Reviewing AVA Reports

If you’re responsible for reviewing 7054 reports from the field, or you want to understand your reports better, this is for you. Many reports in the future will be coming from the AV Assistant (AVA) app that runs on mobile devices (currently only iPhones and iPads).

Have you wondered exactly what AVA does and what all the lines AVA adds to the report and photos mean? And why certain fields in the 7054 report can’t be changed? Let’s find out.

Locked Fields

First, some fields are locked on the PDF and can’t be changed. Why? The reason is to preserve data integrity and establish confidence in the report for Auxiliary and USCG reviewers.

The following fields are locked by AVA and can’t be changed in post-editing. Any changes to these fields might identify another aid, no aid, or result in mismatches, causing confusion and casting doubt on the report. Unfortunately, due to the nature of Adobe protection, you can’t select the contents of these fields for cut and paste either.

• Date/Time Observed – when the report was started (date & time) at the aid. Reviewers need to know the date and time you were at the aid since another report could come in on the same aid from a different source.
• LLNR, Aid Number (aka Aid UID) – these are the primary identifiers and they identify the aid in the Light List and in the CG database.
• Latitude/Longitude (aka Fix Latitude/Longitude) – this is the position fix taken by AVA at the site of the aid when the report was made.
• Time Taken (aka Fix Time) – the time of the position fix.
• PATON’s Name (aka Aid Name) – this also identifies the aid, secondary to its LLNR or UID.
• QC Check – this is the specific GPS error measure which can be HA, EPE, HDOP, etc. In this case, it is HA, or Horizontal Accuracy.
• QC Reading (aka Fix Horizontal Accuracy) – the HA is read directly from the device or an external Bluetooth GPS.
• Comment block on page 1 – AVA uses this space for its own comments

At present, all other fields on page 1 of the 7054 are unlocked for post-survey editing. Why are they editable? For two reasons – it can be difficult, due to motion, bright sunshine, inclement weather, sea state, or time pressure, to finish a report in full on the spot. Second, the AV may notice something in the photos or in review at home that needs to be added or commented on.

The goal, in spite of these difficulties, is to try to fully complete an AVA report on site, with no need to do any post-editing. That only comes with constant practice.

Page 1 Comments

Let’s discuss the page 1 comments – an excerpt from a report is shown here.

Light List AP – this is the aid’s Assigned Position (AP) in the Light List or USAIMS database. Listing this saves the reviewer the trouble of looking it up.

PT used is the Positioning Tolerance for the aid. Fixed aids use 60 ft (20 yards) and floating aids use 120 ft (40 yards), per the Office of Navigation Systems (CG-NAV) for AVA use (PATONs only). This figure is used in computing whether an aid may be off-station.

Fix is within – AVA computes the accuracy of its fix using three factors – 2DRMS, Closest Approach (CA), and Speed Error (SE). The calculation is broken down on the line to make it clear to reviewers.

(15.6 * 2.4022) is HA as provided by the GPS (50% confidence) times 2.4022 to arrive at the 2DRMS figure (95% confidence) used by the USCG.

0.0 means the Closest Approach used was contact with the aid.

0.0 means the position fix was taken at a dead stop relative to the aid.

Under most circumstances, around 39 ft is going to be the best fix achievable by AVA (even with a more accurate external GPS, due to iOS software limitations).

Observed distance from Position Fix to AP is how far the aid is from its assigned position. AVA is able to calculate this distance immediately after the position fix is taken.

GPS is – identifies the device used, or if an external GPS is used, inserts the description of the external device from Settings.

LL, LNM, USAIMS are the databases used by AVA, followed by their published dates, so reviewers know exactly which revision was used.

Files: shows the identifier used by all files in the report (with different extensions), so they can be located if the files are stored separately.

Page 2 Comments

Comments by the Aids Verifier (AV) go on page 2 and those comments are editable. AVA lists the selections made by the AV here as well. In many cases, no further comment is needed, particularly if a good photo illustrates the condition.

