10 minute vs 10 mile markers

[Guest airsick]

I am curious as to what people prefer when planning nav's. I use 10 minute markers on my charts for a number of reasons.

 

I figure out what my groundspeed should be before I take off using the weather. Then I know that in 10 minutes I should be nearing a mountain, town, lake, whatever. Even when the weather forecast isn't that accurate I have found it to be quite easy to adjust in flight by a minute or two. I also like the fact that 10 minutes is when I am doing my CLEAROF checks so it aligns nicely with this too.

 

But how do I know when I have gone 10 miles? By my watch I guess. I work out groundspeed and then look for the landmark at 5 mins, 6 mins or whatever the interval works out to be. Advantage here is that 10 miles is 10 miles, no need to change anything in flight. But, 10 miles won't line up with the CLEAROF checks.

 

You could find many pro's and con's with each but I am curious. What do you use and why?

 

 

[Guest Flyer40]

I like 10 minutes because 10 mins is, well, 10 mins. It's a nice round figure. Where as 10 nm could be anything from 3 mins to 10 mins depending on what you fly.

 

To help myself I have pencils marked with VTC flying distance equal to 10 mins, one for the Warrior, one for the 182 etc. They make locating a landmark for the next clearoff easy.

 

 

[hihosland]

for me its 10 mile intervals because the GPS will count off the miles for you,

 

even easier if you fly at 60kts

 

Davidh

 

 

[Flyer]

I put 10 mile markers on the map. Having calculated groundspeed its easy to see how far you've come and how far to go. You can see quickly and clearly how many miles to significant land features and waypoints. Also helps for a fix if you get lost (miles of lostness).

 

Must learn how to use the GPS in the plane one day and stop being a ludite...

 

p.s. I still do clearof checks every 15 minutes....

 

Regards

 

Phil

 

 

[Matt]

I'm a 10 mile marker man...probably because that's what I was taught during my Nav training. Also works well with our CT4 which does just over 2 miles a minute (TAS of 125 knots) but close enough for easy calculations using 10 miles. Also, 10 miles is 10 miles, regardless of what you're flying

 

Cheers,

 

Matt.

 

 

[Guest airsick]

Also, 10 miles is 10 miles, regardless of what you're flying

Sounds dumb but this is one of the reasons I like the 10 minute markers. 10 minutes really is 10 minutes regardless of what you are flying. I have flown stuff that ranges from 80kts cruise through to 130kts.

 

Remembering how long it takes to fly 10 miles is harder in the air than simply calculating it on the ground and marking on the charts. No need to think about it in the air then, just remember to think about the 10 minutes no matter what you're flying.

 

 

[Matt]

Horses for courses and no right or wrong with this one, it's all about personal preference and what works for you. As with Airsick I've flown in aircraft ranging from 50KIAS to 175KIAS, for whatever reason 10 miles works for me but I can see the benefits in the 10 minute markers...either way you've gotta convert distance to time or time to distance.

 

 

[Guest airsick]

Sorry Matt, I didn't mean to imply that you were wrong on this so I hope you didn't take it that way. As I said earlier I am interested to see what others do and discuss (not argue!) the pro's and con's of each.

 

 

[Matt]

No worries, not taken the wrong way at all and apologies if I implied anything other. As the Queenslanders would say - "it's all good mate"!

 

PS - it's an interesting topic, I've not known of anyone using the 10 minute marker before, you've opened my eyes.

 

Cheers,

 

Matt.

 

 

[Guest airsick]

Try it and you will find out how wrong you are.

 

 

[Yenn]

10 miles is always 10 miles, whereas 10 minutes does not equate to any distance due to wind direction and speed. I cannot afford to mark up my maps for the different speeds of different aircraft, so I use distance.

 

I use 6 minutes as it is 1/10 of an hour if I want to plot a detour in flight as 6 mins gives 1/10 of speed as distance travelled. This makes it easy to plot a detour in the near future, but of course most detours are worked out immediately and I use a rough guestimate of angle to detour, change heading and then refine my figures. Seems to work OK for me.

