RAF Navigation "Training"??
 

I was astonished recently to discover that RAF University Air Squadron trainee pilots are no longer taught how to use the basic navigation computer. I had someone in recently who had never seen one before, despite having had 2 years training! Hadn't a clue how to use the back of the circular part to do basic speed/distance/time calculations either. It seems that they just gash about using Mental Dead Reckoning and assume a speed of 2 miles per minute....

I know that HMFC doesn't teach much theory these days - but this is the giddy limit. 17 year old PPL students with 15 hours flying can master the computer, surely 'professional' military pilots should be able to as well?

Good enough for government work;)

jsf

As of about 3 years ago they did teach it, and I suspect they still do. Is is possible your friend has not reached the navigation section? That would not be unusual after 2 years if he did not fly very much.

On the other hand when I did my nav training at JEFTS/BFT we all gave up using the Dalton Computer, and used mental ded reckoning instead. As taught by the military it was perfectly accurate enough, it was quicker and of course it was good practice for airborne replanning where using the flight computer is not a reasonable option.

What is wrong with "...[gashing] about using Mental Dead [sic] Reckoning and assume a speed of 2 miles per minute...."? As taught in the military system it allowed me to find the corner of an individual field, or a rusty wind pump among trees.

What you should ask is can your PPL holder cope with that level of MDR? This is far more important to safe, competent flying than use of the flight computer. I know that I can almost always beat my students to an answer that is easily close enough, be they PPL students or ATPL groundschool students with PPLs and perhaps many hours.

At, say 420 KIAS and 250 ft, where the effect of wind is less, I concede that the LL technique is fine. But at 2500 ft and 90 KIAS, a wind needs to be pre-planned and time at waypoints pre-calculated.

Learn the basics first - including how to use the back of the computer. Then move on to other techniques.

I'm not suggesting, by the way, that there's a need to take the Dalton into the air - just use it pre-flight and then correct in flight using normal techniques.

I had one Qualified Service Pilot who thought that still-air planning and in-flight correction by observed error would be OK at medium level in a Cherokee......

Ermmmmm, BEagle, can I ask you what you think mental ded reckoning actually is?

You seem unaware that it involves taking into account wind to correct for drift and to calculate an approximate groundspeed or head/tailwind component, using that for calculating expected time at certain points (as, it seems, does one service pilot you know, but you don't say how long it has been since he flew slow aircraft). As far as this goes it has exactly the same purpose as the use of a Dalton computer/circular slide rule. The only difference is that it is slightly less precise, but since the precision is beyond that either of wind forecasting or flying headings in a light aircraft that is, in my experience, completely immaterial. It seems you don't know or don't trust MDR techniques, so what are you teaching your students?

I was using these techniques to navigate a Squirrel at 100 kts or 60 kts, down to 200 feet, by the way, and still use them when I navigate myself. They work even at 1 nm/minute TAS. They work extremely well.

BTW my comment on not using Daltons in the air related to diversion nav, not correcting a pre-planned route. You need some MDR technique for planning a route while airborne.

I am entirely familiar with MDR, thank you very much - I fail to see the need for your evident hostility.

The service pilot to whom I referred hadn't flown a slow aeroplane for about 2 years - but had no idea how to use a navigation computer nor how to use MDR to obtain a groundspeed. He just used 1.5 mile per minute groundspeed and guesstimated the headings using 'clock' proportions of max drift. Sorry - I don't think that's good enough. There's plenty of time to do a proper pre-flight navigation plan for a simple triangular navex; in-flight errors should then be relatively small if the plan has been flown correctly. During the diversion element of a PPL Skill Test, the applicant indeed uses MDR after first measuring track and distance....but are taught how to do that properly.

This is basic stuff - all PPL students are capable of it, but why isn't the military bothering anymore? I recall many sessions in a classroom at my UAS, RAFC Cranwell and even at Valley using the Dalton - we had the time then to bother, it seems....

Well your second post had nothing to do with MDR, in fact it seems now to have nothing to do with what your student was doing. He evidently did not think "...that still-air planning ... was OK ..." as you said since you now say he used MDR to account for the wind. That is not still-air planning.

I was redsponding to your obvious negative attitude for which you have given no good justification.

