Foo Fighters
Partially explainedSummary
In the last winter of the Second World War, Allied aircrew flying at night over Germany began reporting glowing balls of light that appeared beside their aircraft, kept pace with them, and would not go away.
They assumed it was a German secret weapon.
Later accounts say German and Japanese aircrew reported the same thing. If three air forces at war with each other all saw it, and none of them built it, then nobody built it. The Allied reports are well documented; the German and Japanese ones are known mainly from those later accounts.
What is documented
The reports. From late 1944, aircrew of the United States 415th Night Fighter Squadron, flying over Germany and occupied France, reported luminous objects: balls of light, often red or orange, appearing beside or behind their aircraft, holding station with them, and sometimes manoeuvring.
The name. Coined within the 415th, from the comic strip Smokey Stover, whose fire-fighting protagonist was in the habit of announcing that where there's foo, there's fire.
The scale. Reports came from many crews, over months, and were taken seriously enough to be investigated during the war.
The enemy may have seen them too. Later accounts report that German aircrew saw comparable phenomena, and so did Japanese aircrew in the Pacific. These reports are not documented as fully as the Allied ones.
Nobody built them. The Allied investigation found no evidence of a German weapon. The post-war examination of German aeronautical and rocketry programmes, which recovered a great deal of material and questioned many of the people involved, found nothing corresponding to a foo fighter.
Leading explanations
Electrical phenomena on and around the aircraft. The leading family of explanations, and there is more than one member of it.
St Elmo's fire. Corona discharge from the extremities of an aircraft flying through a charged atmosphere. It appears at propeller tips, wingtips and antennae, and it glows. Aircrew see it regularly and it is well understood. (See AR-0058.)
Ball lightning. A real phenomenon, spectroscopically recorded in 2012, and reported from inside aircraft as well as outside them. (See AR-0016.)
Static discharge and plasma effects around a metal airframe moving fast through cold, charged air.
Misidentification. Flak bursts. Tracer. Other aircraft. Planets and bright stars near the horizon. Reflections on canopies. All of these are present in enormous quantity in a night sky over a war.
Autokinesis. This one deserves stating because it is not intuitive and it is very powerful.
A single static point of light, seen against a dark and featureless background with no reference points, will appear to move. This is a property of the human oculomotor system, not of the light. It is well characterised, it is reproducible in a laboratory, and it is the reason a star seen through a cockpit canopy on a black night will seem to drift, dart, and pace you.
A crew flying at night, with nothing to fix their eyes on, watching a distant light, will see it move. It will seem to follow them. And it will not be moving at all.
A secret weapon. Ruled out, and by the strongest available means: the victors searched for it in the defeated side's records, and questioned its scientists, after the war.
What the popular version gets wrong
"Trained pilots would not misidentify anything." Trained pilots misidentify things constantly, and they know it, which is why they are trained. Night flying, over hostile territory, under fire, at the edge of exhaustion, in an aircraft full of static and vibration, is close to the worst set of observing conditions that has ever existed, and the men doing it were not observers. They were being shot at.
"They were German secret weapons." Later accounts say German aircrew were reporting them too. When United States Air Force intelligence questioned German scientists, engineers and senior Luftwaffe officers in the autumn of 1945, none of them knew of any such weapon.
"It was covered up." It was investigated during the war, by people who badly needed to know whether the enemy had a new weapon, and reported on. In March 1945 the British Air Ministry judged flak rockets the most likely explanation and called the affair still something of a mystery. No evidence of a new weapon was found.
"Nobody knows what they were." Several well-understood physical phenomena account for most reports, and the human visual system accounts for a great deal of the rest, and the residue is small and is not evidence of anything in particular.
Current status
Partially explained. No single cause accounts for every report, and no single cause needs to, because "foo fighter" was a name applied by frightened men to anything luminous they could not identify, over a battlefield, at night.
The registry keeps this record for one argument, which is the cleanest of its kind in the archive.
The Allies suspected a German weapon. Later accounts say German and Japanese aircrew saw the same kind of light.
Three air forces, actively at war, with every incentive in the world to build such a thing and every incentive to find out whether the enemy had, and none of them had, and none of them found one.
That is not weak evidence of a natural phenomenon, although it leans on the enemy reports, which are the least documented part of the record.
Sources
- United States 415th Night Fighter Squadron, operational reports, late 1944 to 1945.
- Contemporary Allied intelligence assessments of possible German secret weapons.
- Post-war examination of German aeronautical and rocketry programmes.
- Later accounts of German and Japanese aircrew reports of comparable phenomena. The registry has not traced these to wartime documents.
- United States Air Force in Europe intelligence interviews with German scientists, engineers and former senior Luftwaffe officers about "balls of fire" reports, early autumn 1945.
- British Air Ministry reply on the foo fighter reports, 13 March 1945.
- Literature on St Elmo's fire, ball lightning, static discharge on airframes, and autokinesis.
Last reviewed: September 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.