What is the uncertainty in using pressure measurement as an altimeter? A gage on an airplane measures a local pressure of 54 kPa with an uncertainty of 3 kPa. The lapse rate is 0.006 K/m with an uncertainty of 0.001 K/m. Effective sea-level temperature is 10°C with an uncertainty of 5°C. Effective sea-level pressure is 100 kPa with an uncertainty of 2 kPa. Estimate the plane’s altitude and its uncertainty.