public void generateTakeoff() {
    Random rand = new Random(); // new random number

    if (rand.nextDouble()
        <= Glider.getProbability()) { // if number matches the Glider's probability
      Aircraft ac = new Glider(); // create new Glider object
      ac.setPrefix("tk_"); // debug info
      ac.setNumber(tcounter); // debug info
      to.addAircraft(ac); // add aircraft to the queue
      tcounter++;
    } else if (rand.nextDouble()
        <= (Glider.getProbability()
            + LightAircraft
                .getProbability())) { // if number matches the Light Aircraft's probability
      Aircraft ac = new LightAircraft(); // create new LightAircraft object
      ac.setPrefix("tk_"); // debug info
      ac.setNumber(tcounter); // debug info
      to.addAircraft(ac); // add aircraft to the queue
      tcounter++;
    } else if (rand.nextDouble()
        <= (Glider.getProbability()
            + LightAircraft.getProbability()
            + Commercial
                .getProbability())) { // if number matches the Commercial Aircraft's probability
      Aircraft ac = new Commercial(); // create new Commercial object
      ac.setPrefix("tk_"); // debug info
      ac.setNumber(tcounter); // debug info
      to.addAircraft(ac); // add aircraft to the queue
      tcounter++;
    }
  }
  public void generateLanding() {
    Random rand = new Random(); // new random number

    if (rand.nextDouble()
        <= Glider.getProbability()) { // if number matches the Glider's probability
      Aircraft ac = new Glider(); // create new Glider object
      ac.setPrefix("ln_"); // debug info
      ac.setNumber(lcounter); // debug info
      ln.addAircraft(ac); // add aircraft to the queue
      lcounter++;
    } else if (rand.nextDouble()
        <= (Glider.getProbability()
            + LightAircraft
                .getProbability())) { // if number matches the Light Aircraft's probability
      Aircraft ac = new LightAircraft(); // create new LightAircraft object
      Random gen = new Random(42); // Or choose a different seed
      int flyingTime = gen.nextInt(20) + 20; // time measured in half-minutes
      ac.setFuel(flyingTime); // set amount of fuel for the aircraft
      ac.setPrefix("ln_"); // debug info
      ac.setNumber(lcounter); // debug info
      ln.addAircraft(ac); // add aircraft to the queue
      lcounter++;
    } else if (rand.nextDouble()
        <= (Glider.getProbability()
            + LightAircraft.getProbability()
            + Commercial
                .getProbability())) { // if number matches the Commercial Aircraft's probability
      Aircraft ac = new Commercial(); // create new Commercial object
      Random gen = new Random(42); // Or choose a different seed
      int flyingTime = gen.nextInt(40) + 40; // time measured in half-minutes
      ac.setFuel(flyingTime); // set amount of fuel for the aircraft
      ac.setPrefix("ln_"); // debug info; //debug info
      ac.setNumber(lcounter); // debug info
      ln.addAircraft(ac); // add aircraft to the queue
      lcounter++;
    }
  }