“No, no, no!” The instructor’s loud voice stopped the new student pilot poised to remove frost from the airplane’s windshield with a credit card.
Airplane windows are manufactured from transparent plastic, not glass. This plastic, commonly referred to by the trademarked name Plexiglas, or more generally as stretched acrylic, is much lighter than glass and reportedly 17 times stronger. It is an important safety feature since it is more resistant to shattering than glass.
Routine cleaning should be done with a product approved for use on Plexiglas. Aviation retailers sell various products approved for cleaning acrylics; your flight school or fixed-based operator can help you locate the appropriate product.
This brings us to the preflight inspection of the airplane windows. A dirty window facing the sun is impossible to see out of. Can you clearly see outside the airplane in all directions, not just the front windshield? Think about air traffic control calling out traffic alerts. Is that window clean and clear to help spot the other aircraft? Prior to every flight, evaluate all windows for overall security and clarity, and, when needed, clean windows with a rotating motion, not in the same direction.
Many pilots carefully read accident reports to minimize the possibility of repeating the same mistake. That is part of our risk management culture. In my student pilot days almost 60 years ago, I remember hearing the story of ATC pointing out traffic to a pilot whose final transmission reported that he could not see anything because of the sun’s glare on his windshield. It probably had not been properly cleaned.