 

 

[Mazda]

I was taught to use 6 minute markers like Yenn. At my 100 knot cruise speed, that also works out to be 10 miles. The best of both worlds? :thumb_up:

 

 

[vk3auu]

"At my 100 knot cruise speed, that also works out to be 10 miles."

 

Only if there is no wind. We don't all have the luxury of being able to fly at that speed.

 

David

 

 

[Mazda]

If only it were the luxury of 1000 knots! "Reheat, reheat, go!"

 

 

[Guest rolfeja]

Hi guys im new here so big ellow to everyone:) Just thought id put my 2 cents in. I use 6 min markers also. I find them really easy to work out your ground speed. if are planing on 100 knots and find that in 6 mins you only get 8 miles instead of 10 you know straight away that your ground speed is 80 knots. It seems hard to work it out accuratley forom just 6 mins though so i normally wait to see how i am travelling in 12 mins and take the average. seems to be more accurate. either way its great fun :)

 

 

[vk3auu]

Although I have the map sitting on my lap, I use the GPS to tell me both how far, what direction and how long to the next to the next waypoint, which is generally a landing strip of some sort. It also tells me my ground speed and automatically adjusts my heading to fly the correct track.

 

You don't find airline pilots sitting there with a Wizz Wheel working out where they have to go, they use technology, which is much more accurate.

 

If the GPS goes tata's, I will resort to the map, but that doesn't happen very often.

 

Why are so many people reluctant to admit that they navigate with the aid of a GPS?

 

David

 

 

[BigPete]

Well David if you're out (of the closet, so to speak) then so am I. :thumb_up:

 

I love my GPS :heart: - I use it all the time. :big_grin: I also take my maps etc on a trip and they stay in the map pocket until I need 'em.

 

So far I haven't had to use them. i_dunno

 

I'm sure that not long ago when they first started fitting compass to aircraft - a fair amout of people would have said "what do you want that for - what's wrong with following roads/train tracks, etc." "You can't rely on them, what happens when they stop workin...." (Sound familiar?)

 

(FLAME SUIT ON)

 

regards

 

 

[Ben Longden]

Mmmmm... seems the '10 minute' men are GPS dependant, while the navigators use 10 mile marks on their maps. *ducks to avoid a smack in the chops* Each to their own though.

 

Me, I was taught to use distances on the map as a basic reference.

 

Its a lot easier to plot your position on the chart, using 10 mile marks.

 

I guess is has something to do with the old Speed = Distance/Time thingy.

 

The big variable with navigation is ground speed.. and by using distances as a reference, you have a constant nav factor.

 

Another factor to consider is the reliability of the GPS unit; can you see the screen when the sun is super bright.. is the power reliable... battery life.. things like that.

 

I was taught the PPl nav at Shepparton, and the idea was that technology is wonderful, but you MUST be able to navigate at all times, especially when technology fails.

 

2.2c worth..

 

Ben

 

 

[Yenn]

If you havn't had a GPS failure yet, you are still waiting for it, because they are not infallible. I much prefer to keep my position visible on the map and would be hard put to find myself after the GPS failed and I had realised it.

 

I have had a total GPS failure and if I hadn't known where I was I could have been in strife.

 

 

[Matt]

As mentioned above I use 10 mile markers but I also use GPS (2 actually) to aid in navigation. I'd classify my GPS usage as my "primary means of navigation", my maps, stopwatch and flight log are always on my lap though and I cross reference my progress (GPS/watch/map/log) at each waypoint and/or every 20 minutes.

 

While I use GPS as the primary means, I don't "depend" on it - I regularly fly nav exercises without them to ensure my fundamental skills are maintained. I make use of the convenience as my primary aid with maps/logs as my secondary aid. It is simply another tool in the toolbox.

 

There will always be two views (usually conflicting) about technology aids in anything in life. How many people have ABS, ESP and other technology aids in their cars? One group of drivers will claim these will reduce driver skill and reduce car control while others will claim they improve safety by minimising the skill requirements of the driver.

