Ravenfield Landable Planes Script. Tested through to EA12, may work in newer versions.

script.cs

/*
1. Create a bool `down` in the Plane script class.
2. Insert the below code in the methods in the Plane class.
*/

void Update() {
  // Insert at the end
  if (Input.GetKeyDown(KeyCode.Z) && this.seats[0].IsOccupied() && !this.seats[0].occupant.aiControlled)
  {
    if (this.down) {
      this.down = false;
    } else {
      this.down = true;
    }
    this.animator.SetBool("landing gears", this.down);
  }
}

void FixedUpdate() {
  // Replace `this.rigidbody.AddForce(...)` with this.
  if (this.animator.GetBool("landing gears") && !this.isAirborne && vector.z < 10f && this.seats[0].IsOccupied() && !this.seats[0].occupant.aiControlled)
  {
    this.rigidbody.drag = 1.5f;
    this.engine.enabled = false;
  }
  if (SteelInput.GetAxis(SteelInput.Inputs.PlaneThrottle) < 0f && this.seats[0].IsOccupied() && !this.seats[0].occupant.aiControlled)
  {
    this.rigidbody.AddForce(force * 0.3f, ForceMode.Acceleration);
  }
  else
  {
    if (this.seats[0].IsOccupied() && !this.seats[0].occupant.aiControlled)
    {
      this.engine.enabled = true;
    }
    this.rigidbody.drag = 0.12f;
    this.rigidbody.AddForce(force, ForceMode.Acceleration);
  }
}