How aircraft role letters shaped squadron codes

The system used Z for lighter-than-air types and V for heavier-than-air aircraft, followed by mission letters such as F for fighting, O for observation, S for scouting, P for patrol, and T for torpedo work. The British TSR description of the Fairey Swordfish shows how another navy could classify the same multi-role aircraft differently. Secondary designations introduced in 1934 produced increasingly complex combinations such as VBF, VOS, VPB, VPT, VSSB, VSSO, and VTB. Ernest J. King, who succeeded Moffett as chief of the Bureau of Aeronautics, still had to keep the code current and legible enough that officers could identify a squadron's purpose without asking him. Because aircraft and squadrons could encode roles differently, a label that looked precise could still mislead a reader about what the unit actually flew or did.