Aviation charts were first developed in the 1930’s to allow navigation by reference to visual landmarks. However, a fully opened chart is rather unwieldy in the cockpit of a small aircraft. This post attempts to retrieve a method suggested by a Duncan McKillop (probably from the 1990’s) as well as an improvement to the fold by Steve Hirlehey (January 2006).
Duncan McKillop method
The most common reference is to a Duncan McKillop from the United Kingdom, who probably in the 1990’s, suggested a folding method posted to a mailing list or internet forum with this current incarnation.
The Duncan McKillop method is both simple and effective. In brief:
- a large rectangular aviation chart is folded to have:
- 3 equally-spaced folds parallel to the long edge, and
- 7 equally-spaced folds parallel to the short edge.
- these folds are creased strongly in both orientations
- … and then the folds are made “concertina style” – which, in orgami terms, mean alternating “mountain” and “valley” folds – to allow access to different areas by “turning the pages” of the folded chart without needing to unfold the entire chart
I was unable to find Duncan McKillop’s original post but did find a reference at http://www.wingweigh.co.uk/chartfld.htm with the attribution “Reproduced From an Idea by Duncan MacKillop (sic) via the Flyer list”. This page has existed since September 2001, which is why I think the original post might be from the 1990’s. (The filename is curious – 8 characters and a 3 character extension, consistent with last century naming restrictions.)
Here are Duncan McKillop’s presumed original instructions, as passed down on the internet, using the 2001 reference:
- Practice on a sheet of A4 first (writing on one side, blank on the other), this will help you avoid making a mistake with the real thing.
- When folding break the back of all the folds, i.e. make the fold one way and then turn the sheet over and make it the other way, this helps the finished chart to lie flatter.
- Finish each fold by running along it with a hard edge, this makes a fold, not a bend.
- Give yourself plenty of room on a big table.
- Get a friend to help you keep the folds from going wrong
- Be prepared to modify the instructions for charts that are taller than they are wide, Scottish chart for example.
- If you never want to look at the key panel across the bottom of the chart, simply fold it back out of the way and treat the remaining area as per the following instructions.
If you get it right you will end up with three horizontal and seven vertical folds.
- Fold 1. With the chart printed side down, fold the two longest edges of the chart together so that you get a nice fold running east west along the middle.
- Fold 2 & 3. Open out the chart and fold the lower edge up to the centre fold, repeat for the top edge.
You should now have three horizontal folds running east west across the chart. (If you haven’t, give up and go down the pub!)
- Fold 4, 5 & 6. Open out the chart and repeat the previous process, only this time make the folds north south.
You should now have three horizontal and three vertical folds dividing the chart up into sixteen little squares. (Fun isn’t it) All of the remaining folds will be north south.
- Fold 7. Open out the chart printed side down and take the left-hand edge and position it on the first fold in from the right-hand side. Take a soft pencil and write “not this one dummy” along the resulting fold (You’ll see why next).
- Fold 8. Open out the chart again and repeat step seven again only this time from the other end. By writing along the previous fold it will hopefully stop you making fold 8 in the wrong place! Remember to fold the edge to the FIRST fold at the other end.
You should now have five vertical and three horizontal folds, if not, the pub option will apply.
- Fold 9 & 10. Open out the chart and fold the left-hand edge in to the first fold on the left-hand side. Repeat for the right-hand edge to the first fold on the right-hand side.
You should now have completed all seven vertical and three horizontal folds and all the vertical holds will be the same distance apart. No? Pub!
- Final assembly. Open the chart out flat on the table printed side down and fold the top and bottom segments into the middle. Turn the chart over with the open edges away from you. Starting with the top fold, make the first fold away from you. Next fold towards you, next away and so on until you have a series of concertina folds.
- Open the folds out between the second and third peaks of the concertina, turn it through 90 degrees and fold the top away from you.
The job is now finished (yipeee). To use, flip the chart open so that there is an equal number of concertinas each side and page left and right through the concertinas to see the centre portion of the chart. To see the upper and lower portions of the chart, flip it over towards you and page left and right through the concertinas.
If all this is far too confusing for you, buy a pre-folded map!!
To be honest, following the text instructions was a little difficult, so I searched a bit more and found what sounded like a nice improvement.
Steve Hirlehey’s improvement
While searching for instructions (and videos), I came across a 2020 YouTube video “Folding an Aviation Chart with Troy Williams | Bristol & Wessex Aeroplane Club” with a modified Duncan McKillop method.
The improvement was to NOT make the folds evenly-spaced, but to leave small amounts of wiggle room to allow the folded map to lie more flat when folded and back-folded upon itself. In the video, you can see printed instructions that looked really clear, but sadly the link to the PDF referenced in the video (somewhere on https://www.aopa.co.uk/) no longer works, nor did Steve Hirlehey’s own link to the method.
Internet Archive to the rescue again! From a web crawl dating back to February 2006, I was able to retrieve the original PDF file seen in the YouTube video: FoldingahalfmilUKaeronauticalchart.pdf, created by Steve Hirlehey, January 2006.
Folding an aviation chart, Steve Hirlehey
In case the Internet Archive PDF is ever lost, here are the pages (but exported as JPEG). (Or I can also try to host the PDF on DropBox.)
Page 1
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Final result
Following those instructions carefully yielded a beautifully compact chart, shorter than a typical kneeboard and nicely squared off.
Looking at it edge-on, you can see how Steve Hirlehey’s modification to the Duncan McKillop methods allows a bit of space between the folds, which I think helps a lot with keeping the map folded down flat.
During both my first ever single leg cross-country flight (with an instructor) and my first solo cross-country, it was significantly easier to follow along the route of flight without needing to fully unfold the chart.
It’s a great method! (But, I’ll probably still someday get an iPad to do the same task more effectively, with current century technology.)