Navigation Woes...
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Navigation Woes...
Hi all
Looking for advice on the nav exam and studying for it. I have both the Pratt and Thom series of books and seem to be able to understand the majority of stuff therein. My problems lie within the mathematics and use of the whizz wheel.
The regular operations of addition etc I can manage no problem and if I do the gross error checking on conversions etc they usually turn out close - if not spot on - to the worked examples or questions from the confuser.
My problem lies with the wind calcs. I have been using the wind-down method as I was (or hopefully still) planning on going on to the ATPL/CPL afterwards and noted from previous threads that this was the preferred method. I am also using the CRP-5 to avoid the need to upgrade for later studies!
If I draw the information that is given out on paper to "validate" my thoughts I get close to the correct answers but fail to understand the final jiggle to get the G/S & Hdg..
Any information advice etc is appreciated.
I have been considering the purchase of another book or two that I have seen in the Transair catalog (cannot for the life of me remember their titles) that take you through a complete flight and show alternative methods of doing the calcs - would they help clear the mists?? (Met is another story!!)
Cheers
Dave
Looking for advice on the nav exam and studying for it. I have both the Pratt and Thom series of books and seem to be able to understand the majority of stuff therein. My problems lie within the mathematics and use of the whizz wheel.
The regular operations of addition etc I can manage no problem and if I do the gross error checking on conversions etc they usually turn out close - if not spot on - to the worked examples or questions from the confuser.
My problem lies with the wind calcs. I have been using the wind-down method as I was (or hopefully still) planning on going on to the ATPL/CPL afterwards and noted from previous threads that this was the preferred method. I am also using the CRP-5 to avoid the need to upgrade for later studies!
If I draw the information that is given out on paper to "validate" my thoughts I get close to the correct answers but fail to understand the final jiggle to get the G/S & Hdg..
Any information advice etc is appreciated.
I have been considering the purchase of another book or two that I have seen in the Transair catalog (cannot for the life of me remember their titles) that take you through a complete flight and show alternative methods of doing the calcs - would they help clear the mists?? (Met is another story!!)
Cheers
Dave
Why do it if it's not fun?
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Dave,
The "wind down" method tells you what drift you will get if you fly a particular heading. You need to "jiggle" to get the wind for the desired track.
Let's take an example. (N.b. I don't have a CRP5 to hand, so I'll make up numbers which are approximate - you will probably get different numbers if you actually work through my example!)
In our example, the wind is 300@20, you intend to track 270 at 90kt. You use the "wind down" method, and find that, if you fly heading 270, you will have 14 degrees of drift, suggesting a heading of 284.
Now, the jiggle: repeat the process, but this time, instead of 270, work out the drift for heading 284. You find that the drift is now 12 degrees. (The reason for the reduction is because you've turned into wind slightly, so there is slightly less crosswind than there was on the heading of 270.)
Ok, so if the drift is now 12 degrees, we need to jiggle again, and try a heading of 282. On that heading, we still have a drift of 12 degrees, which confirms that 282 is indeed the correct heading.
Hope that clears up the jiggle.
FFF
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The "wind down" method tells you what drift you will get if you fly a particular heading. You need to "jiggle" to get the wind for the desired track.
Let's take an example. (N.b. I don't have a CRP5 to hand, so I'll make up numbers which are approximate - you will probably get different numbers if you actually work through my example!)
In our example, the wind is 300@20, you intend to track 270 at 90kt. You use the "wind down" method, and find that, if you fly heading 270, you will have 14 degrees of drift, suggesting a heading of 284.
Now, the jiggle: repeat the process, but this time, instead of 270, work out the drift for heading 284. You find that the drift is now 12 degrees. (The reason for the reduction is because you've turned into wind slightly, so there is slightly less crosswind than there was on the heading of 270.)
Ok, so if the drift is now 12 degrees, we need to jiggle again, and try a heading of 282. On that heading, we still have a drift of 12 degrees, which confirms that 282 is indeed the correct heading.
Hope that clears up the jiggle.
