I know that I shall meet my fate Somewhere among the clouds above; (1-2)
The word "fate" clearly means death in these lines. But it makes us think of death as the speaker's destiny or purpose. Was he born to die? Was he supposed to become a pilot and die up in the "clouds above"?
No likely end could bring them loss (7)
Well this isn't a very positive outlook. The speaker essentially says that his "likely end" (i.e., his death) wouldn't really cause the people of Kiltartan to lose anything. How is that possible? Does his life not really matter?
A lonely impulse of delight Drove to this tumult in the clouds; (11-12)
The word "drove" is important here. The speaker isn't in control of his "fate." He was driven by an impulse that seems to control him and is responsible for sending him to his death amidst the "tumult."
The years to come seemed waste of breath, A waste of breath the years behind In balance with this life, this death (14-16)
That word "seemed" is important here. If the future only "seemed" a "waste of breath," that doesn't mean it actually is. It is possible, then, that "this life, this death" really isn't all that?