If your friend flew UAS a couple of years ago I can assure you he was taught to use a flight computer. I can assure you the military do still use the basic techniques, as I teach some UAS graduates. I am not entirely surprised that your student can no longer use the Dalton computer, even forgotten about it at all, as most pilots don't like the thing and even more have forgotten how to use it soon after they finish their initial training, EFT or PPL, let alone if they have not needed to for a couple of years (I know I had when I was in that position). You seem very hostile to the military training system, due to a single case, without bothering to consider what can be expected of this person.

Whatever you think, I can assure you that the precision of MDR is "...good enough...". Not only do I think so, as a lowly PPL instructor and ATPL General Navigation instructor, but so do the service instructors I have flown with, and the people writing the training manuals for approved IR training courses, specifically saying that CRP-5s need not be used and giving tables instead with about the same precision as MDR. In-flight errors will not be significantly greater using these techniques.

The purposes of navigation is to get the aircraft efficiently to the desired destination. What does the technique matter as long as it is effective? How do you justify saying this is "...not good enough..." without evidence that MDR is inneffective?

RAF Nav Training
 

Come on, Send Clowns. Don't be too hard on poor old BEags.
He's got a point you know.

We talking here about the difference between casual (sloppy?) and thorough basic understanding of the triangle of velocities here.

I've been flying a fair old time as well and I know what I would use if the vis. was really poor.
We can all remember the 97%, 87%, 75% etc. of max drift ( sin of...)

How many times have you been sitting there waiting for the second hand to come round and there it loomed - that difficult waypoint, right on time, - because you'd taken the trouble to plan it properly ?

Think about it.
Rgds, Sleeve.
:ok:

Send Clowns - no, my QSP thought that a 'standard' GS would suffice and that he could just wag the heading by applying an on-the-day wind to track using MDR. His so-called planning consisted of measuring track and distance - and that was it.

I have nothing against proper military instruction having been an A2 QFI/IRE for many years. But I do not accept that dumbed-down, gash, sloppy basic instruction is in any way acceptable. Students must learn the basics. Period.

No matter - I shall be writing to the CFE to recommend that the credit for the navigation section of the PPL Skill Test for QSPs is suspended. The "oh - it's good enough" attitude has no place in civil flying and I'm surprised that you think that it's acceptable for professional military flying. It b£oody well wasn't when I was a QFI, I can assure you - and I won't accept it now!

So-called military trained pilot scored a mere 48% doing the PPL Navigation and Radio Aids exam yesterday. Frankly, I was appalled. Basic - very basic - errors and an astonishing number of gaps in his knowledge. Mostly not his fault, more the fault of the contemporary cheap and nasty approach to training...

BEagle

Before you take the 'yooful' attitude to immediately go tell the Authority, may I suggest you check out your facts. It would be very unfair of you to deprive Army Pilots of their exemption based on an unchecked opinion of yours. At DEFTS Barkston Heath, they ARE taught the DC.

I agree with you that the DC is a useful tool to become familiar with in Flying Training but it is not what I would call essential. However, I do feel it should remain within the knowledge base of any aspiring pilot.

The truth is, that a QSP has a lot more experience by the time he wishes to acquire a PPL and we do know that MDR for an experienced Pilot, does work very well.

I have to say that I find it hardly surprising that your threat has engendered a rather juvenile response from some PPruners on 'MILITARY AIRCREW'; perhaps it came across in a way inintended,but then your original threat, was rather juvenile.

Concerning:

"They get taught Jack !!!!! as far as the computer is concerned. All they get is MDR! I have to deal with it on the UAS and, as you've said they haven’t a clue. MDR is the ONLY way they are taught; I spend all my time at medium level ensuring they don't get too far off track because they don't listen to met briefed winds or apply the MDR wrongly!"

You seem to have set much store on this comment - I thought it was a UAS Instructors role to teach Navigation using, yes perhaps MDR. You can say the same, if the above UAS student was using a DC.

Point taken - shall not be writing just yet.

Glad to hear that the more senior services are still able to give their pilots a sound level of basic instruction.

That's a good comment on this student, BEagle, and it sounds like he needs rebriefing (although the heading should be OK), but is there any evidence to extend this to the whole system? Sounds like he is just not using the techniques he has been taught. Not an uncommon fault of private pilots and even instructors I have known.

