| > ridiculous I don’t think that word means what you think it means. Baro altimeters don’t tell you your height above the ground (or other obstruction). A digital terrain model is only as good as your navigation source, and GPS has well known failure modes. > do these airplane systems have no clue about filtering? Do you have no clue how much it costs to retrofit a filter on a commercial airplane? It’s not that adding a filter is technically challenging. It’s that it wasn’t previously a requirement, and leaving it out saved weight (and every gram adds up when you’re building an airplane). If you added every ‘nice to have’, the airplane couldn’t lift its own weight. Now that radar altimeters exist without high Q filters, retrofitting them costs money. You’ll need to have the filter approved by the manufacturer (because you are normally required to follow their installation guidance) and the FAA. Neither of them are going to help you for free. |