Cockpit pressurization and oxygen warning system

A cockpit pressurization and oxygen warning system in an aircraft flown by a pilot and having an aircraft altitude and a cabin altitude, comprising:

• (a) a cabin pressure input;
• (b) an aircraft pressure input;
• (c) a pilot interface including a first visual indicator having a first recognizable characteristic disposed in a first position that is made visually perceptible when a first signal is asserted and a second visual indicator having a second recognizable characteristic aesthetically different from the first recognizable characteristic and disposed in a second position different from the first position that is made visually perceptible when a second signal is asserted, the pilot interface including an electronic display and a manual mode input and wherein the electronic display is configured to display a numerical cabin altimeter;
• and
• (d) a control circuit that is responsive to the cabin pressure input and the aircraft pressure input that determines an acceptable range for the cabin altitude that corresponds to the aircraft altitude and that determines the cabin altitude as a function of the cabin pressure input and that asserts the first signal only when the cabin altitude is within the acceptable range and not when the cabin altitude is not within the acceptable range, and that asserts the second signal only when the cabin altitude is not within the acceptable range and not when the cabin altitude is within the acceptable range,
• wherein the mode input comprises a button that, when depressed, asserts a mode signal sensed by the control circuit, wherein when the mode signal is asserted the control circuit causes the electronic display to cycle to a display mode selected from a plurality of display modes including:
• a numerical cabin altimeter;
• a numerical cabin altimeter with rolling numbers;
• and a bar graph representation of cabin altitude over time.

A method of presenting pressurization information to a pilot about an aircraft having a cabin pressure and an aircraft altitude, comprising the steps of:

• (a) determining a cabin altitude based on the cabin pressure in which the cabin altitude is the aircraft altitude at which outside air pressure equals the cabin pressure;
• (b) comparing the cabin altitude to an acceptable cabin altitude range for a current value of the aircraft altitude;
• (c) illuminating a situation normal indicator light only when the cabin altitude is within an acceptable range and not illuminating the situation normal indicator light when the cabin altitude is not within the acceptable range, the situation normal indicator light being disposed at a first position and having a first color and a first shape;
• and
• (d) illuminating a cabin pressurization warning indicator light only when the cabin altitude is not within an acceptable range and not illuminating the cabin pressurization warning indicator light when the cabin altitude is within the acceptable range, the warning indicator light being spaced apart from the first visual indicator and having a second color different from the first color and a second shape different from the first shape.