The phrase "are in commission" implies that something is actively working or functioning. Antonyms of this phrase could include "out of commission," which means something is broken or not working properly. Another antonym could be "dormant," which means something is not active or functioning at the present time. "Idle" is yet another antonym, implying that something is not currently at work or in use. In contrast, "active" would be a synonym for "are in commission" as it refers to the same concept of something being actively working or in use.