There's A Good Reason Why US Navy Ships Use Onboard Calibration Labs

Modern United States Navy ships are among the most impressive vessels ever to sail the seas, but it's not necessarily easy to appreciate the technology and capabilities of aircraft carriers like the USS Gerald R. Ford. Some features, be it a carrier's nuclear power plant, catapult mechanism, or advanced weaponry, are obvious, but these vessels also have smaller, lesser-known features that can be equally important.

One of these areas is the onboard Metrology and Calibration Laboratory, more commonly known as METCAL. Why, exactly, would you need a laboratory on board a ship like an aircraft carrier, whose primary mission is launching warplanes? It's because the METCAL performs the vital, yet under-appreciated task of keeping the ship's equipment and associated instruments calibrated and accurate. 

Given the military's overall emphasis on precision, correct calibration of equipment and instruments is critical for safety and fighting effectiveness. Many of these calibration jobs are quite involved, too. While some of this work can be done in traditional land-based laboratories, larger ships that spend extended periods at sea far from their home ports rely on their onboard METCAL centers and dedicated crews for these tasks. The METCAL's smaller, yet consequential role in a carrier's daily operations is just one more reason why these ships are often likened to floating cities.

The Navy founded its METCAL program in the 1950s, after Navy employee Jerry Hayes discovered that incorrectly calibrated instruments were resulting in unreliable missile tests. The result was the establishment of the Navy Metrology Engineering Center. Note that while we're focusing on the Navy, metrology and calibration labs can be found throughout the United States Military.

Metrology is broadly defined as the science of measurement, which plays a crucial role in many scientific fields. The Navy's primary metrology department operates as part of the Naval Special Warfare Command (NSWC) Corona Division. Only certain Navy ships have their own METCAL department, usually larger ships like aircraft carriers and the Navy's similarly impressive amphibious assault ships like the USS America. 

Smaller vessels can have their calibration handled by regional shore-based METCAL centers, but not the larger carriers and amphibious ships. Not only are these ships filled with equipment that needs calibrating, but they also operate aircraft that similarly require calibration. Additionally, the amount of time these larger vessels spend away from port means that having an onboard METCAL lab to handle calibration tasks is vital for self-sufficiency.

So how much work does a METCAL lab do? In 2007, the Navy METCAL was performing over 525,000 calibrations per year across its hundreds of land- and sea-based labs, and that number is likely higher today. There are also over 5,000 calibration procedures for the various types of equipment the Navy uses. 

On board the carrier USS Harry S. Truman, which was rated best in the Navy for its METCAL performance in 2021, there are about 12,000 pieces of equipment in need of regular calibration, with the ship's lab handling around 550 calibration jobs per month. These include night vision goggles, with METCAL crew members tasked with ensuring Navy pilots' goggles are set to the correct sensitivity.

Even while at port, a ship's METCAL department can play a crucial role. In 2024, while the amphibious assault ship USS Essex was drydocked for repair and maintenance, the ship's METCAL lab successfully calibrated and maintained the ship's firefighting system, in a demanding job that would normally have been contracted out at great expense. For this achievement, Essex's lab and its 13 technicians were recognized with a Navy Self-Sufficiency Award.