Map Reading
Watch out if you get a custom 25k. If you live on a boundary between maps you can get one half of the map with 5m contour intervals and the other half with 10m intervals. That'll really drive any navs balmy!
Avoid imitations
Join Date: Nov 2000
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I think in those featureless terrain scenarios the SOP is to deliberately track left or right if the target, so that when you hit the line feature you can turn appropriately and be sure to find it. If you try and aim for the target, chances are you’ll miss and hit the line feature but not be sure which side!
I think it was Sir Francis Chichester who explained how this was a preferred technique of his when sailing across oceans.
I have not used a compass in anger while hiking in many years. Superseded by a handheld gps in 2003 and latterly a mobile phone with a decent navigation app, the gps being relegated to back up device.
The best navigator I ever saw had never been taught to navigate, at least in any conventional way. One of our Bougainvillean assistants offered to navigate us about 10km through thick jungle, pretty flat so no terrain features to work from, to a point on the river. No map or compass with us. He led us to a point about 10 metres from the target.
Three quarters of a life time ago I found myself crewing a RAAF Dakota on a most circuitous route between Butterworth Malaysia and East Sale Victoria Oz. We departed Davao, Mindanao for Koror, Palau at around 0200 hrs local, a 7 hour overwater flight. Our navigation aids were, ADF, drift sight and Astro.
After takeoff, but before being established on an outbound radial, the runway lights, NDB, and VHF comms were turned off. There was little incentive to head anywhere but out to sea as, Mt Apo, a 10,000 ft hill is less than thirty miles from Davao.
After 7 hours in cloud, with no nav other than DR, our navigator called TOD, and bravely predicted that Koror would be at 12 o’clock, about 30 miles.
We broke cloud and of course it wasn’t. We had no VHF or HF comms with anybody.
The next hour or so was spent applying tropical navigation 101, as we poked around exploring under the largest of the slowly developing early morning Cu until we found Palau.
Didn’t do any map reading for the entire flight.
After takeoff, but before being established on an outbound radial, the runway lights, NDB, and VHF comms were turned off. There was little incentive to head anywhere but out to sea as, Mt Apo, a 10,000 ft hill is less than thirty miles from Davao.
After 7 hours in cloud, with no nav other than DR, our navigator called TOD, and bravely predicted that Koror would be at 12 o’clock, about 30 miles.
We broke cloud and of course it wasn’t. We had no VHF or HF comms with anybody.
The next hour or so was spent applying tropical navigation 101, as we poked around exploring under the largest of the slowly developing early morning Cu until we found Palau.
Didn’t do any map reading for the entire flight.
When you life is at stake, one's faculties are sharpened. Back in the 1980s a very old coastal merchant navy skipper of my acquaintance was known to navigate around the North Sea largely by the shape, direction and frequency of the swell. He once woke from sleep in his cabin, sure that the ship was in the wrong place. He was right, and got to the wheelhouse in time to avoid grounding on a sandbar. The officer of the watch had missed seeing the buoy at which he should have altered course.
When you life is at stake, one's faculties are sharpened. Back in the 1980s a very old coastal merchant navy skipper of my acquaintance was known to navigate around the North Sea largely by the shape, direction and frequency of the swell. He once woke from sleep in his cabin, sure that the ship was in the wrong place. He was right, and got to the wheelhouse in time to avoid grounding on a sandbar. The officer of the watch had missed seeing the buoy at which he should have altered course.
As to the map orientation debate: We all have our own preference, but for me it depends on the type of navigation. For precise navigation following features (eg orienteering) map in direction of travel wins every time. When general positional awareness is more important than precise location - sailing, flying (at reasonable speeds, a sensible distance from the ground), hillwalking - it's always North up. My mental map for sailing races (which often use standardised courses oriented to the wind) is Wind up.
Poor Situation Awareness.
An extract from ‘Wayfinding’ Michael Bond
"Modern humans interact with the world in much the same way that prehistoric humans did. We may travel further and faster, and we have some fabulously clever instruments to help us get around, but the manner in which we use our brains to stay orientated is not so different,
We scout landmarks, attend to our surroundings, memorise vistas, build 'cognitive maps' and generally keep our spatial wits about us, just as the hunter-gatherers of the Pleistocene did. Some of us are a lot better at this than others, and that is the way it has always been.
At least, this was the case until around the year 2000; since then, a great deal has changed. Many of us now delegate all that cognitive heavy lifting to GPS-enabled navigation tools, which guide us where we want to go without us having to attend to anything. Follow the blue dot on your smartphone app or obey your satnav's spoken instructions and you'll arrive at your destination without having troubled the place cells in your hippocampus or the decision-making circuitry of your prefrontal cortex. You won't have to know how you got there or remember anything about the route you took.
For the first time in the history of human evolution, we have stopped using many of the spatial skills that have sustained us for tens of thousands of years."
GPS turns the world into abstract embedded in a digital device. Web searches, instant answers, we exchange these for absolute certainty, we sacrifice our sense of place - replacing cognitive skill with technology - reassign mental resource.
Todays (mapless) need is to pay attention to the surroundings, build a mental map, note the shape character of items, links, sequence of turns; without these we lack the projection aspect of situation awareness, not being able to thinking ahead, or being ready for surprises. … we move through the world unaware, and not be affected by our lack of knowledge. No immediate raw experience of the real, we miss the opportunity to develop rich knowledge an rich remembering.
The issue is not to stop using the technology, its being aware of the decision and the effects it might have.
"Modern humans interact with the world in much the same way that prehistoric humans did. We may travel further and faster, and we have some fabulously clever instruments to help us get around, but the manner in which we use our brains to stay orientated is not so different,
We scout landmarks, attend to our surroundings, memorise vistas, build 'cognitive maps' and generally keep our spatial wits about us, just as the hunter-gatherers of the Pleistocene did. Some of us are a lot better at this than others, and that is the way it has always been.
