What action should you take if instructed to hold while at a fix?

When instructed to hold while at a fix, commencing a standard holding pattern based on your altitude is the correct action to take. Standard holding patterns are designed with specific configuration criteria, including entry procedures, dimensions, and turn directions, which generally involve flying a racetrack pattern around the fix.

For example, when initiating a standard hold, you'd enter the hold according to the published entry procedure (which may vary depending on your aircraft's current path and the pattern's orientation) and conduct turns as directed, usually with a specified time or distance for each leg.

Following this procedure ensures proper adherence to air traffic control instructions and maintains safe separation from other aircraft. Additionally, it's essential to maintain the correct altitude for the holding pattern as specified in the holding instructions and to manage your airspeed as necessary.

While there may be situations where holding is contingent on specific instructions or altitudes from air traffic control, the standard procedure in absence of such specific directives is to proceed with a standard holding pattern.