IFR Preflight When frost or dew is frozen on aircraft sfyou should turn on pitot heat to confirm that it is both working and capable of melting any internal ice as water through the drain hole. Pitot heat check (Pitot heat should be on in clouds and when outside air is within 10 degrees of freezing.) IFR Cockpit Check vacuum check Pitot heat Magnetic compass card check and set Altimeter set and error check VSI zeroed Clock set with ATC time check IFR Checks Pitot heat Time check Gyro check for noise Turn coordinator and heading indicator checked for turn Attitude indicator checked for no turn Taxi Checks Light checks Brake check Turn coordinator check Heading indicator check Approach Checks Timer Markers Beacons Identifiers