I am not surprised if he had problems on the PPL theory nav exam. There are 5 questions on radio navigation, and apart from the fact that some of the questions asked have been rather daft, the military tend not to use much radio navigation in elementary training. 48% is rather low, but I suspect he also did little revision and how many of your PPL graduates would do better after a break in training?

My attitude has nothing to do with "it's good enough". Correctly applied by an experienced pilot the MDR techniques are as good as the flight computer. I would not let a new student use them, but a much more experienced or more carefully-trained pilot should be able to use them.

I personally can't see the problem with using MDR. If applied correctly, the "clock code" method gives answers which are close enough to the "whizz wheel" method as makes no difference.

For example, the IR students I train use the clock code method to (very accurately) work out the drift to be applied in holds and on approach procedures.

If we are talking about visual navigation, then the student pilot should also be reading ground-to-map and map-to-ground and therefore the MDR is not the sole navigational reference used.

If it radio aids navigation, then the VOR/DME is used to fix position and again, the MDR is an aid to placing yourself close enough to the desired fix such that appropriate corrections may be made.

Let us also not forget that the 2000' wind used in the nav computer calculations is actually just a forecast - so even though the whizz wheel can calculate drift to 0.000001 of a degree, the information being fed in is just a guess by the met man.

If, upon reaching the first waypoint, the wind assumptions are found to be incorrect, then a correction may be made. If the trainee is used to calculating drift etc. using MDR then this airborne replanning is actually EASIER for him than for the student who relies solely upon the computer.

MDR
 

The Met Man's forecast is more than just a guess! At higher levels it is usually very accurate. At lower levels almost impossible owing to surface factors but averages out quite well.

How do you MDR over the North sea better than using forcasts and applying the same by using the whizz wheel. I understand the arguements of MDR but are you throwing out the baby with the bath water?

I suspect that "out over the North Sea" I might be following a VOR or ADF track most of the time (or RNAV or GPS). Don't recall long, oversea VFR nav legs being part of the training.............

Seriously, I would like to know the %age error incurred when using MDR as opposed to the nav comp. I postulate that any such error is probably offset by the ability of the MDR trained pilot to re-think when the met mans best forecast of the 2000' wind turns out to be a tad inaccurate.

Whizz-wheels, computers and MDR
 

MDR is my favourite nav method as the pilot navigator is forced to get his head round the anti-intuitive way in which wind affects an aircraft's progress over the ground. It's amazing that nearly all text's are full of stuff about getting groundspeeds and headings, time of flight etc using whizz-wheels and computers and how to operate them, but little about the elementary maths and trigonometry that lie at the heart of all aircraft navigation.
The main problem is guessing the wind vector. My plogs prepared the night before a xc were often a waste of time as the wind had obviously changed by the time a flight actually got going. Getting an up-to -date wind vector in flight seems to be something that nobody seems interested in but if you can get that, ie KNOWING that the wind is 20kts from 260 degT rather than going by the 214 which is only a forecast, I would have thought that was an extremely useful bit of information from which the headings and groundspeeds can be worked out by MDR, and should give accurate headings and eti’s.
I designed a bit of kit for this very purpose but it can do the lot ie pre-flight planning and en-route nav as well. It works extremely well.200yds off target in 20 nautical miles in a 70kt microlight. But you have to up-date the wind vector especially at low level.
The other thing I found out by monitoring the wind vector was that a change was often a warning that new weather was on the way. MDR gives the escape route in a worsening situation -- a huge confidence builder on lengthy navex's.
MDR is less accurate than the whizz-wheel but, as has been mentioned, not enough to make any difference in the air. Add in an accurate up-to-date wind vector and it beats any ground-based pre-flight plan hands down.
MDR ought to be in the syllabus. No wonder so many newly qualified PPL's reach for the GPS. Reason. They are uncertain, and lack the confidence to make en- route adjustments unless conditions and terrain allow easy pilotage. At least that was my experience, until I came across MDR, which was never mentioned once in all my time, training for the PPL.
Why is MDR better than the whizz-wheel? MDR tells me, not only that a wind at 45deg to the track produces three quarters of the max drift, but why. The Whizz- wheel only tells me that the drift is such and such. Lose or forget the whizz-wheel, flight computer, GPS, no batteries, electrical failure, press-onitis, low cloud-base, wind vector alters and your on your way to getting lost and making a nuisance of yourself.
Another advantage is speed. You can get the answers in the time it takes someone to get their whiz-wheel out of the flight bag and it’s even faster than a computer where you have to get into the program and print out the results. These devices do the calculations quicker than I can do them, but not if you count the time to bring them into operation, especially in the air.
Nice to know that if everything fails you can still make a good fist of getting to safety, unaided, in an unfamiliar area.
As for over the North sea, if the met conditions were favourable, should be possible, but in anything less, that’s going to be one for the GPS.

