<p>Three U.S. Army Air Corps Keystone B-5A bombers of the 72nd or 23rd Bomb Squadron, 5th Composite Group, take off at Luke Field, Hawaii, in 1933. The U.S. Naval Base Pearl Harbor is in the background.
</p>
(The National Museum of the U.S. Air Force's <a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil/Upcoming/Photos/igphoto/2000557387/">current gallery page for this image</a> labels this as an image of the Keystone <b>B-4A</b>.)
USAF
1933
<a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil/photos/index.asp">National Museum of the U.S. Air Force</a> photo <a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil/shared/media/photodb/photos/060421-F-1234P-014.jpg">060421-F-1234P-014</a>