FFF
-----------------
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Never heard of the Wind-Down method. I just read track off the GPS and alter my heading until actual track = desired course over ground 
For flight planning I use Flight Star
For flight planning I use Flight Star
englishal
only one slight flaw in your cunning plan, you cant use that method in the exam!
RudeNot2: FFF has the answer
Ken
I just read track off the GPS and alter my heading until actual track = desired course over ground
RudeNot2: FFF has the answer
Ken
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Eek
Never heard of the Wind-Down method. I just read track off the GPS and alter my heading until actual track = desired course over ground For flight planning I use Flight Star
For flight planning I use Flight Star
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Wind down cd
Get the Nav and CRP-1 OAT CD ROM.
I Know you're using the CRP-5 but the cd rom really is excellent for visually and verbally explaining how to carry out all necessary calcs on your flight computer.
Don't buy any more books, I'm confident that this'll do the trick.
Good luck
Nadders
I Know you're using the CRP-5 but the cd rom really is excellent for visually and verbally explaining how to carry out all necessary calcs on your flight computer.
Don't buy any more books, I'm confident that this'll do the trick.
Good luck
Nadders
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I will 2nd what nadders said. I had the same problem, once I could follow it through, it was a piece of cake,
Not used it since my NAV exam, tend to use mental arithmatic, and work it out as and when I need to
But gonna have to start using it for my IMC exam
Not used it since my NAV exam, tend to use mental arithmatic, and work it out as and when I need to
But gonna have to start using it for my IMC exam
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Start with your vision of the triangle of vectors on paper. Point A - the aeroplane, is at the bottom (usually off the bottom), of the sliding scale (in the middle, where the zero speed would be).
The centre of the rotating circle can be either point B (the end of your TAS and Heading) or point C (the end of your track and groundspeed).
You choose which of these it wil be. When you draw the wind vector Up you are making the centre point C, when you draw the wind vector Down, you are making the circle centre point B.
The usual situation is you know your track (orientation line A-C) and your TAS (length vector A-B), but you don't know the length of A-C and you don't know the orientation of A-B.
Using the Wind Up method means your circle centre is point C of the vector triangle. The END of the wind vector (where the wind blows from) is point B of your vector triangle . You know the track you want to fly, so set it on the outer ring - the wind vector moves about, left or right. You know your TAS, so slide the speed scale up/down until your TAS is under the point B (start of the wind vector). You now have your vector triangle - point A (at the bottom of the scale), point B (the end of the TAS vector) and point C (the circle centre) being the Groundspeed vector. Now just read off your drift on the left/right degrees of the sliding scale, and your groundspeed under the centre circle. No fiddling required.
The fiddling comes with the Wind Down method because you are placing the end of your TAS vector in the centre (point B), from which you have to find out what drift will give you your desired track (point C). As you rotate the circle back and forwards, the drift changes, and so does the eventual track. You are trying to find the correct amount of drift that will produce the track you want to fly. That's what the fiddling is about - matching the drift on the scale, so that it will give the desired track from the selected heading. Finally, once the amount of drift gives the desired track, you can read your ground speed from under the end of the wind vector.
To visualise it all draw a (large-ish) vector diagram (random, TAS, random wind, random track), using the speed scale of the CRP your sepeed, then put you CRP over it - it then becomes more evident.
GB
The centre of the rotating circle can be either point B (the end of your TAS and Heading) or point C (the end of your track and groundspeed).
You choose which of these it wil be. When you draw the wind vector Up you are making the centre point C, when you draw the wind vector Down, you are making the circle centre point B.
The usual situation is you know your track (orientation line A-C) and your TAS (length vector A-B), but you don't know the length of A-C and you don't know the orientation of A-B.
Using the Wind Up method means your circle centre is point C of the vector triangle. The END of the wind vector (where the wind blows from) is point B of your vector triangle . You know the track you want to fly, so set it on the outer ring - the wind vector moves about, left or right. You know your TAS, so slide the speed scale up/down until your TAS is under the point B (start of the wind vector). You now have your vector triangle - point A (at the bottom of the scale), point B (the end of the TAS vector) and point C (the circle centre) being the Groundspeed vector. Now just read off your drift on the left/right degrees of the sliding scale, and your groundspeed under the centre circle. No fiddling required.
