Final answer:
The altimeter setting is valid for a certain period of time before it needs to be updated, typically every 12 hours.
Step-by-step explanation:
The altimeter setting, also known as the barometric pressure setting, is valid for a certain period of time before it needs to be updated. The standard interval for updating the altimeter setting is every 12 hours.
This is because the atmospheric pressure can change due to weather conditions, altitude changes, and other factors. Pilots and aviation professionals rely on accurate altimeter readings for safe navigation, so it is important to update the setting regularly.
For example, if a pilot takes off at 9:00 AM and the altimeter setting is valid until 9:00 PM, they would need to update the setting before their next flight if it is scheduled after 9:00 PM.