 The worst of the weather behind them now, they swung east for the long straight run to Germany, still descending, down to 3,000 feet or below.Although the German radar belt extended through eastern France to the Swiss frontier, extreme low flying was not considered necessary or advisable.Upland terrain restricted the enemy's radar coverage, and the heavily laden, slow-climbing bombers needed enough height in hand to cross the southern edge of the Vosges mountain range just before the Rhine.