A breathing gas supply system for an aircraft includes a plurality of oxygen concentrating apparatus, each of which in use, is operable to supply oxygen enriched gas to a breathing gas supply. The data acquisition also includes a winch rope rotatably coupled to a mounting plate and a sensor module coupled to the kite. The method requires only one high precision measurement, which is the depth of the two calibration points from a reference plane. The reference layer may be incorporated in STT-MRAM memory elements or in spintronic devices including a spin transfer oscillator. A current time provided by the time detector is compared to a time-based criterion, and a current geographical location provided by the location detector is compared to a location-based criterion to determine whether or not to generate an alarm. The package may further include a package structure receiving the center element and support element therein, and including an opening for viewing the product and manually rotating the center element.