An ink jet recording apparatus having a recording head includes an ink storage tank for storing ink to be supplied to the recording head, an ink path between the recording head and the ink storage tank, and an ink remain detector provided in the ink path. The ink remain detector has ink inflow and outflow ports and an ink chamber communicating therewith; at least a portion of a wall of the chamber is formed of a flexible film member. A separation of the flexible film member is detected by a detector means, responsive to a pressure decrease in the ink chamber. The flexible film member is biased so that it is not apart from the detector means. The displacement of the flexible film is limited so that the film is not displaced over a predetermined amount, and is limited when enough ink flows from the inflow port to the outflow port in the ink chamber.

A cabin pressure altitude monitor and warning system provides a warning when a detected cabin pressure altitude has reached a predetermined level. The system is preferably embodied in a portable, pager-sized device that can be carried or worn by an individual. A microprocessor calculates the pressure altitude from signals generated by a calibrated pressure transducer and a temperature sensor that compensates for temperature variations in the signals generated by the pressure transducer. The microprocessor is programmed to generate a warning or alarm if a cabin pressure altitude exceeding a predetermined threshold is detected. Preferably, the microprocessor generates two different types of warning or alarm outputs, a first early warning or alert when a first pressure altitude is exceeded, and a second more serious alarm condition when either a second, higher pressure altitude is exceeded, or when the first pressure altitude has been exceeded for a predetermined period of time. Multiple types of alarm condition indicators are preferably provided, including visual, audible and tactile. The system is also preferably designed to detect gas concentrations and other ambient conditions, and thus incorporates other sensors, such as oxygen, relative humidity, carbon dioxide, carbon monoxide and ammonia sensors, to provide a more complete characterization and monitoring of the local environment.

A wind warning system. The system includes: an alarm module configured to provide a audio signal; a power module configured to provide power to the alarm module; and a trigger module configured to trigger actuation of the alarm module. There is also a wind-speed sensor module configured to provide a signal to the trigger module when wind is detected having a speed higher than a predetermined threshold. The trigger module includes an electrically conductive protruding member. The wind-speed sensor module includes: a shaft member; a fan rotatably and slidably coupled to the shaft member; and a bias member coupled to the shaft member and in mechanical communication with the fan. Additionally, there is: a vertical shaft coupled to the shaft member; a tower rotatably coupled to the vertical shaft member. Moreover, there is an adjustment device that selectably adjusts a tension of the bias member, thereby altering a threshold.

A method of and a system for controlling personal air vehicle (PAV) traffic provides a take-off-and-landing zone, and a forward flight zone. The take-off-and-landing zone may be from the ground up to a first altitude. The forward flight zone may be from the first altitude up to a second altitude. A maximum airspeed is provided in the take-off-and-landing zone. Minimum and maximum airspeeds are provided in the forward flight zone. In the forward flight zone there is a single heading for each altitude. Any change in heading must be accompanied by a change in altitude.

A passive aircraft Traffic alert and Collision Avoidance device (TCAD) is based on sensing and responding to transponder replies of other aircraft to SSR interrogations. In order to avoid masking other aircraft replies by the host transponder TCAD repeatedly and randomly suppresses the host transponder and simultaneously listens for other aircraft replies. Suppression on each occasion is effective for an equal and predetermined duration which is much longer than a typical reply, in a preferred embodiment the suppression/listen duration is 725 .mu.s. In this embodiment the time between successive suppression/listen occasions is random between 725 .mu.s. and 5.025 ms. with an average value of about 2.9 ms. Digital signal processing is used to detect and discard garbled or overlapping replies. Each valid reply, exhibiting a minimum pulse amplitude, is decoded and correlated with a calibrated range parameter and given a time tag. Successive replies which match to within predetermined criteria in time and calibrated range are merged to track the positional relation between the host and other aircraft. The positional relation between other aircraft and the host are evaluated via a priority table in terms of relative altitude and range to locate that craft which poses the highest threat to the host. Parameters of such a craft are displayed. In the event a craft penetrates a shield of programmable size an audible alert is sounded. TCAD provides for shields for each of a plurality of flight regimes, such as terminal, standard and enroute. Selection among shields is via a single pushbutton. TCAD allows the pilot to program each of the different shield sizes. Peripheral functions such as altitude deviation alert, density altitude and barometric pressure correction for altitude reporting are also provided.