Well, I used the trusty old whizz wheel to plan my flight to Old Warden on Sunday. My landing slot was 1120Z, so I knew that to make the overhead at 1115 I was going to have to leave my timing point (WCO) at 1059. Did this, overhead on time, landing would have been spot on - BUT for some ignorant turkey who blundered in without checking, joined downwind ahead of me having clearly not bothered to read the arrival instructions (Overhead join mandatory) and then flew a typical excessively long final!:mad:

The GPS agreed with the whizz-wheel, but it's important to be able to fly the plan even if the GPS dumps. My forecast wind estimate of 230/15 was pretty close - so I stand by accurate pre-flight planning using the most accurate information available being the best way.

It never ceases to amaze me how simple but very important things are overlooked when teaching simple VFR navigation be it the RAF, or civil FTOs.

Countless times I have come across the following situation when dealing with VFR navigation tests or PPL re-training;

A flight is planned from A to B and an alternate is chosen which is either further along in the direction of travel or close abeam the destination.

The pre-flight planning for the diversion is taken from overhead the destination.

I ask the pilot where they will divert to if the visibility and cloudbase at destination are below the required minima. The answer is always to the alternate to which I say......if the weather is below VMC at the destination, how can one overfly or fly past the destination to the pre-planned alternate.

When dealing with diversions due to lowering cloudbase and/or reducing visibility, such a diversion will never take place from overhead the destination because one can't get that far and if one could, one would land. The simple fact seems to be missing from most VFR navigation training these days.

OK blocked runway/ comms failure/ ATC delays and winds are different factors but many pilots expect to use the alternate in every situation.

Thus having some MDR skill is important because when the pilot is placed with the need for a diversion it will be somewhere downroute and the computer is too cumbersome to use in the air at the same time as flying the aircraft and maintaining an adequate lookout in reducing visibility!

IMHO - computer for pre-flight, MDR in-flight.

Regards,

DFC

Quite so, DFC! That's our teaching as well.

Time for a change? IMHO, MDR on the ground using the latest met info ie 214 and observation, to build an approximate picture of the flight.
Into the air and get the actual wind vector at en route altitude using the new kit on the market designed for use in the air.
MDR from there on with updates of the wind vector according to time available and need. Groundspeed and WCA and the kit(no changing of glasses) gives the wind vector in 5-10 secs.
Time moves on, things change, sometimes for the better.
Improvement in the nav kit we use is possible.

Sea no Land.
 

The use of Radio Aids are an addition to basic Nav. The basics of navigation to PPL standard assumes that the aircraft is not fitted with such aids as VOR, DME, ADF or the likes of GPS or that the transmitters are not available. Such well developed root of the art techniques correctly applied work well. The techniques apply whether over the sea, desert or the satilite towns of the home counties and they do not need batteries or generators to function.

That is not to say MDR is wrong. The navigation section of the CPL Skill Test is a section that has the greatest rate of failure. Why - the mistakes are usually silly - well the pilot is under stress. Simple mental arithematic becomes a burden and the visual clues, like a mirage, become what the individual wants them to be, mistakes are made.

It is a fact that there is not a single unpredictable factor that will raise it's head on a flight and it is therefore within the pilot potential to pre-plan for them. Using Forcasts winds and calculation of headings prior to flight using the slide rule and common sense mental arithmetic is part of that philosophy.

Whether or not you are a supporter of MDR, don't thow out the baby with the bathwater! Supported with the basic skills of navigation MDR has a place. Indeed it is currently taught under the heading 'Unplanned Diversion'. Always has been.

