A Mach/airspeed indicator instrument has two pressure capsules each of which have a finger projecting from one face which is displaced by deflection of the capsule. Each finger is coupled to a respective arm that extends radially from respective shafts, so that displacement of a finger causes rotation of the respective shaft about its axis. Rotation of one shaft causes rotation of a Mach scale plate whereas rotation of the other shaft causes rotation of a pointer around an airspeed scale. The rear end of the Mach shaft is rotatably mounted at one end of a radially-extending lever that is in turn pivotally mounted close to its other end. The airspeed shaft is coupled with the Mach shaft by means of a link that extends between a plate fixed to the airspeed shaft and the lever. Rotation of the airspeed shaft thereby causes rotation of the lever and lateral displacement the Mach shaft about a pivot point at the end of the finger. This produces a rotational component about the axis of the Mach shaft that ensures linear displacement of the Mach scale plate.
A method and apparatus is disclosed for displaying a dynamic parameter of an aircraft, the apparatus comprises a display unit receiving a display signal and displaying a scale that changes dynamically and non-linearly in accordance with a selected display algorithm, the display unit further displaying a pointer pointing to said scale in accordance with a reading of said dynamic parameter, thereby emphasizing a range of said reading of said dynamic parameter.
