CH Hydrographic Survey Standards & Quality Control 2

Question 1

Under IHO S-44 Order 1a, what is the maximum allowable Total Horizontal Uncertainty (THU) at the 95% confidence level for feature detection?

Accepted Answer

2 m + 5% of depth

Answer

IHO S-44 Order 1a specifies a THU of 2 m + 5% of depth at the 95% confidence level for feature detection.

Question 2

Which statistical measure is used to combine random and systematic error components in Total Propagated Uncertainty (TPU) calculations?

Accepted Answer

Root Sum of Squares (RSS)

Answer

Total Propagated Uncertainty combines error components using Root Sum of Squares (RSS) to produce a single uncertainty estimate.

Question 3

A bathymetric survey detects a cross-line check depth that differs from the main scheme depth by more than the allowable TVU. What is the correct action?

Accepted Answer

Re-survey the area with the main scheme to investigate

Answer

When cross-line discrepancies exceed allowable TVU, the area must be re-surveyed with the main scheme to investigate the source of the error.

Question 4

What percentage of the survey area must typically be covered by cross (check) lines in a standard hydrographic survey?

Accepted Answer

10%

Answer

Approximately 10% of the survey area is typically covered by cross lines to provide independent quality control checks.

Question 5

In NOAA survey specifications, what is the primary purpose of the 'Danger to Navigation' (DTN) protocol?

Accepted Answer

To immediately report newly discovered hazards to mariners

Answer

The DTN protocol ensures that newly discovered navigation hazards are immediately communicated to mariners via Notices to Mariners or Local Notices.

(CH) Certified Hydrographer Practice Test

(CH) Certified Hydrographer Practice Test

CH Hydrographic Survey Standards & Quality Control 2