Marines with Marine Wing Headquarters Squadron (MWHS) 3 conduct a land navigation course during their Command Post Exercise aboard Marine Corps Air Station Miramar, California, Jan. 19. Marines with MWHS-3 participated in a three-day, two-night CPX designed to instill and improve field and tactical skills of the Headquarter Marines, Jan. 19-21. - Marines with Marine Wing Headquarters Squadron (MWHS) 3 conduct a land navigation course during their Command Post Exercise aboard Marine Corps Air Station Miramar, California, Jan. 19. Marines with MWHS-3 participated in a three-day, two-night CPX designed to instill and improve field and tactical skills of the Headquarter Marines, Jan. 19-21.