What is the recommended action if the altimeter setting is incorrect?

When the altimeter setting is incorrect, the recommended action is to adjust flight altitude accordingly. This is crucial because an incorrect altimeter setting can lead to an inaccurate altitude reading, which may put the aircraft at risk of a collision with terrain or other aircraft. By adjusting your altitude to take into account the corrected setting, you ensure that you maintain safe vertical separation from obstacles and comply with airspace regulations.

Setting the altimeter to the maximum allowable pressure would not provide an accurate indication of the aircraft's altitude relative to sea level and could further contribute to altitude errors. Contacting the control tower immediately is typically not the quickest or most efficient way to address a discrepancy with an altimeter setting, as it is the pilot's responsibility to manage altimeter settings based on current pressure readings. Correcting the altimeter only before takeoff could lead to issues during flight if atmospheric pressure changes, thus it is vital to adjust the altimeter setting in accordance with the latest reported pressure as needed throughout the flight.