At least, this was the case until around the year 2000; since then, a great deal has changed. Many of us now delegate all that cognitive heavy lifting to GPS-enabled navigation tools, which guide us where we want to go without us having to attend to anything. Follow the blue dot on your smartphone app or obey your satnav's spoken instructions and you'll arrive at your destination without having troubled the place cells in your hippocampus or the decision-making circuitry of your prefrontal cortex. You won't have to know how you got there or remember anything about the route you took.
For the first time in the history of human evolution, we have stopped using many of the spatial skills that have sustained us for tens of thousands of years."
GPS turns the world into abstract embedded in a digital device. Web searches, instant answers, we exchange these for absolute certainty, we sacrifice our sense of place - replacing cognitive skill with technology - reassign mental resource.
Todays (mapless) need is to pay attention to the surroundings, build a mental map, note the shape character of items, links, sequence of turns; without these we lack the projection aspect of situation awareness, not being able to thinking ahead, or being ready for surprises. … we move through the world unaware, and not be affected by our lack of knowledge. No immediate raw experience of the real, we miss the opportunity to develop rich knowledge an rich remembering.
The issue is not to stop using the technology, its being aware of the decision and the effects it might have.
I can't get my head around that at all; having spent far too much of my time on boats, the only waves I see are related to the wind. Nevertheless, the same techniques have been used to navigate parts of the Pacific for time immemorial, and the charts were made from sticks.
As to the map orientation debate: We all have our own preference, but for me it depends on the type of navigation. For precise navigation following features (eg orienteering) map in direction of travel wins every time. When general positional awareness is more important than precise location - sailing, flying (at reasonable speeds, a sensible distance from the ground), hillwalking - it's always North up. My mental map for sailing races (which often use standardised courses oriented to the wind) is Wind up.
As to the map orientation debate: We all have our own preference, but for me it depends on the type of navigation. For precise navigation following features (eg orienteering) map in direction of travel wins every time. When general positional awareness is more important than precise location - sailing, flying (at reasonable speeds, a sensible distance from the ground), hillwalking - it's always North up. My mental map for sailing races (which often use standardised courses oriented to the wind) is Wind up.
It may or may not be true, but I was told that when the Australian Army allowed women to go into field roles, they had to change their ways of teaching navigation, as women navigated differently too men. Someone here may know whether or not that's true.
Join Date: Feb 2006
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Originally Posted by [email protected]
I did see a Decca moving map fitted once - horrendous. ISTR crossing the Irish Sea from Aldergrove to Valley was a crap area for Decca coverage.
I also remember the tale of a Puma Nav doing a Decca internal SRA, who offset one lane to the right to compensate for the crosswind
I also remember the tale of a Puma Nav doing a Decca internal SRA, who offset one lane to the right to compensate for the crosswind
https://www.ebay.co.uk/itm/195671330...Bk9SR-qNteH3YQ
Tales of now-defunct nav systems and techniques:
The HS121 Trident (British B727 lookalike for those unfamiliar with this beast) had a moving map display driven by Doppler drift and groundspeed. It never worked.
On some of BEA's post-war fleets aircrews included a Radio Operator. The IR renewal included a VDF let-down (civil version of the RAF QGH). One story has it that on a practice VDF the R/O would look out of the window to determine geographic position, work out the equivalent bearing and pass it to the pilots as if it had been transmitted by ATC.
One of the navcom manufacturers (Narco?) in the early 1970s produced a 'course line computer' system based on VOR/DME. You could generate a 'ghost' VOR/DME by displacing the actual beacon along a specified bearing and distance. As an example you could move Daventry VOR/DME 22 nm and 207 degrees (magnetic, variation 7W) to position it over Oxford Kidlington.
Also in the 70s someone contrived a map system to work out 2-position line fixes using bearings from two VORs read along axes at right angles - a good idea except that the maps were highly distorted.
Basic air or surface nav:
Daytime directional orientation without GPS or compass: sun position and a reasonable idea of local time;
Or: if sun obscured, wind direction (assuming it hasn't changed since departure)
Nighttime ditto: Polaris
Map-reading: many GA pilots who use GPS also print out the intended route map (using SkyDemon or similar). So the magenta line (dread phrase) is on a piece of paper for when the electronics go AWOL.
The HS121 Trident (British B727 lookalike for those unfamiliar with this beast) had a moving map display driven by Doppler drift and groundspeed. It never worked.
On some of BEA's post-war fleets aircrews included a Radio Operator. The IR renewal included a VDF let-down (civil version of the RAF QGH). One story has it that on a practice VDF the R/O would look out of the window to determine geographic position, work out the equivalent bearing and pass it to the pilots as if it had been transmitted by ATC.
One of the navcom manufacturers (Narco?) in the early 1970s produced a 'course line computer' system based on VOR/DME. You could generate a 'ghost' VOR/DME by displacing the actual beacon along a specified bearing and distance. As an example you could move Daventry VOR/DME 22 nm and 207 degrees (magnetic, variation 7W) to position it over Oxford Kidlington.
Also in the 70s someone contrived a map system to work out 2-position line fixes using bearings from two VORs read along axes at right angles - a good idea except that the maps were highly distorted.
Basic air or surface nav:
Daytime directional orientation without GPS or compass: sun position and a reasonable idea of local time;
Or: if sun obscured, wind direction (assuming it hasn't changed since departure)
Nighttime ditto: Polaris
Map-reading: many GA pilots who use GPS also print out the intended route map (using SkyDemon or similar). So the magenta line (dread phrase) is on a piece of paper for when the electronics go AWOL.