A little-told story from September 11, 2001 is that some of the fighters launched on that day had no ammunition aboard...and they were tasked with stopping further attacks...with their own planes.
Here is the story of Lt. Heather "Lucky" Penney as told by Washington Post reporter Steve Hendrix:
Late in the morning of the Tuesday that changed everything, Lt. Heather “Lucky” Penney was on a runway at Andrews Air Force Base and ready to fly. She had her hand on the throttle of an F-16 and she had her orders: Bring down United Airlines Flight 93. The day’s fourth hijacked airliner seemed to be hurtling toward Washington. Penney, one of the first two combat pilots in the air that morning, was told to stop it.
The one thing she didn’t have as she roared into the crystalline sky was live ammunition. Or missiles. Or anything at all to throw at a hostile aircraft.
Because the surprise attacks were unfolding, in that innocent age, faster than they could arm war planes, Penney and her commanding officer went up to fly their jets straight into a Boeing 757.
“We wouldn’t be shooting it down. We’d be ramming the aircraft,” Penney recalls of her charge that day. “I would essentially be a kamikaze pilot.”
Source: The Washington Post.