UAS flying training is aimed at producing potential fast-jet pilots. At 420 kts (7 nm/min) the effect of drift is very small. You need 70 kts of wind to get 10 degrees of drift! If you think I'm going to get a DC out at 250 ft at that sort of speed you must be mad.

Military navigation is based on the premis of maintaining track and regaining track asap, which is usually your only tactical option. MDR works very well for this. PPL level navigation seems to be based on blindly following a plan adjusted for imprecise winds until you find you are miles off track and then making a correction to achieve your planned turning point. What is the point of planning a route to carefully avoid problems like controlled airspace, resticted areas etc and allowing yourself to wander off track. Any wonder we see so many reports of PPL traffic infringing.

MDR is great for maintaining track. I would rather be on track than blunder into a restricted/danger area. It relies on a basic understanding of the triangle of velocities and provides a quick, simple and acurate (as acurate as the met man's wind forecast) means of getting from A to B. It'll do for me.

No-one is suggesting that you should use a whizz-wheel for in-flight corrections when using pilot navigation.

The effect of drift is far greater at 'PPL' speeds; an accurate pre-flight plan with time at waypoints (exactly as used to be taught at UASs) is flown; corrections are made using, in the main, SCA and proportional timing. MDR is taught for unplanned diversions using clock-face and max drift.

I certainly agree that regaining track by the quickest rigorous means is preferable to flying direct to the turning point from a position miles off-track and blundering into restricted or controlled airspace as a result. Hence we haven't taught the ancient 'track error plus closing angle' based on the 1:60 for years - or the New Track Reference method either, for that matter.

KISS - Plan accurately, fly accurately and think ahead.

I have been taught to navigate both in the EFT system and the PPL way, and one observation I would add is that many civvy flyers plan and fly very long legs. I have always tried to keep the legs somewhat shorter and use good positive fixes - even if it means going out of the way a bit. I know some people will raise the issue of 'feature crawling' with this method, but I do believe that if you have a shortish leg with a decent half-way (or 1/3 and 2/3) position/time fix without long amounts of time in between them, it gives you the confidence and ability to dump the map in between fixes, fly and look out. Your route shouldn't take you that close to restricted areas etc.. that it means you are paranoid about staying exactly on track at the expense of lookout and sortie management.

Blagger

Forgive my ignorance on two counts (at least:) ) but:
- Correctly applied, the Max Drift techniques are as nearly as accurate as the wizz wheel, what's the problem with using them for pre-flight planning as well as in flight?
- What's the "New Track Reference" method?

HFD

Thanking you Hugh Flung Dung for echoing my sentiments with respect to using MDR for pre-flight planning.
What difference does it make if the pre-flight is done by the brain or computer, mechanical or electronic?
As to the "new kit" I referred to in my earlier postings, may I suggest a click on the WWW opposite my name, to get a better idea of where I'm coming from.
All comments adverse or otherwise gratefully received.
System designed by a Scotsman, made by an Englishman and looking for (probably) a Welshman who can talk the knickers off a nun to market it.

AWL: good luck with marketing it - it's a nice idea but I have a personal hate of gadgets. The MDR calcs can be done visually on the face of the DI to any accuracy that you care to use so I don't believe another gadget is necessary.

HFD

A question for you MDR pre-flight planners. Having noted the proportion of max drift to apply for heading correction, do you also apply the head/tailwind component to your planned TAS to obtain a GS? If you do, and the result is something like 103 kts, how do you then calculate the time at a visual fix 17 miles along track? In your head, on your fingers - or with a calculator?

Or do you say "Well, 103 is nearly 105 which is 7/4 miles per minute. 4/7 of 17 is err, umm, seven fours are 28, four tens are 40, so that's 68/7 which is err, a bit under 10 minutes."

Which is a bit gash if you then try to estimate your revised ETA when you are early/late at the 17 mile fix 1/3 of the way along the leg!

