Which military branch provided the first major validation of the ballpoint pen's reliability at altitude?

Answer

The British Royal Air Force

The British Royal Air Force quickly adopted the ballpoint because its sealed system performed consistently during rapid air pressure changes, unlike standard fountain pens which often leaked catastrophically.

Which military branch provided the first major validation of the ballpoint pen's reliability at altitude?

#Videos

How This Pen Changed The World - YouTube

inventionHistorywritingtoolpen