The bombardment missions of the 8th Army Air Forces in World War II were well planned with targets selected and the route determined in advance, and weather conditions checked at the air bases in England, along the route, and the area of the target. Probable flak zones were identified, too.
The bombs were loaded, the planes were readied – repaired and fueled – by the ground crews. The air crews were awakened, fed, briefed, and dressed in flight gear, armed with maps, ammunition, oxygen, and a prayer from the Group’s clergymen.
Pilots, navigators, bombardiers, and gunners manned their positions and prepared for their day’s work. Regardless of their position or job on the crew, the goal of each man was the same, to drop their B-17’s bombs on the day’s chosen target.
The navigator’s job was to plot the course both to the target and back to base. The gunners’ jobs were to protect the plane from enemy aircraft so that it would make it to the target. The bombardier’s job was to release the bombs at exactly the right moment for them to strike the target as accurately as possible.
The bombardier worked closely with the pilot to insure an accurate bomb drop, making their positions much more involved in the accuracy of the bomb release than the remainder of the crew, but all of the crew members had roles to play in getting those bombs to their destination.
The bombing mission could take many hours, depending how deep into Germany the formation would travel to arrive at the target, and as many hours for the return trip home. But the most critical period of the mission was that of the bomb run, which began at the Initial Point and concluded with Bombs Away, and was generally measured in minutes, a fraction of the length of the mission.
The steps taken between the B-17 pilot and bombardier depended upon several factors, including whether they were manning a lead aircraft. The lead aircraft carried the lead bombardiers and these officers determined the exact time and location of the bomb release. Other bombardiers of the formation who were following the lead dropped their bombs with the lead rather than calculating their own time and place to drop their bombs.
The 303rd Bomb Group’s website explains in great detail the factors that had to be controlled for the bomb run to be successful and the bomb release to be accurate. I will only summarize here and the 303rd’s information can be reviewed for the detail.
To assist the Bombardier in doing his job successfully, the Pilot had to,
- Place the aircraft in the proper position to arrive at a point on a circle about the target from which the bombs could be released to hit the target.
- Control the altitude of the aircraft, which partially determined the time of the bomb fall from time of release to the moment of impact.
- Control the true airspeed, the measure of the speed of the aircraft through the air.
- Control the groundspeed, the speed of the airplane in relation to the earth’s surface, while maintaining the correct altitude and constant airspeed.
The Bombardier, in determining the time and place of the bomb drop, controlled,
- Bomb ballistics, by consulting bomb ballistics tables to account for type of bomb.
- Trail, the horizontal distance the bomb was behind the airplane at the instant of impact, obtained from bombing tables and set in the bomb sight. However, trail was affected by the altitude and airspeed, which were controlled by the pilot, and by bomb ballistics and air density.
- Drift, which was determined by the direction and velocity of the wind, and was set on the bombsight by the bombardier.
Prior to the bomb run, and even before takeoff, the pilot worked to set up the correct conditions to determine the proper point of bomb release.
- Prior to takeoff, the pilot checked the aircraft’s flight instruments – the altimeter, airspeed indicator, free air temperature gauge, and all gyro instruments – for accuracy.
- The pilot checked the C-1 automatic pilot for proper function.
- The pilot checked the PDI (Pilot Direction or Directional Indicator), which was an instrument the bombardier used to indicate heading changes to the pilot in order to direct him to the proper location for the bomb drop.
- If the bomb run was to be made on auto pilot, the pilot adjusted the auto pilot before reaching the target area under the same conditions that would exist over the target, and would continue to adjust due to changes in load due to gas consumption, before reaching the target.
- The pilot adjusted the turn compensation knobs of the auto pilot to coordinate with the bombardier making turns to it.
- The pilot adjusted the PDI using coordinated smooth turns and trimmed the aircraft so that the aircraft flew practically hands off with the bomb bay doors open.
- The pilot and bombardier considered the effect of evasive action before reaching the initial point of the bomb run.
- The (lead) bombardier selected the initial point onto the as-briefed heading for the beginning point of the bomb run.
- Depending on whether the bombardier is the lead bombardier, either he or the pilot directed the aircraft to the exact position of the initial point and was on the as-briefed heading.
Even though the longest possible bomb run seldom exceeded three minutes, during the crucial portion of the bomb run, from initial point until bombs away, evasive action was discontinued, and flak and fighter opposition were ignored if bombs were to hit the target.
Either before or during the bomb run,
- At the initial point of the bomb run, the (lead) bombardier took over the direction of flight by engaging a clutch on his bomb sight. He made adjustments on the sight to hold the sight’s hairline on target, automatically guiding the aircraft to the required course and target. He gave directions to the pilot for the operation of the bomb run.
- The bombardier asked the pilot for a level, which means the pilot accurately leveled the aircraft using his instruments, and held that level until the bombs were dropped. Just one degree of tilt before or at the time of the bomb drop could cause an error of around 440 feet at an altitude of 20,000 feet.
- In the case of a manually flown mission using the PDI (rather than using the auto pilot), the bombardier zeroed the PDI while the aircraft was lined up on a direct course with the target. The pilot then adjusted the stick and rudder to hold the PDI on zero.
- The pilot maintained the selected altitude and airspeed as closely as possible while the bombardier set his course. Again, minor changes could greatly increase the error in the bombs reaching their target.
At the carefully calculated moment, the bombardier released the bombs on the target – Bombs Away!
After bomb release,
- Evasive action could be continued if it had to be discontinued during the bomb run.
- The pilot could continue to fly the aircraft on auto pilot or choose to fly manually.
- The aircraft and the formation headed for home.
Sources and Further Reading
Carlsbad Army Airfield public Facebook page
Facebook post from Carlsbad Army Airfield, Bombardier Training
303rd Bomb Group: Duties and Responsibilities of the Bombardier
B-17 Flying Fortress Queen of the Skies, Crew Positions, Bombardier
© Cindy Farrar Bryan and The Arrowhead Club, 2023
I had no idea that planes had auto pilot in the 1940s. And second, I can’t imagine being on a bomb run and ignoring counterattacks or flak happening around you! Nerves of steel, I guess…
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And your dad had a front row seat up in the Plexiglas nose to see what they were flying into. I can’t imagine what that felt like.
The effort that went into planning a mission let alone the dropping of the actual bombs was just incredible. All those people working behind the scenes to establish weather, routing, AA defences etc etc was enormous.
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