"And most of these pilots were lost during the first five flights"

The quote by Adolf Galland is referring to the high mortality price of pilots during the beginning of aviation. He is claiming that the majority of pilots that were flying throughout the very first 5 flights ended up losing their lives. This can be taken an observation of the early risks dealt with by aeronautics pioneers, such as the Wright Brothers, that flew their initial aircraft in 1903. Galland's comment additionally highlights the threats of examining new innovation and pushing limits in quest of progress. On the whole, the quote is a suggestion of the sacrifices made by very early aviators in paving the way for the air travel sector we have today.