[raaaid]

well you make a mechanism that makes this calculation:

airspeed*cos pitch angle=climbing rate

if your going at 500kph and theres a vertical wind of 20 kph your making an error in just that your real speed will be the hipothenusa of the rect triangle: 20-500-x

so then your horizontal airspeed would be maybe 490 with which the error would be minimum

also planes have artificial horizonts to know your picth angle

edit:

doesnt actually a gyro artificial horizont also go crazy in hard manoubers?