Hello Beagle,
In the head. Something like this.
103kts, somewhere between 100kts and 110kts. 100kts factor 0.6. 110kts factor 0.55(the factor is the no. of nmls covered in 1 min.)
17mls,@100kts, time taken =8.5+1.7(0.1 is a 1/10 of 17) = 10.2mins.
17mls@ 110kts then 8.5+ 0.85 (0.05 is 1/10 of 0.5 which is ½ of 17 which is 8.5) = 9.3 mins.
If it takes 10 mins exactly Gspd will be 102kts.
(17 times 60/10 ie times 6=60+42=102). Use this as the base.
In the air. 10 mins=102kts. Shade over 11mins 90kts. 8.5 mins 120kts. Split the difference if accuracy is requd. Ie 10.5mins use 95kts. 9.5mins use 110kts.
Whatever the time taken, double it and add to the real time to get best ETA. if 17mls is 1/3 of the route which continues in a straight line.
Quite a good example, that shows the benefit of doing the MDR for pre-flight planning on the ground. You get an idea of the type of calculations and the sort of figures you’re using in advance, so when you come to do them in the air, you remember and recognise them. The 90kts to 120kts is a tricky area. 90kts is 2/3 or 0.66 and 120kts is 0.5 or ½ and 100kts is 0.6. In the example you gave, you used fractions. Sometimes decimals are easier, sometimes fractions are easier. Use whatever is easiest as accuracy is not paramount. Both can be used. What is required is a facility to switch between fractions and decimals and rounding up and down, something that has been lost in the calculator age.
In navigation, 60 is everywhere. Take 17 mls in 13 mins. If 17mls in 12 mins,17 times 5. If in 15 mins 17 times 4, then split the difference. But that involves three “reckonings.” For me that’s too many.
Using my method, I know that 60/13 =4.6(approx), so 17 times 4.6 = 40+28+9or 10 =78kts. Only one “reckoning”.
Although lots of nos divide into 60, the problems come from the ones that don’t. I’m not usually going to be flying a leg longer than 20mins without a pinpoint. So I’m only interested in the nos that don’t divide into 60 between 1 and 20. These are 7 8 9 11 13 14 16 17 18 19( so near to 20 it can be chucked out
Strangely the nos make an easily remembered sequence.
60/7=8.6
60/8=7.5
60/9=6.6
60/11=5.5
60/13=4.6
60/17 =3.5
As for 14,16 and 18 into 60, they are ½ that of 7,8,9, so 4.3, 3.75 and 3.3 respectively.
The benefit of committing this little table to memory is that you only have to do one multiplication in the air. It’s not super- accurate. There has been fairly liberal rounding up and down, but it meets the requirements for easier DR in the air. For any application there is always a balance between accuracy and speed. In the DR situation speed and facility get priority over accuracy, within limits.
Getting the wind vector can be done mentally but involves about 3 calculations using the 1in 60 rule and
gives the wind angle to the plane. Too much. The plastic gadgets win out on this one. Gspd +WCA, simple up down movement of protractor on Gspd scale and read-off. Simple Triangle of Velocities and very accurate. MDR thereafter, comparing what you thought you would get with what is actually happening.
I’m off to check the GPS still works and give it a chance to up-date the almanack and ephemeris. Great little things. Gives the passengers something to play with, keeps them strangely reassured as to where they are, where they’re going, and most important of all, answers the question( but only based on the current GSpd) “When are we going to get there?" Probably the mindset is "If it's on TV or something that looks like a TV it must be OK." Just a passing thought but may be not a few pilots have the same mindset.

Easiest & quickest method I know:


103 ......... 17 <---- outer scale on a whiz wheel
______________ <---- divisor on a whiz wheel
. / \
/60\ ..........10|| <---inner scale on a whiz wheel


Answer = 10 min

9:54 to be precise. Which is why, as you so ably demonstrated, the whizz-wheel with its analogue scales is so useful and simple for pre-flight planning!

Using MDR, all those 'factors' and inverse 60 times table seems much, much more difficult, error prone and of somewhat nugatory efort. Moreover, errors introduced by MDR pre-flight planning for ETAs mean that it may well be not just the wind which may have caused a time error at the 1/3 leg point, so proportional timing correctio is not valid.

But MDR is fine, absolutely fine, for unplanned diversion work.

