//Plane arrive to the airport's airspace and request landing. public void NewLandingRequest(Plane plane) { if (!IsThereLandingWaiter()) { RunwayStation runway = GetRunwayToLand(); if (runway != null) { Land(plane, runway); return; } } LandingWaiters.Add(plane); notifyService.NewLandingWaiter(plane); //db update }