Here is one example of comments inserted by AVA. While the formatting might look a bit odd since AVA concatenates the selections, the meaning is clear enough and the photos should resolve any questions. This section can be edited if the AV feels the need to explain further.

Screenshot

This is a new feature in AVA for 2023. A screenshot is taken when a report is started (tapping on the document icon in the aid information block).

This screenshot shows what is on the AVA screen at the instant the report was started. Two circles are visible at the center.

The circle with the solid outline is the AV’s present location, calculated by AVA as described above but Closest Approach is not included (=0) because the position fix has not yet been taken. The actual real location can be anywhere inside this solid outline blue circle due to GPS errors – see Anatomy of a GPS Fix for more detail.

The circle with the dashed outline is the Positioning Tolerance (PT) circle around the aid, using 60 feet for a fixed aid or 120 feet for a floating aid. The aid’s real location may be anywhere inside this dashed outline blue circle.

For reviewers, the screenshot simply establishes that the AV was in the vicinity of the aid when the report was started. Exceptions can arise where the aid’s assigned position (AP) is so far off, the PT circle is not visible on the screen (we have found aids miles away on land).

Since this diagram is so useful in showing off-station aids, I now recommend users come up very close to the aid (contact or 1-5 feet) before starting a report and then take a Position Fix (PF) immediately after. Photos will then need to be taken upon departure. If this practice is followed, then the screenshot is a visual confirmation of off-station (or not). Overlapping circles means the AV is within the aid’s positioning tolerance and it is not off-station. Separate circles mean there is no location where the AV could be within the aid’s positioning tolerance and therefore it could be off-station (but the AV makes the decision as to whether to report it off-station). See Anatomy of a GPS Fix – Part 2 for more detail.

Photos

AVA also annotates any photos taken with additional information directly on the photo. Let’s look at one.

• Line 1 identifies the file name of the report files – currently, a .pdf and .kml (for Google Earth) are generated by AVA for every report.
• Line 2 is the aid name.
• Line 3 is the position fix (latitude and longitude).
• Line 4 is the camera’s position (latitude and longitude) as well as the compass direction the camera was facing, the HA reading, and the age (seconds since the last time the GPS was read) of the reading.
• Line 5 shows the distance from the camera to the position fix.
• Line 6 shows the distance from the camera to the assigned position of the aid.
• Line 7 shows the max leaning angle of the aid. This can be changed in AVA Settings for your local district requirements. The photo shows the actual lean when the camera is rotated to match the aid, as in the following photo (see the red 28° in the inset, center right).

Photos should show the number of the aid if it is present – this is a safeguard against making a report on the wrong aid.

Google Earth

Lastly, AVA produces a .kml file for Google Earth. If you have Google Earth installed, you can open this file directly. Google Earth is an excellent tool for reviewing the physical location of an aid. In some cases, you can see the actual aid in the satellite image (often as a shadow).

What to Look For

Here are some suggestions for reviewing an AVA report – aside from the usual 7054 checking.

• Check the screenshot to confirm the AV was in the vicinity of the aid (this will not be the case if the aid’s AP is sufficiently far away – like miles inland)
• Freshness – are the database dates within a week of the report date?
• Fix within – typically should be under 50-60 ft
• Observed Distance from PF to AP – if this is over 200 ft (fixed or floating) and not reported as off-station, check comments for reasoning. This is an arbitrary but an easy-to-remember “flag”.
• Not on Assigned Position – is there anything to indicate this might be the wrong aid? Fix within should be reasonably tight – within 50 ft
• Photos should match the aid description and any comments by the AV.
• Camera distance to PF should typically be no more than 30-40 ft at most – ideally under 15 ft for the best detail.

Summary

For reviewers, AVA provides additional confidence in data and report integrity with most sources of manual errors eliminated. Reports are started from the map as the Aid Verifier approaches the aid, the data on the aid comes directly from the Light List or USAIMS, and the position fix is taken directly from the device and cannot be changed. Photos are tagged with data showing where they were taken in relation to the aid.

The information presented here is subject to change over time as we learn lessons from using AV Assistant on a broader scale.

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