 

I think the key is your risk / decision making process - would you fly somewhere using only a GPS that you wouldn't have flown using "classic" navigation tools of map/compass/stopwatch? If the answer is yes then you may need to consider your decision making / appetite for risk.

 

I am yet to experience a total GPS failure, I've had one of our two fail (one of the reasons for having two), I've also had a battery die in my stopwatch (a couple of times in fact) and fall back to my wrist watch. The key is options / fall back positions - the more you have (within reason) the better your chances.

 

Cheers,

 

Matt.

 

 

[Guest airsick]

It is an interesting point about equipment failures. One of the tools they teach you to use in GA is radio nav aids. Although these are 'meant' to be reliable and used as a means of navigation I have had one fail on me before.

 

Flying along with the ADF needle sitting pretty and then it started drifting. Initially I thought the ADF had failed but later in the trip I tried it again and found it to be working. When I returned the aircraft to the school I hired it from I reported it and they checked it out but found no faults. A few days later I began to wonder if the NDB itself had failed and sure enough there was a NOTAM stating it had.

 

The point is? Don't rely on any single piece of equipment. It is all susceptible to failure. Use a few means. Watch the GPS, read the map, use radio nav aids, but not in isolation.

 

 

[peter]

I think the GPS is sensational.

 

Yesterday flew from Goolwa up the western side of the Adelaide Hills, dodging showers, heading NNE, then course change to NW across the hills, dodging more showers, skirting Airspace, then more N up to PT Pirrie, form there it was due N before turning due W across the gulf then SSW to Cowel before turning W to Cleve -- all in the presence of a SW wind varying from 10 to 25 knots. Moving map GPS, spitting out groundspeed continuously with all the changes in heading -- PRICELESS!!!!

 

I carry 2, use them all the time, have the map out on the passenger seat and cross check -- I have several pre marked tracks marked in 20 mile intervals which I leave drawn on the chart as I use the routes regularly -- I know all the ground marks from previous trips so I don't mark anything on the charts -- I just fly the plane.

 

GPS primary nav tool, you bet. Runs on planes 12 volt system but with battery backup - unbeatable.

 

 

[BigPete]

Good onya Pete. Way to go. :thumb_up:

 

(pssst Hey David looks like you and I started somethin')

 

Perhaps a new survey regarding primary means of Navigation

 

NB. I plan my trips very carefully and include man made waypoints, (silos, wailway twacks, (stop it!), powerlines (the big ones), and natural ones (lakes, rivers (mostly dry (sigh)), etc. :big_grin:

 

I even avoid tiger country and plot the avoidance on my GPS. AND I have everything plotted on the maps and take the appropiate equipment so I've got it if I need it. :)

 

THEN - I sit back and enjoy the flight.

 

regards

 

 

[Guest Flyer40]

Ben, I learned to use 10 minutes before I graduated to the luxury of GPS. Obviously your instructor/school is a big influence, but I also think it depends on your speed. If you're lucky enough to have a GS of around 150 then a 4 minute marker is just not practical.

 

Peter(s) you guys show how easy it is navigate safety and effectively with GPS. As long as you use a map to record your position every few minutes, so what if the equipment fails? You're never more than a few minutes from your last known position.

 

Surely you'd have to be practicing very poor airmanship and probably flying without a map for a GPS failure to be a problem.

 

 

[peter]

Why do you need to know your position every few minutes? We fly visually so it is pretty hard to get lost - you don't need to know exactly where you are to be able to find your way to a destination -- otherwise most of us who sailed long distances pre GPS would not be here today!!!! You just need overall situational awareness.

 

For example if you are west of the hills in Adelaide and get "lost" you only have to turn either east or west and you will soon run into either the hills or the river and immediately you are "found" again. The only advantage to knowing your position with "precision" is if you are either close to controlled space or you are in an emergency, and I'm pretty confident that the day I use the word Mayday it will be closely followed by my GPS coordinates not an estimate from my last estimated position.