Student Navigation - Time or "Fractional" Marks?

[fireflybob]

As an instructor, do you prefer your student to have "time" marks (say every 5 minutes) or "fractional" marks (say quarter, half and three quarter marks of distance along track) plotted on the planned track?

Personally, I prefer fractional marks since this makes revision of ETA easier - ie one minute late at quarter way means two minutes late halfway, etc., whereas time marks assume that the grounspeed is correct.

Just wondered which you preferred to use and why?

Also, what do you think is the key to teaching pilot navigation and do you have any handy tips for making the learning process quicker/easier?

[Stan Evil]

Fractional marks are great as long as they're at visually significant check features. A half-way mark in the middle of a field is useless. Moving the marks a bit either side of their mathematically correct position so that they're over/next to a town, motorway junction etc has almost no effect on the maths of navigation but now means that you've got a check feature. Divide the track up into chunks of between 6 and 10 minutes by using halfs, thirds or quarters as appropriate. Use one of the normal track correction methods and have a work cycle based on the time between fixes so that you spend lots of time looking out and flying your heading accurately; leave navigating to the couple of minutes before a check and a minute or so afterwards while you do the sums and make the corrections.

[foxmoth]

I tend to teach both and point out that some legs suit one method of marking and some the other, 6 min marks are best if you are using time markers as this is 10% of your g/s therefore easy to work out. The MAIN thing with nav is not to overnavigate, if I find a student doing this I take the map away from them after a check point and give it them back 2 mins before the next time point.

[Wee Weasley Welshman]

I teach both with the aim being to use a sensible mix of both.

On longer legs - such as will be flown commercially or on a CPL test - a slavish adherence to one or'th other will not be the ideal.

By personal preference I prefer to use a % marker per waypoint and mentally or pre-plen % of leg time. With a little practice this become very accurate. It also works well when applied as a skill to fuel consumption.

WWW

[Say again s l o w l y]

Going to reiterate what everyone else has said, but...
Both methods have their merits, but as a rule I like my students to use the fractional method, simply as it needs less brain power. On long legs though, as said by WWW, especially if it is rather featureless the time method always works well. Though I always like my students to mark a positive fix on their map including a time no matter which method they are using. It helps if it all goes T*ts up later on.

One way of making Nav seem less daunting to most people may seem strange, but getting studes to practise mental arithmetic seems to make a big difference, especially when calculating ETA's. I'm amazed how poor most people's mental calculating power is and that it really can be a stumbling point, as they spend so long worrying about it that everything else goes out the window!

[BEagle]

Definitely use the estimated elapsed time at obvious visual fixes, but choose such fixes so that they are at rough fractions of track distance. That motorway at 40 miles along a 70 mile track is near as makes no difference about halfway along track! But the only other marks worth using are 6 minute marks to give a rough idea of position; however, exact 'fractional marks' are pretty pointless unless they happen to concide with something visually significant.

DON'T plan too many fixes, the emphasis is on planning accurately in the first place, looking out, flying acurately and thinking ahead. A student who spends too much time trying to map read, do hard sums or write on a complicated log is less likely to have flown accurately enough to make proportional correction of timing at pre-planned visual fix points. If the student finds that he/she/it is 30 sec late at rthe fix about 1/3 way along track, a corrction of 1.5 minutes to the leg ETA is only valid IF the correct IAS has been maintained on the first 1/3 of the leg. If he/she/it has been wandering about over map reading and hasn't been keeping an accurate speed, the only correction should be to apply 30 sec to the leg ETA and to make any other ETA corrections at the next pre-planned fix point.

Navigation - it can't be difficult if navigators can do it!!

