Final answer:
When an EFD fails under IFR, the pilot should revert to backup instruments, inform ATC, maintain aircraft control, and follow emergency procedures which could include an emergency landing if needed.
Step-by-step explanation:
When an Electronic Flight Display (EFD) fails during Instrument Flight Rules (IFR), the pilot should follow established emergency procedures which typically involve reverting to the use of standby or backup instruments, and informing Air Traffic Control (ATC) of the failure. In such a scenario, maintaining aircraft control and situational awareness are paramount. The pilot must rely on traditional gyroscopic instruments like the attitude indicator, airspeed indicator, altimeter, and turn coordinator, which are part of a typical backup suite in most modern aircraft. They must also communicate the issue to ATC to receive additional support and guidance. Depending on the severity of the failure, an emergency landing may be necessary.