = new Group();
 const speed = 300;
 const fullTime = 10; 
 let aeroplaneA_Tween = new TWEEN(aeroplaneA.position,groupA);
 let aeroplaneB_Tween_phase_one = new TWEEN(aeroplaneB.position,groupB);
 let aeroplaneB_Tween_phase_two = new  TWEEN(aeroplaneB.position,groupB);
 aeroplaneA_Tween.to({
 	z:aeroplaneA.position.z+speed*fullTime
 	},fullTime*1000);
 aeroplaneB_Tween_phase_one.to({
 	z:aeroplaneB.position.z+speed*fullTime/2
	},fullTime/2*1000);
 aeroplaneB_Tween_phase_two.to({
 	y : aeroplaneB.position.y-10 ,
 	z : aeroplaneB.position.z+speed*fullTime/2
	},fullTime/2*1000);
	aeroplaneB_Tween_phase_one.chain(aeroplaneB_Tween.phase_two);
	
	aeroplaneA_Tween.start();
	aeroplaneB_Tween_phase_one.start();
	
	......
	
	function animate(){
		groupA.update();
		groupB.update();
		...... //render canvas
		requestAnimationFrame(animate);
	}

But the thing is , at the very beginning of the phase two , I can see clearly aeroplaneB is fly behind aeroplaneA , they suppose to fly side by side .
I guess its because aeroplaneA is continue its movement while aeroplaneB phase two code is not executed fully.
AeroplaneA and aeroplaneB are simply not synchronized .
I dont know for sure . but if my deduction is right , how do i synchronized them ?

I noticed the user guide provide a way to synchronize things , but i dont understand .

        var currentTime = player.currentTime
        TWEEN.update(currentTime)

[trusktr]

Hello @AsDeadAsADodo. I am sorry for the late reply. I hope you have figured out a solution by now. But to answer the original question, you are creating both aeroplaneB_Tween_phase_one and aeroplaneB_Tween_phase_two at the same time. This means that the destination value for Z, for both animations is the same: aeroplaneB.position.z+speed*fullTime/2.

At the moment in time you execute that code to create your Tween instances, aeroplaneB.position.z+speed*fullTime/2 has the same value for both. That means, for both animations, the end result will be whatever aeroplaneB.position.z+speed*fullTime/2 was at the time you created the tweans.

I think what you need is aeroplaneB.position.z+speed*fullTime/2 for the first, and aeroplaneB.position.z+speed*fullTime for the second, because you want the first tween to go to the position at fullTime/2, then you want the second tween to go to the position at fullTime (the end time).