[Charlie Foxtrot India]

The various methods all work, and I find students understand navigation better if they think of the track as a "time line" rather than just a direction. This helps to prevent them from quickly being convinced they are where they think they might be, (vague) rather than where they actually are. (definate)The time line will tell you, and when you check position go "what time is it (clock) what should I see at this time (map) and am I there(ground)?"
To make the mental arithmetic easier I teach ten minute marks working backwards from the destination - the ten times table is easier than the six times table when it comes to mental arithmetic. Any odd minutes are at the start of the leg while climbing etc. You then have a prompt every ten minutes to do your FREDA checks and prepare for the next ten minutes workload, particularly when inbound to the destination, and a "sub" ETA which will tell you if your groundspeed is different to that calculated on the ground. And hopefully will never be more than ten minutes off track!
If everything is in minutes, ETA, fuel log etc you have one common denominator rather than trying to grapple with minutes, litres and miles.
Students who do their prep diligently have few problems, especially if they "walk through" the exercise before flying it. One of my instructors chalks it out in front of the hangar, and they literally pace through it, it works very well most of the time - until someone comes along and parks a plane on top of your "destination"!!
The most common part of navigation that people seem to find hard, and which lets them down in flight test, is planning the descent and entry to an uncontrolled airfield. Circuit joining errors are the most common reason I have to fail candidates for PPL. These skills need to be developed early on and any problems ironed out by the third navex before they go solo and develop bad habits. Another thing is that although they have used the wind in planning, lack of awareness in wind direction on a forced landing is the second most common error. Draw a big wind arrow on your map!
Also in the "lost" procedure they need to be able to grasp how far they could have gone since the last fix, like a "keyhole" on the map. some have real problems with this and again ten minute marks help.
Sadly there are some who will never have a sense of direction - I had one who was convinced that East was North and that a couple of large features had moved overnight,
but with patience they can get there in the nd!

[Chuck Ellsworth]

What is a FREDA check?

Flying has so many acronym's it is impossible to know exactly what they all mean.

Thanks.
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The hardest thing about flying is knowing when to say no.

[fireflybob]

FREDA stands for:-

Fuel

Radio

Engine

D.I. (Gyro aligned with compass, etc)

Altimeter

Useful for routine enroute checks etc.

The UK Military use FEEL:-

Fuel

Engine

Electrics

Location

Thanks for all the replies everyone!

[Chuck Ellsworth]

Without offense to anyone, it seems that the training industry is becomming more and more geared toward overkill in the methods of teaching flying.( ie acronyms for everything you do except maybe park your car. ). For instance why does it take forever for an instructor and student to plan a simple VFR x/country, then after the poor student gets his/her first job the employer expects him/her to flight plan and leave in a matter of minutes?

Just wondering why it cannot be more simplified?

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The hardest thing about flying is knowing when to say no.

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[DB6]

Cat driver, of course it can be simplified. In fact I would say that a fair proportion of people after passing their skill test throw the map in the back and switch on the GPS, and it doesn't get much simpler than that. The point is to teach, and to demonstrate on test, theoretical navigation put into practice. That way the student hopefully not only learns a bit about How but also understands Why.

[Chuck Ellsworth]

Hi DB6:

Hmmmm... maybe I should re. state my obversations regarding the level of comprehension of the skills of flying among a large number of pilot graduate's I see in aviation lately.

Some of the problems that I notice are they have been well indroctrinated in paperwork and theory but lack acceptable skills in how to actually fly the airplane.

Then again maybe I just expect to much from flight schools.

To put it simply, I would like to see more emphasis put on how to actually fly the airplane.

Anyhow those are my thoughts for whatever they may be worth.

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The hardest thing about flying is knowing when to say no. :D :D

[ 14 October 2001: Message edited by: Cat Driver ]

[DB6]

True, however in the UK anyway the level of practical flying skills achieved is driven by one main thing i.e. money, and most students understandably do the minimum necessary to pass the skill test. Ground studies generally cost little or nothing in comparison to airborne time so the more time spent preparing the flight the less time wasted in the air. The other thing is that a lot of people do not stop learning once they pass their test and get measurably better the more they fly on their own. So yes I agree with you in part but I did the same thing and made my fair share of cock-ups along the way (and still do occasionally it must be said). The one thing you can't buy over the counter is experience.

[Blue Hauler]

Firefly Bob,

I have to go with distance markers as opposed to time markers. My experience is based on remote area navigation over outback Australia. ADF and VOR were sometimes helpful as off-track aids to determine '‘distance from'’ when passing abeam, but I relied exclusively upon time/speed/distance calculations. WAC in this flat country had excellent watercourses marked (probably about one in ten) and although dry were perfectly readable. Watercourses are like fingerprints. When they cross your track, the smallest watercourse will provide distance information and (by reading their unique bends) track information. But I digress.