9:54 at 103kts compared to 10.00 at 102kts. 6secs and 1kt.
On the day in the air you wouldn't notice the difference.
Unnecessary accuracy for an environment in which too many factors are not able to be measured with great precision.
Going for such accuracy using precision instruments in the pre-flight plan is wasted effort because you are guessing the wind vector. A 5kt, 10 deg error in the wind vector will knock all that accuracy for six, especially at the six second level.
Once I've got the wind vector, that's when I start sharpening on my eta's.
MDR is fine for unplanned diversions. So presumably it won't hurt to use it for planned diversions. That's the way I see it, the whole route becomes a series of planned diversions.
As to the nugatory effort involved with the factors and the mental arithmetic of 60, there is little to learn, and you only have to learn the ones that cover the speeds within 35kts+ and 35kts- of the cruise speed of your aircraft. The factors make the mental arithmetic easier. That's what they're there for. True, they are less accurate than the whizz-wheel but the differences in practice are barely discernible.
On my last navex to the the West of Scotland and the Inner Hebrides, the rate of change in weather meant, that to stay VFR and avoid high ground, going anywhere was a series of diversions. If the MDR is good enough for 1 unplanned diversion then why isn't it good enough for 4 or five planned diversions in series?

I too have a dislike of airborne gadgets, many of which slither about on the CAA's laminated chart and end up on the floor..... But pre-flight planning using the simple old Dalton is a different matter. It takes no more than a minute or so for a triangular route and the forecast wind is normally of sufficient accuracy for a typical 50 mile leg. Then it's 'Heading and time' between pre-planned fixes, correcting heading and ETA estimates by in-flight observation, not re-planning the whole leg after wind-finding which I find something of an over-complication for PPL level navigation. The difference with 'unplanned' diversion flying is that map reading is required to back up in-flight estimates to a somewhat greater extent than on planned legs.

Arrive at the 1/4 way fix with an error of 20 seconds between planned and achieved time would normally require a turning point ETA correction of 80 seconds by conventional proportional timing correction. But if 10 of those seconds were due to 'near enough' MDR planning and 10 were down to the wind, an 80 sec correction would clearly be incorrect. And it doesn't take much more to put you outside the timing error limit acceptable for the PPL Skill Test.

I shall stick to teaching the conventional wisdom of measuring twice and cutting once. Accurate pre-flight planning using the best forecast wind using a whizz-wheel; Standard Closing Angle and Proportional Timing in-flight, MDR using max drift and clock face for diversions, backed up with slightly more map reading (NOT track crawling) during the diversion.

MDR
 

Beagle,

Absolutely correct!

Sorry AWL, that's all a bit OTT - you must see very different PPL studes to mine if they can cope with that;)

I think there's a much simpler way:

• plan your IAS to give an easy TAS such as 90, 100, 120, 150, etc (using IAS=TAS-2% per 1000 ft and -2% per 10 deg above ISA)
• calculate your leg times based on still air and TAS (2/3, 0.6, 0.5, 0.4, etc)
• modify the leg time based on the head/tail wind component percentage of TAS.

In other words:
Flying at 3000ft at ISA, 120TAS = approx 115IAS.
Still-air time is now 0.5 x distance
If flying into a 10kt HWC the leg time is increased by about 8%

So, if the distance is 40 miles the estimated still air time is 20 mins and the estimated time with wind is 20+8% = 21.6 mins.
By CRP5: time = 21.8 mins.
QED

I think the wizz wheel is a great device but lots of PPLs don't seem to bother with it; also, if MDR isn't practised regularly they are unlikely to be able to use it if they need to divert. People need a way of visualising the effect of the wind and a simple set of rules with minimal sums. Any assessments should be based on simple visual proportions of known values whenever possible (eg using the DI as an "analogue computer" to <calculate> the proportion of max drift, head/tail wind components and crosswind components).

Beagle: What's the "New Track Reference" method that you mentioned? I can't recall anything of that name.

HFD

1. There should be no need to use the word 'about' in pre-flight planning. Exact calculations should be made.

2. The NTR method I have consigned to the trash can of memory. I vaguely recall that an observed angular error was multiplied by the reciprocal of the proportion of track flown since the last known fix, or something like that. Too much hard in the way of hard sums - and excess error from incorrect assessment of observed angular errors.

Why are so many people so seemingly wary of teaching the basics of the whizz-wheel? It's hardly difficult - I learned it at 16!

The idea of planning an IAS to make the TAS 'easy' is a new one on me. OK - on Hunters I used to fly at M0.8 plus or minus the headwind, so it was somewhere between .75 and .85 most times so that 8 miles a minute could be used for rough calcs, but a light aroplane has a very restricted range of IAS. To teach students to set an RPM which would give 96 KIAS is a waste of time - just fly at the correct cruising speed having spent a few minutes with the whizz-wheel prior to flight.

