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"Combat Box": Bomber Formations

Formations were designed to protect heavy bombers against fighter attack and to concentrate the bomb pattern on the target.  These formations evolved over time to counter enemy tactics and to adjust for the increasing numbers of heavy bombers involved.


B-17 formation during the mission against the Messerschmitt Bf 110 assembly plant in Brunswick, Germany on January 11, 1944.  A single burst of flak is visible in the middle of the image.


With bases close together and hundreds of bombers in the air, forming up was a time-consuming challenge.  This illustration shows the designated locations for each bomber group to form up in overcast weather.



Collisions within formations were not uncommon.  Here, two B-17s flying through overcast skies collided while returning from a mission—all crewmen aboard both aircraft were killed.




With hundreds of aircraft and thousands of Airmen in the air on a mission, communication within and between aircraft could be challenging.  Of particular importance was communication among the crew to call out the direction of attacking fighters.  Many different systems and methods permitted the exchange of information.


Headset and Throat Microphone 

Some crewmen wore a headset over a “50-mission crush cap”—others wore flight helmets that contained headphones.  Early crews wore throat microphones, while later Airmen had microphones mounted in their oxygen masks.



            Radio Control Box

A box mounted at crew stations controlled communication:

1. COMP: Radio compass receiver (for navigation)

2. LIAISON: To communicate with other aircraft in the formation with VHF (Very High Frequency).

3. COMMAND: For air-to-ground communication in MF (Medium Frequency).

4. INTER: To communicate within the aircraft.

5. CALL: Alerted crewman within the aircraft to switch to INTER.  When this was used, it canceled out all other communication.



Radio Operator Telegraph Key

The radio operator’s equipment included a telegraph key to send Morse code messages over long distance.  Morse code represents letters with combinations of long and short signals (“dots” and “dashes”).



Signal Lamp

Also called Aldis lamps, signal lamps permitted bomber crews to communicate between aircraft using Morse code and without using the radio.  Color filters, like those on display, could also be attached for prearranged signals.



M8 Flare Gun

Different colored flares could be fired from the aircraft to indicate various prearranged signals, such as declaring an emergency landing, notifying there are wounded on board, or to identify the aircraft as friendly.


Recognition instructions for November 4-5, 1942, showing the correct flare cartridge colors, what Morse code letters to flash, and what color filter to be used in a signal lamp.




Life at 25,000 Feet

US Army Air Forces heavy bombers in Europe typically flew at 20,000 to 30,000 feet to reduce vulnerability to antiaircraft fire.  Flying many hours at high altitude in unpressurized aircraft, however, created other hazards for the crews.





At 25,000 feet, a crewman without supplemental oxygen passed out in 3-5 minutes, followed by death soon after.  At high altitude, crewmen needed supplemental oxygen at all times—malfunctions, such as blocked hoses and frozen oxygen masks, killed some Airmen.









Oxygen Mask

The mask on display was a typical type used in 1944, which by then also contained an integral microphone. 


Oxygen Regulator

Each crew station contained a regulator that connected the mask to the aircraft’s oxygen system.



Walkaround Bottle

Crewmen plugged their oxygen masks into a “walkaround bottle” to carry with them when they moved around the aircraft.  These bottles contained about 12 minutes of oxygen.




Bailout Bottle

                                          A bailout bottle, which was attached to the parachute harness or strapped to a leg, provided enough oxygen to drift down to a                                                                  safe altitude.




Aircraft Oxygen Tank

A heavy bomber carried several oxygen tanks to supply the aircraft’s system.  If damaged, the pressurized oxygen released created a serious fire hazard.











Fighting the Cold

With temperatures as low as 50 degrees below zero Fahrenheit at high altitude, frostbite from the bitter cold was a constant danger.  The B-17’s heating system kept the cockpit warm, but it was not effective at other crew stations.  The B-24’s heating system was no better.


Early Bomber Crew Clothing

Early bomber crewmen wore thick sheep shearling clothing to fend off the crippling cold. 


“Blue Bunny” Electrically-Heated Suit

Some crewmen wore electrically-heated undergarments and gloves.  They had internal wires that functioned like those in a heating pad.  This early F-1 suit was nicknamed the “Blue Bunny” for its distinctive color.  The single-circuit F-1 was notoriously unreliable.  The internal wires often broke while in use, shocking (and sometimes burning) the wearer and leaving them without heat.


Heater Control

Electric suits plugged into a heater control box located at each crew station.


Late War Bomber Crew Clothing

Bomber crew clothing improved dramatically during the war.  Lighter-weight, alpaca-lined clothing and improved electrically-heated undergarments provided more comfort and greater mobility.

Late war Eighth Air Force B-17 crew.

Heat generated from the B-17’s left inboard engine was used to send warm air to the crew stations in the middle and forward part of the aircraft.





Related Fact Sheets

The Memphis Belle: American Icon and 25th Mission

Memphis Belle Crew

The “Memphis Belle” and Nose Art

26th Mission: War Bond Tour

Memphis Belle: A Story of a Flying Fortress”

Heavy Bomber “Firsts”

Combat Aircraft to Museum Artifact

Crippling the Nazi War Machine: USAAF Strategic Bombing in Europe

Enabling Technologies

Key Leaders

Early Operations (1942 to mid-1943) - Eighth Air Force in England

Ninth/Twelfth Air Forces in the Mediterranean

Combat Box/Communication and Life at 25K

Keeping them Flying: Mechanics and Armorers

Combined Bomber Offensive: Summer 1943 to Victory

Bigger Raids, Bigger Losses, and Crisis

Deadly Skies over Europe (Luftwaffe defense)

Bomber Crew Protection

Operation Tidalwave (Ploesti, 1 Aug 43)

Regensburg/Schweinfurt (17 Aug 43)

Black Thursday/Schweinfurt (14 Oct 43)

Fifteenth Air Force (created Sep 43)


Women’s Army Corps

Fighter Escort: Little Friends

Big Week (20-25 Feb 44)

Target Berlin

Operation Frantic: Shuttle Raids to the Soviet Union

Blind Bombing

D-Day Support

Strategic Bombing Victorious




Return to the B-17F Memphis Belle Fact Sheet

Return to the WWII Gallery list