Ten-mile markers (I was flying C-180’s in those days) provide an easy method of determining both distance and proportion. After some practice one is able to tick the track at ten-mile intervals reasonably accurately without using a scale rule – a handy trick for quick weather diversions. It doesn’t matter if a checkpoint falls between ten-mile markers as it is very easy to estimate the distance down to a mile or so. The markers also serve as a gauge in estimating off-track pinpoints. All my ‘chinagraph’ pencils were notched at ten mile intervals.

Some legs were two or three hundred miles between towns! Several wind changes could occur enroute particularly when passing thunderstorms or through a front. So whilst a WAC with the appropriate markers is essential, an accurate flight log is equally important. Over such distances I found the need to record TAS, HDG, G/S, TMG and determine W/V. Keeping the log was a chore but paid off on a number of occasions, particularly in the winter when overflying solid stratus for a hundred or so miles.

GPS today is a useful tool but should be treated simply as an aid to navigation rather than a definitive solution. Even when flying GPS/NPA approaches one must use other ground based aids to reinforce the decision process and ultimate survival!

Cat Driver & DB6

Surprisingly many Australian instructors have very little experience in remote area navigation (the odd run to Birdsville for the races doesn’t qualify). The experience they pass on is what they too learned from an equally unqualified instructor during their commercial training. It is a pity that instructor pay is so low leading to flight instruction as a stepping stone to that outback job in a Cheiftain. The experienced bush pilots take their knowledge into retirement!

[Chuck Ellsworth]

Blue Hauler & Firefly Bob:

It is interesting reading how others look at flying and navigating as we always can pick up new ideas.

Blue Hauler I also use maps for a lot of the flying we do, especially in areas that have very difficult landmarks for navigation, we use 25 N.M. check marks on our maps when flying in Africa or South America and record lat & long from our GPS receivers, then if something gets all screwed up we at least know where it went wrong. The Sahara desert is probably the very worst for VFR map reading as it is so vast. The only continent I have never flown over is Australia but I will before I finally retire. By the way GPS is the most reliable nav aid ever invented, we run at least two at all times. When I started flying we used the radio range as our nav aid for IFR then for many years we flew the Arctic using celestial navigation so to have evolved to todays navaids is truly a giant leap foward. Especially the glass cocpit I found it facinating when I trained on the fly by wire glass cockpit.

Anyhow I am happy to have the chance to exthange ideas with all you guys.

By the way any of you who live around London I quite often fly out of North Weald, in fact will be going over to Duxford at the end of the month to move a Cat to Lee on Solent.

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The hardest thing about flying is knowing when to say no. :D

[foxmoth]

Blue H - Just as has been said before, you use the method that fits the leg you have to fly, in AUS with only limited features you NEED to use time markers associated with those features that are available, in the UK/Europe with more features then 6 min marks or proportional marks become more relavent.
Cat driver - I would hope that by the time a pilot is going for his first job he is a LOT faster at planning and more aware of WIHIH than an ab -inito student.

[Blue Hauler]

Foxmouth,

You said “…in AUS with only limited features you NEED to use time markers…” If you re-read my post you will note that I made no mention of ‘time’ markers.

I have flown within Europe and over island countries and my preference in all cases is for distance markers in lieu of time markers. Personally I find ‘time’ markers an increase in workload since unknown variables in ground speed throw the efforts of planning into a heap. Such variables include wind changes, altitude changes or the need to reduce or increase speed to obtain a better SGR.

At the flight planning stage, considerable more time is expended if one has to tick track lines to reflect variations in ground speed as opposed to ten or twenty mile markers. The increased workload adds to the preparation time, a comment suggested by ‘Cat Driver’. By training students in the shortcuts of flight plan prep their ultimate employers will also appreciate the minimal time for maximum preparation.

[Genghis the Engineer]

I'm not an instructor, but do fly around a lot of aircraft with uncertain performance.

I always use the distance marker method - usually 6 or 12 nm markers, depending upon the speed of the aircraft - but any interval will do so long as it's constant. For on the hoof planning, it works wonderfully once you've grasped that airspeed is irrelevant. If you know that you're flying (say) each 12nm interval in 8 minutes, you don't worry about the fact that you're flying at 80 kn, you just use your 8 times table. 5 markers to go = 40 minutes. Cuts a lot of mucking about out that detracts from lookout, managing the aeroplane and spotting landmarks. I find the method, even in a microlight at 40 kn is good for 1 minute in an hour when predicting an ETA.

