Much feared by military aircrew, flak blew thousands of aeroplanes from the sky across the 20th century. We grilled Donald Nijboer author of Flak in World War II, about the dreaded flak.

What is Flak?

“Flak is an acronym/initialism for the German word, Flugabwehrkanone, meaning aircraft-defence cannon. When the Allies began to use the term is not known. It’s interesting that we continue to use the term today…’catching flak at the office’ as one example.”

How effective was it in WW2? 

“Flak in the Second World War was very effective. Most of the official Allied histories downplayed its role. Many postwar histories accepted the testimony of leading figures within the Luftwaffe that ground based AA defences achieved limited success in destroying Allied bombers.  After the war, the British Bombing Survey Unit (BBSU) continued this line of thinking describing German AA defences as “plentiful” but not “very lethal.” At the same time the official RAF history of the air war estimated that German flak accounted for 37 percent of Bomber Command’s losses between July 1942 and April 1945. Low and medium level flak was even more effective. More American 8^th Air Force aces were shot down by flak than enemy fighters.”

How does it compare with fighter interceptors for effectiveness?

“The Germans and the Allies, to a certain extent, used the number of enemy aircraft shot down by fighters and those by flak as a measurement as to its effectiveness. But this was a false metric. It must be remembered that Flak defences were designed, not to shoot bombers down, but to force them to drop their loads from a higher altitude and thus reduce their accuracy. Aircraft shot down or damaged was a bonus. Flak proved a huge benefit to fighter pilots assigned to attack incoming raids. Flak-damaged bombers were forced out of formation, making them easy prey (for both Allied and Axis fighter forces) for marauding fighters. Flak damaged tens of thousands of bombers. These bombers required repair, causing service rates to fall and thus reducing the number of bombers available for new operations. AA shrapnel also killed and wounded tens of thousands of aircrew, significantly reducing the overall efficiency and morale.”

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How many shells are fired to down an aircraft? 

“The figure of 16,000 rounds of German 88mm ammunition being required to shoot down a heavy bomber is often quoted to show just how wasteful and ineffective antiaircraft fire really was. But that number is misleading. While it fits well into the Allied narrative of how the strategic bombing campaign robbed the German army of valuable munitions, it was only partially true.  Indeed when you compare these numbers to the more effective 128mm AA gun the numbers are intriguing. In 1944 the number of 128mm rounds per aircraft shootdown was 3,000, less than one-fifth the number expended by its 88mm counterpart. This doesn’t take into account the number of aircraft that were severely damaged by flak.”

Where was best defended by flak in WW2?

“I would point to the Luftwaffe flak defenses of the Ruhr, their larger cities like Berlin and their oil refineries. Their light and medium flak over the battlefield was also highly effective and took a great toll on Allied fighter bombers. Allied AA defenses were also effective, one example being the battles against the V-1 flying bombs and the fact that they chose to defend Antwerp against the V-1 using AA guns along is testament to their effectiveness.

7. What was the best AAA system of WW2?

The obvious choice would be the Luftwaffe’s AA defenses, but I would point to the US Navy’s development of the VT fuse or radar equipped proximity fuse. Built around a miniature radio transmitter and receiver, the VT fuse overcame the major disadvantage of the “time” and “contact” fuses and was capable of detecting its target and detonating within 75 feet. It was a game changer and fortunately for the US Navy they had it when the kamikaze appeared. Indeed, even before the kamikaze appeared the US Navy made major improvement to their ships AA defenses with better radar direction, improved AA directors and gunsights and most importantly, more guns. In 1944 the battleship USS Missouri bristled with twenty 5 inch, eighty 40mm and over forty-nine 20mm cannon.

What were the big innovations in AAA in WW2? 

“It was the invention of the VT radar proximity fuse. If the Luftwaffe had this shell the Allied bombing campaign would have been far more costly, or stopped altogether. Mention has to be made of the development of gun laying radar. This allowed for aiming at night and in bad weather.”

