A pitot tube is a long tube like structure on planes that is used for measuring a wide variety of things important to pilots such as: speed, altitude, etc. To measure this, a pitot tube uses pressure within bernoulis equations as the main means of getting the airspeed and altitude of a plane.
Also, With the emergence of clouds layers coming in future updates, pilots might have to worry about new layer of frozen ice crystals due to condensation and freezing tenperatures in the clouds.
With icing conditions (such as in the clouds) the pitot opening can ice over. This can cause disruption in the ability for the pilot to get accurate information to very important measurements. To combat this a pilot should turn on pitot heat to negate this risk.
This will add a level and depth of new realism that can be seen through the sim.