Unity/airplane/Assets/Scripts/FlyLogic.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class FlyLogic : MonoBehaviour
{
    public float YSpeed;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        float height = this.transform.position.y;
        if (YSpeed > 0 && height < 10) this.transform.Translate(0, Time.deltaTime * YSpeed, 0);
        if (YSpeed < 0 && height > 1) this.transform.Translate(0, Time.deltaTime * YSpeed, 0);
    }

    public void Fly()
    {
        YSpeed = 1;
    }

    public void Land()
    {
        YSpeed = -1;
    }
}