Complex sentence: In the U.S. Navy, airman is the enlisted rank that corresponds to the pay grade of E- 3 in the Navy's aviation field, but it is just below the rank of petty officer third class, pay grade E- 4.
Split into simpler sentences: In the U.S. Navy, airman is the enlisted rank that corresponds to the pay grade of E- 3 in the Navy's aviation field. Airman pay grade, but it is just below the rank of petty officer third class, pay grade E- 4.