I left World Wide Aerial Surveys and commenced with Adastra in April 1957 and a month later I was officially operating as navigator. The first aircraft I was slotted in as navigator was Adastra’s Avro Anson VH-AGA based at the time in Essendon, Victoria. Later, Adastra acquired another Anson, VH-BLF, and my first stint as navigator with her was when she commenced operations in Sydney, NSW in April 1958. The navigational facilities were exactly the same but the prime difference with the aircraft was that BLF had electric starter motors and electric gear retract mechanism, the latter being easier on the navigator. (See Wal Bowles’ story on Operating the Avro Anson).

A typical day in operation was to get out to the airport if the weather was satisfactory and select the camera to install for the prime project on the list. The pilot would go to flight planning and give the pertinent details of our ETD, transit to the survey area, the height (above terrain) and size of the area, number of runs, estimated time of operation there and ETA back at Essendon.

Whilst awaiting the pilot's return, the engineer would be attending to his “daily”, the camera op would either mount or check his specific camera and peripherals, and the navigator would re-check his survey map details which he generally would have done earlier that day or the previous night.

When the pilot returned and all was checked and ready for start-up, the Anson's Cheetah engines required a crank wound inertia start which at times could be time and energy taxing and the camera op was sometimes required to assist in starting. Later this problem was overcome by Bill Mitchell, an engineer of much resourcefulness! (See Wal Bowles’ story Starting the Anson for Bill’s starting method). Immediately after take-off, the navigator (in the right hand seat) retracted the landing gear with approximately 145 turns; OK if bright and alert, not as nice if feeling a little seedy. He also pumped the flaps to specified positions on the pilot's command when required.

When close to the survey area, the navigator would indicate to the pilot the proposed area to start the project and after folding his collapsible seat to starboard, would crawl into position in the nose where he lay prostrate on his stomach. To facilitate some degree of comfort, there was a foam mattress approximately five inches thick and covered with a type of brown “duck” material.

Anson VH-BLF at Essendon in June 1960. (Photo: Kevin Pavlich)

The nose of the Anson incorporated several plastic “viewing” panels crafted by the “Sheeties”. These were modest but appropriate for what was required. These windows comprised a circular panel directly ahead, a small panel on either side and another below the circular panel, all of similar size. There was also a flat panel under the nose ahead of the drift sight (all of these for forward viewing), a panel either side of the nose, level with the navigators head (for viewing the next flight line) and a couple of small circular windows slightly behind and above these to provide light for map reading.

The main instrument utilised for survey correction was the Aldis (Drift) Sight compiled for operation with the Williamson Eagle IX camera. In other words, if using a 6 inch lens with the Eagle IX, the appropriate 6 inch sight was installed. The sight was situated in front and close to the navigator with the top and middle section available for manual correction with the base (and prism mirror) exposed to the elements. The movable prism mirror was used to look forward in various degrees from directly ahead to behind the aircraft. Viewed when looking through the sight was a marked square relative to the Eagle IX format with lines marked for time interval and a feature that moved with ground speed from one specified point to another. This was checked with a stop watch for a 60% forward overlap plus marks at either side to adjust 25% sidelap. There were also two (close) parallel lines running top to bottom in the center where again a ground feature was traced to keep between the lines to find and adjust port or starboard drift. The result could be read from a scale graduated in degrees circling the outside body at the top of the sight near the leveling adjustment.

The navigator passed on drift correction for the camera and time interval correction (for forward overlap) for the intervalometer on both the Williamson Eagle IX and OSC (Ordnance Survey Camera) cameras. For all the Wild RC series cameras, the camera op had built in facilities for these two applications and the navigator (unless queried by the camera op) was relieved of this duty.

The Anson was used frequently for survey below 10,000 feet but carried oxygen because quite a number of projects were flown up to 16,000 feet (it took a while to get there!). The lowest photo navigation survey (that I did) was 900 feet.

All the work that I as navigator was involved with in the Anson was on a “center-line” basis, either using maps generally and at odd times (mainly geophysical) photo mosaics prepared prior to the survey. The map could have been compiled at the HO, but often to take advantage of a new contract, it was compiled by the navigator in the field after ascertaining the contract border area and scale details so that after acquiring the specific map that included the contract area, he would configure the height to be flown for area coverage and mark in the center lines to be flown that would incorporate the 25% sidelap.

Once in the area, the navigator would guide the pilot to a point approximately 5-6 nautical miles from the start of the first line. All flight lines (unless a tie line or a special contract) always ran in an E-W or W-E direction. After initially giving the pilot ever decreasing corrections to straddle the line, the navigator would ascertain the correct drift and give the pilot a definite heading, (say 266º after applying 2º of starboard drift). After checking for forward overlap, he would pass the drift and time interval on to the camera operator. It was always required for any photo survey that at least two photos (or principal points contained therein) should be outside the border of the area, and if the navigator were happy with all at this stage he would give the “CAMERA ON” command. If he were not sure that he had all the details correct in time to start, he would advise the pilot and camera op and ask the pilot to go around so that he could go through the preliminary actions again to get the camera on and be operational. Once established on line, he would continually monitor drift and time interval and pass any corrections to the pilot or camera op. Towards the end of the line he would look at the next line so that he could memorise features of the terrain to make it easier on the run up to it. After he was satisfied that he had completed the line, he would give the command “CAMERA OFF”. He would still go on a little further before telling the pilot to come around to port (or starboard) to go through the prelims of starting the next line. If the drift was fairly consistent, the camera op would have a reciprocal drift to apply to the camera and the pilot would have an idea of a reciprocal heading before commencing the next line.

As the day continued, provided there were no problems with weather, survey or aircraft equipment, the task became easier because of application continuity. After a few lines, the pilot could get very close to the heading of the new line after finishing the previous line. Fuel endurance and shadow interference, (it was unusual to survey prior to 9am or after 4pm), were also factors to be taken into consideration when planning.

For the navigator it was very difficult after a couple of hours of lying on the stomach with your elbows propped, moving maps and adjusting the drift sight, craning your neck over the sight and gazing through the different panels. Eventually it became quite uncomfortable in what should have been a resting position. Another factor that affected us all was the cold. In the Anson, there were heaters, but after a time at the higher altitudes, they lost their efficiency with the consequent crew discomfort and loss of proficiency at their task. All the Geophysical survey was flown in Anson VH-BLF. Contract AH138 was flown at 350 feet and contracts AH139 and AH140 were flown at 500 feet. These were all mineral contracts flown early in 1960. Geophysical survey navigation was different in that most of the lines were marked on photo mosaics and more latitude was given on straddling the line. I navigated from the cockpit and approached the line as in photo survey and still gave the “camera on” command to the technician at the commencement of the line so he could switch on the “trailing” camera that identified features to confirm that we were indeed on line. Similarly, I gave a “camera off” command on completion of the line.

Pilots who flew either VH-AGA or VH-BLF during my time with Adastra.

Extra Curricular Activities Navigating in the Avro Anson.

Kevin Pavlich
19th October 2004