Since the background was completely white, the answer was actually very easy. I copied the image of the aircraft to the clipboard (Command/Ctrl A and then Command/Ctrl C) and then pasted it on top of the photo of the explosion (Command/Ctrl V).
In the layers palette, I pulled down the blend mode submenu (where you see the word 'normal') until I found 'multiply'. When this was selected, miraculously the white sky disappeared and all I was left with was what you see here.
In my Creative Techniques in Photoshop online course here at BetterPhoto.com, I discuss how to do techniques like this, and as part of the critique process I talk about technical know-how as well as the artistry that goes into making images with impact.
About Author / Instructor / Photographer, Jim Zuckerman
In 1970, I decided to abort my intended career as a doctor in favor of photography and have never regretted it. Photography has enriched my life more than I can tell you. My career has taken me to over 60 countries, and I've seen and photographed wondrous things.
For 25 years, I shot a medium format camera, specifically the Mamiya RZ 67, for its superior quality. When I would lecture, I’d project the large, glass mounted transparencies, and it was really an incredible experience to see the brilliant color saturation and resolution of these slides. However, I went digital in 2004 because the technology finally equaled or surpassed medium format. I now shoot the Canon 1Ds Mark II digital camera with a variety of lenses.
I am the author of 12 books on photography. My work is sold in 30 countries around the world, and my images have appeared on scores of magazine and book covers, calendars, posters, national ads, trade ads, brochures, and corporate promotions.
For many years I've led photography tours to exotic places. These include Papua New Guinea, Thailand, Burma, Greece, The Czech Republic and Slovakia, Spain, Morocco, and Peru.