What action should be taken if Mode C fails above FL180?

In the event of a Mode C failure above FL180, informing your manager and the next air traffic controller as part of the communication protocol is crucial. At high altitudes, the accurate reporting of altitude is essential for maintaining safe separation between aircraft. By notifying your manager, you ensure that the situation is properly escalated and managed, which is vital in maintaining overall air traffic safety. Coordination with the next controller is also necessary to ensure they are aware of the situation and can adjust their plans accordingly, helping to prevent any potential complications in air traffic flow.

The emphasis on advising the next controller further acknowledges the collaborative nature of air traffic control, where situational awareness is shared to manage flights effectively. This coordinated response helps maintain safety and operational efficiency, especially in high-altitude airspace where the complexity of traffic and reliance on accurate altitude information is heightened.