Passing close to a single, strongly-reflective target (such as a steel navigation buoy or small craft with a good radar reflector), you notice a faint arc or ring of additional weak echoes around it, all at approximately the same range as the true target but spread across a range of bearings. Your examiner asks you to explain this.

A. Side-lobe echoes are caused by energy that leaks out of the antenna in directions OUTSIDE the main, narrow transmitted beam — every radar antenna radiates some energy in minor side lobes as well as the main lobe, by the nature of the antenna design. If a target is close enough and reflective enough, even the relatively weak side-lobe energy can produce a detectable return. Because the side lobes point in a spread of directions around the main lobe, the resulting false echoes appear at approximately the SAME RANGE as the true target but at a SPREAD of BEARINGS either side of the true bearing, typically forming an arc or partial ring pattern on the display, most noticeable with strong, close targets.

B. Side-lobe echoes are caused by the pulse bouncing back and forth between own ship and the target multiple times, producing echoes at multiples of the true range on the same bearing — this describes multiple echoes, not side-lobe echoes.

C. Side-lobe echoes only occur in rain and are eliminated entirely by the anti-clutter rain (FTC) control, with no relationship to antenna design or target strength.

D. Side-lobe echoes appear at a completely different range from the true target, never at the same range, which is what distinguishes them from all other false-echo types.

A. Nothing — a test lift can proceed immediately after repairs

B. Testing should wait until cargo operations begin

C. The area within the grab's swing radius should be cleared of personnel before the lift

D. Only the crane operator needs to be aware the lift is happening

A. Who must remain clear of the exclusion zone while the lift takes place

B. The lunch schedule for the deck team

C. Only the weather forecast for the next watch

D. The cargo manifest for the next port