Abstract: An improved instrument for measuring low indicated air speed greatly reduces variation with one or more of time, temperature, and ambient pressure change. This is accomplished by periodically re-zeroing the transducer using only a single electronically controlled valve. Re-zeroing may be initiated in response to a change in the internal temperature of the transducer.

Abstract: A warning system alerts a helicopter pilot that a low-G condition is imminent or occurring. The low-G alert employs an accelerometer to detect a vertical acceleration of the aircraft. Higher frequency vibrations in the output of the accelerometer are removed by a filter to provide a clean signal representing vertical acceleration of the aircraft. This signal is processed by a central processing unit (CPU) to perform a threshold detector function. The CPU is configured to detect the possibility of the onset or occurrence of a low-G event. Upon detection, the CPU triggers an audible alert to announce “Low-G. Pull aft.” or the like until the low-G event has been corrected or avoided.