Wind check performs a number of aviation calculations or checks for the Boeing 737 prior to takeoff or landing.Entry of four parameters by toggle-able buttons and the ground wind (and Vref for landings) will result in the calculation of:- Approach speed for landing based on the FCTM procedures- Head/Tail and CrosswindThere will also be colour coded messages to advise of:- Crosswind limits and exceedances- Tailwind limit exceedances- Exceedance of door opening wind limits- Rolling takeoff recommendation- Approach speed is close to flap limit speed (and thus should a lower flap setting be used?)An aircraft graphic shows relative wind direction.The app currently has options for the 700 and 800 variants although this is only used to advise of approach speeds close to the selected flap limiting speed. The buffer applied for this caution is select-able by the user. Use the 800 option for the -800, -700IGW or -900 as these all have the same flap limiting speeds.