G

[4dogs]

Folks,
http://www.pprune.org/cgibin/ultimatebb.cgi?ubb=get_topic&f=5&t=000165


:rolleyes: :rolleyes:

[foxmoth]

If you mark a map using distance or time, they are still TIME markers and a student at least should be learning to go from watch to map to ground. BH - Not using them as time points may suit you, but it is not really the way to teach ab initio, and even if you have that many variables, IMHO a student should still be learning time, map ,ground, you just make it that he has a wider time band to operate in.
nb. I don't really see how your variables change so much unless it is either poor planning, poor flying or you are actually doing a job where you are changing your plan. I fly many thousands of miles and usually arrive within minutes of my planned arrival time!

[Blue Hauler]

Foxmouth,
A technique used by some instructors in Australia is to mark the map in 'time markers'. Obviously when tracking into wind, the markers will be closer together than when tracking with the wind. And it must also be apparent that such markers are only accurate when the winds are as forecast. A change of wind or cruise technique renders the marks useless.

By marking in ten or twenty mile intervals, each mark will still be valid regardless of the direction travelled. The time to transit the marks will vary and any student with grade school math should be able to interpret ETA's accordingly!

[foxmoth]

BH - do you HAVE to be insulting in the way you change peoples screen name or is this just your juvenile sense of humour - I could do something similar but have so far restrained myself!
From my experience the Aus met does not get its forecasts as wrong as you seem to indicate and so timings for points closer than 50 miles or so should not be out by more than a couple of mins or so unless you are using the wrong days forecast, even then correct application of ETA updates should allow you to make half decent forecasts for time to turning point.
Also, by using the 'distance' markers is STILL as I pointed out in my last post, using time markers anyway, just instead of knowing the time between points and then working out the distance to mark on the map you are marking a distance then working out the time between points, hopefully you STILL teach that you know when to start looking for the marker point by looking at the watch to know when that point is comming up, or do you just leave it to luck?
An additional point is that, as you have said, using time means that the markers can becloser together on some legs than others due to wind, but you are then doing checks at regular time intervals, what you seem to be suggesting could in theory mean you have a nav check every 6 mins on one leg (fine), but every 20 mins on another leg (not so great), admittedly this would be a very strong wind, but you have talked about WORK, and sometimes then you do fly with very strong head/tailwinds!

[ 26 October 2001: Message edited by: foxmoth ]

[ 26 October 2001: Message edited by: foxmoth ]

[ 27 October 2001: Message edited by: foxmoth ]

[Blue Hauler]

Foxmoth,
My sincere apologies – I misread your ‘handle’ and in no way was attempting to display a ‘juvenile sense of humor’.

My response to the original post by FFB was based on experience in remote areas a long time ago. In that post I pointed out that variations in windspeed and direction encountered on long legs rendered the use of time markers useless. Satellite imagery (in the sixties and seventies) was in its infancy, and in a country this size ‘met’ observers are few and far between. And yes, the forecast winds were not always accurate. Nor are they today.

No, I don’t use six minute intervals. In fact locating suitable features in central Australia at fifty mile intervals can be a challenge unless you dog-leg all over the country side. Ten mile markers serve to quickly calculate the distance between such features and determine G/S. They also enable a quick check of ones probable position by estimating the distance flown over time since the last checkpoint. They are excellent for calculating 1:60 solutions (a distance not time calculation). Most of all they are still on the chart next day or next week when you are tasked to fly the same route, perhaps in a faster or slower aircraft!

Finally you seem to have some aversion to the term ‘distance marker’. To quote a 1983 publication by T. THOM on navigation: “To allow in-flight estimation of flight progress…put in 10 NM markers. Some people prefer to use time markings…but these change from day to day depending on the wind, the aeroplane and so on.” They are measures of distance and not time!

In teaching students I draw on tried and tested practical experience, not necessarily the teachings from a text book. After all the luxury of a classroom does not replicate the confined space of a cockpit bouncing in turbulence and pressed by the urgency of bad weather and/or fuel limitations! Ten mile markers keep it simple.