The fiddling comes with the Wind Down method because you are placing the end of your TAS vector in the centre (point B), from which you have to find out what drift will give you your desired track (point C). As you rotate the circle back and forwards, the drift changes, and so does the eventual track. You are trying to find the correct amount of drift that will produce the track you want to fly. That's what the fiddling is about - matching the drift on the scale, so that it will give the desired track from the selected heading. Finally, once the amount of drift gives the desired track, you can read your ground speed from under the end of the wind vector.
To visualise it all draw a (large-ish) vector diagram (random, TAS, random wind, random track), using the speed scale of the CRP your sepeed, then put you CRP over it - it then becomes more evident.
GB
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Quote:
Never heard of the Wind-Down method. I just read track off the GPS and alter my heading until actual track = desired course over ground For flight planning I use Flight Star
What are you going to do if your GPS fails ?
Never heard of the Wind-Down method. I just read track off the GPS and alter my heading until actual track = desired course over ground For flight planning I use Flight Star
What are you going to do if your GPS fails ?
I feel another heated GPS debate coming on.....
Show me a pilot who can hand fly and operate the CRaP 5 and I will show you a man with more arms than an octopus.
Thanks god for the ASA flight computer!!
Blah Blah Blah
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Originally Posted by bose-x
Look at the stanby battery powered GPS that has been on charge from the mains power.
I feel another heated GPS debate coming on.....
Show me a pilot who can hand fly and operate the CRaP 5 and I will show you a man with more arms than an octopus.
Thanks god for the ASA flight computer!!
I feel another heated GPS debate coming on.....
Show me a pilot who can hand fly and operate the CRaP 5 and I will show you a man with more arms than an octopus.
Thanks god for the ASA flight computer!!
I prefer good ole nav for vfr, heading distance time and visual references. I do use a GPS in the PA32 sometimes, usualy in crap weather. If not VOR's DME's and NDB's.
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No genuine pilot can pretend to be able to use the circular slide rule in flight, unless he has an autopilot.
And if he has an autopilot, he obviously hasn't had a total electrical failure, in which case why not use the alternatives to GPS e.g. VOR/DME/ADF or even (dare I say it) call up ATC and ask for vectors or whatever. Of course anybody flying somewhere for real will just refer to the 2nd GPS (which will be running anyway) and get on with the flight.
This stupid device exists for the same reason as you need to wear a certain kind of pullover when playing cricket, or wear a leather apron in a masonic lodge, or the soldiers guarding Buckingham Palace wear those silly high furry hats, etc - it's a great olde English (note: not "British") tradition which usefully separates the men from the sheep.
I am rather suprised it is mandatory at the JAA ATPL level, since no airline pilot young enough to be currently serving will have ever used one for real. In the commercial air transport world, this stuff went out with the sextant. I hope that nobody flying jets for real actually believes otherwise; I would be seriously concerned for my safety if they did.
The FAA doesn't require it in the PPL, CPL, ATPL and guess what, all these are ICAO compliant. To top this insult to our regulators, most of the world flies under FAA licenses!! I just hope the Daily Mail never finds out.
To answer the original poster's Q I would suggest learning it just enough to pass the exams, and sell it on Ebay immediately afterwards.
And if he has an autopilot, he obviously hasn't had a total electrical failure, in which case why not use the alternatives to GPS e.g. VOR/DME/ADF or even (dare I say it) call up ATC and ask for vectors or whatever. Of course anybody flying somewhere for real will just refer to the 2nd GPS (which will be running anyway) and get on with the flight.
This stupid device exists for the same reason as you need to wear a certain kind of pullover when playing cricket, or wear a leather apron in a masonic lodge, or the soldiers guarding Buckingham Palace wear those silly high furry hats, etc - it's a great olde English (note: not "British") tradition which usefully separates the men from the sheep.
I am rather suprised it is mandatory at the JAA ATPL level, since no airline pilot young enough to be currently serving will have ever used one for real. In the commercial air transport world, this stuff went out with the sextant. I hope that nobody flying jets for real actually believes otherwise; I would be seriously concerned for my safety if they did.
