Major Martin Vcttcr kept a close eye on the radio altimeter although he knew that if he unwittingly descended to 15 m, the alarm would sound. It was a late evening in July and as dusk fell, the flight, at an altitude of 30m, was getting rather unpleasant. The gray waves of the North Sea rolled below the wide wings of the He 111. These were cold and merciless waters waiting for new victims. The slightest mistake could result in a crash and death of the crew. Such a fate had befallen many because the correct assessment of altitude in flight close to sea level is basically impossible without the necessary equipment. It took very strong nerves not to think about it. Flying higher was out of the question - the He 111 would have been immediately detected by British radar...