ALTIMETER ERRORS,

The barometric altimeter is essentially a manometer for measuring the static pressure outside an airplane and has three principal errors 1 the methodical error caused by the deviation of the actual from the standard atmosphere 2 instrumental error and 3 error associated with airflow past altimeter air-pressure sensor. The author states that true flight altitude is to be found from the formula given in the text. It is difficult for the pilot to do more than add the instrumental correction the others are provided by flight control. This requires correction graphs for all planes operating from a given field. Experience has shown that when due allowance is made for errors in barometric altimeter readings these instruments contribute to flight safety.