“working aloft chit” signifies that all equipment is in a nonradiating  status  (the  equipment  is  not  moving).  The person  who  signs  the  chit  should  ensure  that  no  RF danger exists in areas where personnel are working. Nearby ships or parked aircraft are another source of RF energy that must be considered when checking work areas for safety. Combustible materials can be ignited  and  cause  severe  fires  from  arcs  or  heat generated  by  RF  energy.  RF  radiation  can  detonate ordnance devices by inducing currents in the internal wiring of the device or in the external test equipment, or leads connected to the device. You should always obey RF radiation warning signs and keep a safe distance from radiating antennas. The six types of warning signs for RF radiation hazard are shown in figure 2-40. RF  BURNS Close or direct contact with RF transmission lines or antennas may result in RF burns. These are usually deep,  penetrating,  third-degree  burns.  To  heal  properly, these burns must heal from the inside to the skin surface. To prevent infection, you must give proper medical attention  to  all  RF  burns,  including  the  small  “pinhole” burns. Petrolatum gauze can be used to cover burns temporarily before the injured person reports to medical facilities for further treatment. DIELECTRIC HEATING Dielectric heating is the heating of an insulating material  by  placing  it  in  a  high  frequency  electric  field. The heat results from internal losses during the rapid reversal of polarization of molecules in the dielectric material. In the case of a person in an RF field, the body acts as a dielectric, If the power in the RF field exceeds 10 milliwatts per centimeter, a person in that field will have noticeable rise in body temperature. The eyes are highly  susceptible  to  dielectric  heating.  For  this  reason, you should not look directly into devices radiating RF energy. The vital organs of the body are also susceptible to dielectric heating. For your own safety, you must not stand directly in the path of RF radiating devices. PRECAUTIONS WHEN WORKING ALOFT Prior to going aloft, you must follow all NAVOSH and local requirements such as wearing a harness and a hard hat. You must have a safety observer and meet all other   requirements. When radio or radar antennas are energized by transmitters,  you  must  not  go  aloft  unless  advance  tests show that little or no danger exists. A casualty can occur from even a small spark drawn from a charged piece of metal or rigging. Although the spark itself may be harmless, the “surprise” may cause you to let go of the antenna involuntarily, and you may fall. There is also a shock hazard if nearby antennas are energized. Rotating antennas also may cause you to fall when your   are   working   aloft.   Motor   safety   switches controlling  the  motion  of  rotating  antennas  must  be tagged and locked opened before you go aloft near such antennas. When working near a stack, you should draw and wear the recommended oxygen breathing apparatus. Among other toxic substances, stack gas contains carbon monoxide. Carbon monoxide is too unstable to build up to a high concentration in the open, but prolonged  exposure  to  even  small  quantities  is dangerous. SUMMARY Naval communications using satellite and various antennas types must always be ready to shift from peacetime to wartime requirements. To this end, the diversity of fleet communication operations has given the  Navy  an  expanded  capability  to  meet  ever- increasing   command,   control,   and   support requirements by use of satellites and assorted antennas. Additionally,  this  variety  of  communications technology has increased the requirements for greater proficiency   from   all   operating   personnel.   As   a Radioman,  you  will  be  tasked  with  higher  levels  of performance in an increasingly technical Navy. 2-31