string Land(ArialVehicle a)
{
if (Vehicles.Count < MaxVehicles) //airport is not full
{
Vehicles.Add(a);
a.IsFlying = false;
a.FlyDown(a.CurrentAltitude); //fly down to ground
}
else
{
return("The airport is full");
}
return(this + " has landed at the airport.");
}
string TakeOff(ArialVehicle a)
{
Vehicles.Remove(a);
return(a.TakeOff());
}