What problems occur when an altimeter fails?

When an altimeter fails, pilots may experience difficulties in maintaining safe altitude, leading to potential collisions with terrain or other aircraft. This failure can disrupt flight navigation and adherence to air traffic control instructions, resulting in dangerous situations, especially during takeoff and landing. Additionally, pilots may rely on other instruments, which can introduce errors if they are not properly calibrated or functioning. Ultimately, a malfunctioning altimeter compromises overall flight safety.