NOTE: Whenever possible, the RFR burn source
should be replaced with a nonmetallic substitute or
relocated or reoriented to eliminate the hazard before
resorting to a type 3 sign for personnel protection.
A type 3 sign should be installed on the RFR burn
source or in the immediate vicinity where it can be seen
easily. When used on cargo handling running rigging,
type 3 signs should be mounted on the hook insulator.
Personnel should be warned to not touch the
wire/rigging above the insulator. More than one type 3
sign should be installed on larger burn sources that can
be approached from multiple directions.
Type 4WARNING RADIO FREQUENCY
HAZARD . . . FUELING OPERATIONS
The type 4 sign advises of the hazards of
electromagnetic radiation to fuels (HERF). These
signs are normally used only on ships that carry
aviation gasoline (AVGAS) or automotive gasoline
(MOGAS). Marine diesel fuel and JP-5 jet fuel are not
considered to have a HERF problem and require no
special electromagnetic safety precautions during
fueling. Most naval ships do not carry gasoline. An
exception to this is amphibious ships carrying
gasoline-powered landing vehicles. Aboard ships that
carry AVGAS or MOGAS, personnel should observe
the following precautions during fueling or fuel
1. Secure all transmitting antennas located within
the quadrant of the ship in which fueling is being
2. Ensure that RADHAZ cutouts for microwave
radiators are not overridden during fueling,
which could result in the illumination of the
3. Do not energize any radar or communications
transmitter on any aircraft or vehicle.
4. Do not make or break any electrical, static
ground wire, or tie down connection, or any
metallic connection to the aircraft or motor
vehicle while it is being fueled. Make the
connections before the fueling commences.
Break them afterward.
Type 5WARNING RADIO FREQUENCY
HAZARD (SPECIAL CONDITION)
The type 5 sign has a blank area for filling in
special safety precautions. Its purpose is to advise
personnel of procedures to follow when other
RADHAZ warning signs are not appropriate.
Examples of directions that can be filled in on a type 5
Inform OOD before placing system in radiate.
In manual mode, do not depress below horizon
between ______ and _______ degrees relative.
Ensure temporary exclusion barriers are in
place before radiating.
Do not stop antenna between _______ and
_______ degrees while radiating.
A type 5 sign is normally installed below decks in a
system operating room. It should be installed in the
vicinity of controls such as a radiate switch or antenna
control switch, where the person operating the gear in
normal operation can see it. When mounted on system
cabinets or control panels, RADHAZ signs should not
obscure switch labels, meters, indicators or nameplate
Type 6WARNING RADIO FREQUENCY
HAZARD . . . HAZARD TO ORDNANCE
T h e t y p e 6 s i g n a d v i s e s o f h a z a r d s o f
electromagnetic radiation to ordnance (HERO).
NAVSEA OP 3565 explains the purpose of HERO
signs and where to place them.
ROTATION HAZARD WARNING
Rotating directors present a serious danger to
personnel near them. To guard against this hazard, be
sure the topside area near the directors is cleared of all
personnel before you energize a director. DANGER
ROTATION HAZARD warnings should also be
posted or painted in conspicuous places to alert unwary
What OPNAV instruction gives the OOD
guidance for the Working Aloft Check Sheet?
What size RADHAZ signs should be used on
What type of RADHAZ warning signs should be
used when other RADHAZ signs are NOT
OTHER RADAR HAZARDS
The hazards we discussed above occur primarily
on the exterior of the ship. We now need to discuss