There seem to be two types of navigation under discussion, yours for teaching the PPL and mine for after the PPL. Yours is based on an accurate flight plan which is modified if necessary by adding bits on or taking them off the computed figures in response to changing conditions and that should be fine for a triangular route lasting 1.5-2hrs, but for a 200-300 ml navex with varied weather?
Mine is less accurate at the planning stage, but only because I deliberately use MDR to get the practice. But that changes in the air with the ability to get an accurate up-to date wind vector. Instead of modifying existing calculations, you do them again using MDR, or the instruments will give you the relevant heading and groundspeed, to get to the next waypoint. Thanks to the new, large clear design (which gives. a visual appreciation as well as a quantitative evaluation of the wind vector) repetition and monitoring of the wind vector is an easy task. Yes you have to fiddle with the instruments, but at least they are easy to fiddle with, unlike the Dalton and they measure distances and bearings on the map.
Point taken about MDR for learners. I suppose they’re near overload at the testing stage but later on?
Just daring to try something new in the conservative area of aeronautical navigation, a last attempt to modernise the traditional methods before they collapse under the onslaught of GPS.
Thanks for the comments and info. It’s given me a few things to think about.
AWL

One other point. Who in their right mind would use a GPS to derive a wind and then use that with MDR methods to refine a plan? If they've got a GPS, all they'd need to do would be to cross-check DTK and ETA values with the pre-flight calculated values, then keep the CDI centred and enjoy the view!

And why not, indeed!

Ermmmmm - because it is not a legal way of navigating, perhaps? Or because it causes drastic loss of situational awareness, and the CAA at least blame this attitude for the recent increases in airspace infringements?

I agree that correcting heading by the track error given by GPS and using the ETA function is better than MDR for that leg. However what if the GPS does not have a signal for the next leg? At least the person you refer to would have a wind more accurate than the forecast, if a little out of date. He also keeps in pracdtice with his MDR for use when it is really needed.

Beags: If I understand your comment about NTR it's to take reciprocal of fraction gone and multiply it by closing angle to regain track at destination - not exactly "new", although I guess it depends on your vintage:) - I'm a '53; a particularly good year (BTW, my formative years were spent in Lincoln, flashing morse code message to the Vulcans from my bedroom window - why didn't you write down the address and visit?). This is the method that's currently in vogue in a number of schools (including mine) and I don't like it. Since so much time was dedicated to studying the planned track it seems such a shame not to get back onto it at the earliest opportunity rather than at the destination. SCA seems a good way of doing it (although my boss (ex- groupie TP) is adamant that it doesn't work at GA speeds) or simply to double the error to regain track at double the distance gone.

Accuracy is laudible if it's to do with nuclear safety or something else where all parameters are accurately know. Pretending to calculate headings and times to the nth degree in aviation is pointless, it's a bit like the GCSE candidate writing down all 24 digits from the claculator having used a series of approximate parametric measurements as inputs. "Garbage in garbage out" comes to mind.
The wind is approximate, the IAS is approximately flown, the height is maintained approximately and the track may require minor tweaks. I suggest that 21.6 vs 21.8 minutes is pretty damn good, especially if the stude then has a picture of what's going on rather than a series of meaningless headings and times without a "picture".

Please don't misunderstand - I teach and (almost) praise the wizz wheel but, post-PPL, the evidence is that many people don't use it and rely on the great god of GPS (a wonderful tool but doesn't help with the big picture). In my day job (that's giving the game away a little) part of my role is to innovate and to think outside the box. Applying that to GA: why shouldn't we work backwards and set the IAS to give an easy TAS? Why do we have to force people to use a device that they don't use after the exams? Why do we have to teach slide rules to people who haven't even heard of log tables and who don't know about geometric series or how electronic calculators work? Why do we have to teach one method for planned Nav and a different method for unplanned Nav (which, BTW, they won't need to use for 4 years post-PPL and by then will have forgotten)?
The way we teach people to fly was set down nearly 90 years ago - maybe we should re-think a couple of areas in light of educational and technological changes.

I hope this makes sense when I read it tomorrow, after the wine has dissipated.

HFD