Which nation was best at using AAA and why? 

“I would say the Germans and the Allies had guns and systems that were equal in effectiveness. The allies had the edge with the VT fuse. The Japanese did not develop a robust AA defensive system. They lacked the guns, effective radar, and the cooperation between the Army and Navy was terrible. They never pooled their resources, instead each would go their own way, often siting individual radars in the same place.”

Tell me a myth about flak

“Two myths about flak: one it was not very effective, from an Allied point of view, and second the Allied bombing campaign against Germany created a ‘second front’ siphoning off thousands of men to man the guns and robbing the German army of valuable men. This was only partially true. You have to remember that the Luftwaffe flak arm played a dual role. Luftwaffe flak batteries could be assigned to the army at any time and thousands were. Shortly after D-Day the Luftwaffe transferred 140 heavy batteries and 50 light flak batteries to Normandy. This process continued for the last 10 months of the war, robbing German cities of vital flak defences. As the war progress and the manpower shortage increased thousands of able-bodied flak men were transferred to the army. In their place were hastily trained factory workers, schoolboys, prisoners of war, older men not fit for combat and by the end of the war they introduced the first batteries manned by women for the defence of Berlin. By April 1945 44 percent of the flak arm was made up of people unqualified for combat, foreign nationals or prisoners of war.”

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Which aircraft type could withstand the most damage? Was armour speed a better defence from flak?

“All aircraft were susceptible to flak. There were a few that were specifically armoured like the Russian Il-2  and German Hs 129 ground attack aircraft to withstand light flak hits. Most Allied bombers and fighters were armoured against fighter attack, but not flak. Speed was a factor, and most fighter pilots knew that when strafing a target you never made a second pass.”

When did radar guided AAA arrive? 

“At the beginning of the war, the first British gun-laying Mark I (GL I) radars entered service with several AA batteries. In many ways the term gun-laying was a misnomer when applied to the GL I. It was more of a gun-assisting radar with limited capabilities. Although it gave accurate ranges, it could not produce good azimuth indications or elevation figures.

By the summer of 1941 the Germans introduced their Wurzburg gun laying radar.”

Why should people buy your book?

“The story of flak in World War II is one of those forgotten stories of World War II. There was a reason the official histories downplayed the effectiveness of German flak. It took away from the narrative of how successful the Allied bombing campaign was and the heavy price they paid.

Thousands of aircraft were shot down, and tens of thousands were damaged, not to mention the horrendous cost in lives and those wounded. Flak in World War II takes the reader from the invasion of Poland in 1939 right to the last Japanese aircraft shot down by AA fire in August 1945. It examines heavy flak defences, flak over the battlefield, the failure of ship AA defences early in the war; specifically the Bismarck and the sinking of the Prince of Wales and Repulse in 1941, AA defences against the world’s first cruise missile (V-1), right up to the human guided missile that was the kamikaze in the Pacific.”

What led you to write about Flak? 

“I was inspired after reading Edward B. Westermann’s book Flak: German Anti-Aircraft Defenses 1914-1945. His in-depth and comprehensive study of German flak defences clearly showed how effective they really were. This led me to thinking of how AA guns and defences played a role in the air war over Europe and the Pacific. Most, if not all, of the histories deal with the great air battles strictly in terms of aircraft vs. aircraft; the great fighter aces and how many bombers were shot down by Spitfires, Bf 109s, Fw 190s and Me 110 and Ju 88 night-fighters. And when I started digging deeper, the number of aircraft shot down by flak was astonishing. German flak defenses were responsible for more than half of all Allied aircraft losses. Allied AA guns were equally effective. The Marine heavy AA guns on Guadalcanal, for example, in 1942 forced Japanese to bombers to fly higher reducing their accuracy to a great extent, but you never hear or read about it. The story mostly centres around the fighter defence and how the F4F Wildcat matched up against the vaunted A6M Zero-sen. Both AA guns and the defending fighters played a role in the defence of Guadalcanal. It not just one or the other.”