10 minute vs 10 mile markers

[Guest check-in]

Charts being so expensive, I don't mess 'em up with 10 anythings. Just draw a pencil line of where I wanna go and make sure it's not more than xxx nm from takeoff to landing (safe forecast range of whatever it is I am flying). Make sure that there is a 'bolt-hole' at least 20% less than the safe forecast distance, in case of big bad headwinds which really knock these slow bugsmashers around. The bolt-hole does not have to be on track, but the distance to it from an abeam position should be 20% less than the max safe range for the day.

 

Now, I fly along the line, adjusting for the drift as I go (no complex 1 in 60, just a continuous correction by map-reading - all right, I cheat a bit with the GPS to get the drift nailed but I do take note of it and what the wet compass reads with it corrected). Measure distances and times between identifiable points along track or abeam. I use transits a lot (secret sailor stuff, but it's buried somewhere in aviation text, too). No point in a 10 minute or 10nm marker if there is nothing to look at on the ground to match with it (comes from too many hours over the ocean where neither marker system works very well). At every good fix, I get a groundspeed (more out of curiousity because it does not matter- if you use proportions). With a bit of mental arithmetic even this does not require a whizz-wheel to be close enough e.g. 30 nm in 18 minutes = less than 2 miles a minute so it can't be 120 knots, but better than 1 1/2 miles a minute so it's not as bad as 90, so must be about 100 knots. But like I said, ground speed is only of academic interest because it is TIME that matters in navigation. Fuel runs out on time.

 

So, using the Sonex which has a safe 300 nm still-air range (with reserves) and setting out to do 300 nm on a supposedly light and variable winds forecast. Say my 1st fix is 30 nm along track, already two minutes late; next fix is 50 miles ahead = near enough to another four minutes (err on the safe side, don't be anal about the decimals), so 80 nm into the flight I expect to be six minutes behind. At the 240 nm point, likely to be 18 minutes late, so obviously won't make 300nm if that proves to be the case. Time to consider the bolt-hole unless things improve.

 

 

[Guest Maj Millard]

Sounds fine to me check-in, pretty close to what I have done for 20 plus years and I haven't got lost or run out of fuel yet !.....Once again the KISS theory...keep it simple stupid!..................................................................

 

 

[FlyingVizsla]

I use 10 NM markers as we have 4 planes scooting along from 65 to 95kts with fuel capacity of 15 to 150 litres. I was taught to rule the track and then drift lines with degrees, cumlulative miles and then to write in the projected time to each, then the adjusted time - in chinagraph. It didn't leave much map visible, so I cut it back to track, 10NM markers and noted the time, given weather, to the first 3 (after noting time of departure over the field) and then recalculated to significant terrain and ETA.

 

I loved the cellosheen coating on WAC charts, but Airservices has discontinued this. It was easy to wipe off the chinagraph pencil and use it again. I still have some WACs that Laurie Curley (deceased LAME) had drawn, in thick texta, his favourite routes making it impossible to use them for anything else. I've gone back to covering with clear contact. The draw back to Chinagraph pencils is that they melt if left in high temperatures so I use biro caps on them. They come in many colours and I found it much easier to do planning in brown, recalcs in another colour, and scrawl other info (call signs, levels etc) on another part of the map that can easily be rubbed out when not required. I also had a printed laminated A4 sheet that I used for ATIS info. A word of caution on colours - if you do night flying make sure you can still read the colours under red light - some of the detail on WACs fade out of existance under the red cockpit and torch light.

 

For those who don't know - a chinagraph pencil has hardened wax (rather than lead) and is sometimes known as a grease pen. It is a bit like a crayon in a wood pencil but softer. It doesn't need much pressure so it does not make indentations in the map. It wipes off with a soft cloth, tissue, metho or any number of grease cutting household cleaners. They are useful for marking glass.

 

Sue

 

 

[GraemeK]

Chinagraphs are great! On my desk, I have a PCA chart under a transparent desk pad.

 

So when I get the area forecast, for instance, I can mark the fronts and troughs with the Chinagraph to get a feel for developing weather - or rough in tracks before going to WAC.

 

Then wipe it off!

 

On navs, I reckon the system in book 3 of Fly Better is nice and simple (simpler the better) but does everything you need.

 

 

[Guest skyspud]

10 mile marker from destination backwards. Put in your planned ETA then req'd time intervals back from there. This is how it was taught to me.

 

Never heard of 10 minute intervals but can see pro's for it. CLEARO checks as mentioned, change tanks etc.

 

Use what ever works for you.

 

skyspud

 

Go fast and take chances

 

 

[Yenn]

I like the 10 mile markers as I can estimate tha actual distance covered. One snag with using contact on WAC charts is that the colours can run in the glue. It has happened to me.

 

 

[kgwilson]

Plot your course, determine waypoints (non GPS) halfway etc (distance in NM) & ETAs to these (time). Time = fuel burn, Distance = Am I there yet. look out the window constantly & cross refence with the map (not so easy over desert or water) but mostly you will know. We have to call a minimum of 10NM out in CTAF.

 

The point here is both distance & time knowledge are essential for any pilot on an XC trip.

 

Kevin

 

 

[rgmwa]

I use 10 min markers because that's how I was taught. Never thought of using 10nm markers, but I guess as long as you can figure out where you are, either system is fine.

 

rgmwa

 

 

[Guest davidh10]

10 mile, but marked backwards from the destination... Are we there yet?...no but we have xx? to go based on ground speed, which can be read from the GPS. Obviously, the first mark gives the location for the 10 mile in-bound call.