Challenge 1
Aircraft currently navigate their vertical paths based on barometric pressure, which has several inherent limitations. The standard method involves using the ICAO Standard Atmosphere barometric formula, where altitude is calculated based on measured static pressure. This method assumes averaged atmospheric conditions, which leads to potential inaccuracies of several thousand feet against actual altitude. The only variable is the assumed reference pressure at sea level.
Different settings are used to manage this during various flight phases:
Flight Level (FL): During cruise, a standard setting for the sea level reference pressure(STD) is used, which maintains relative altitude accuracy (thus enabling vertical separation of aircraft) but lacks absolute precision.
QNH Setting: Near the ground, the reference pressure value is chosen to ensures the altitude at the runway threshold is displayed correctly.
QFE Setting: In sports aviation, the reference pressure value is chosen such that runway altitude is displayed as zero.
These settings can cause inefficiencies, especially during transitions between cruising and landing phases. The transition layer, where the pressure setting changes, introduces vertical profile inefficiencies and increases the risk of human error, which can result in safety incidents and higher fuel consumption.