The FAA doesn't require it in the PPL, CPL, ATPL and guess what, all these are ICAO compliant. To top this insult to our regulators, most of the world flies under FAA licenses!! I just hope the Daily Mail never finds out.
To answer the original poster's Q I would suggest learning it just enough to pass the exams, and sell it on Ebay immediately afterwards.
Blah Blah Blah
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Originally Posted by IO540
To answer the original poster's Q I would suggest learning it just enough to pass the exams
However I would not sell it or stop using it until you have your ATPL's out of the way and have a job on a commercial flight deck.
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The last time you will use a Crap wheel as a PPL is the PPL exams. The last time you will ever use it as a wannabee ATPL is the ATPL exams. You will never use it in reasl life. Airline pilots don't even do there own flight planninbg it is done by ground ops. You just get in, press the same buttons and fly the same old routes, waiting to spring into action and do the good stuff if the **** hits the fan.
The CRP computer is a piece of history that should be dumped in the compost of aviation history. I don't believe anyone can safely operate a GA aircraft auto pilot or not and operate the CRP. It is a device that takes a lot of heads in time. Time that you should be looking out the window and carrying out see and avoid. The ASA electronic verision is marginally faster to operate but the same comments still apply. This is the reason why we have so many rules of thumb. Safety first.
The CRP computer is a piece of history that should be dumped in the compost of aviation history. I don't believe anyone can safely operate a GA aircraft auto pilot or not and operate the CRP. It is a device that takes a lot of heads in time. Time that you should be looking out the window and carrying out see and avoid. The ASA electronic verision is marginally faster to operate but the same comments still apply. This is the reason why we have so many rules of thumb. Safety first.
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IO540 and Bose et al.
Well I must be an exception to the rule. I am ATPL and I have not one grey hair - I may even be young enough to be your offspring. I still carry the wheel and use it. A damned fine instrument it is too. Yes, there are more modern alternatives that are perfectly adequate, but so is the wheel. You pays your money and takes your choice.
In fact I am not an exception to the rule - all my colleagues carry a wheel and use them.
Well I must be an exception to the rule. I am ATPL and I have not one grey hair - I may even be young enough to be your offspring. I still carry the wheel and use it. A damned fine instrument it is too. Yes, there are more modern alternatives that are perfectly adequate, but so is the wheel. You pays your money and takes your choice.
In fact I am not an exception to the rule - all my colleagues carry a wheel and use them.
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I am curious droopy, tell me what exactly you and your colleagues do with the whizz wheel? Solve Sudoku problems with it?
Not one airline pilot I know uses a whizz wheel anymore so you have really piqued my interest as to what you can possibly do with one!!!
Not one airline pilot I know uses a whizz wheel anymore so you have really piqued my interest as to what you can possibly do with one!!!
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I don't need a Wizz wheel - If I need to calculate drift, I simply take Sin of relative wind to give me a cross and headwind component then add that to my course to give me GS and course to steer...
Of course the Log Tables I use are JAR-FCL approved log tables.
If GPS 1 fails, I use GPS2. If that fails I use VORs. If there are no VORs I use NDBs. If there are no NDBs I may use Atlantic 252 or some other station in Newfoundland....
Of course the Log Tables I use are JAR-FCL approved log tables.If GPS 1 fails, I use GPS2. If that fails I use VORs. If there are no VORs I use NDBs. If there are no NDBs I may use Atlantic 252 or some other station in Newfoundland....
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Yes I am ATPL(H). Two crew, IFR, scheduled type flying in a stabilised but non autopilot aircraft. We do have a (notice the singular) GPS which is approved as a primary nav aid in certain scenarios. We do use flight planning software at base. I am not anti modern stuff and would use it by preference. But there are times (like when the network crashes at work - not uncommon) when the wheel is dragged out. Similarly, on the odd occasion the GPS does throw a wobbly we use it in flight. More commonly we use a wheel to plan subsequent flights on return legs. Yes there is a GPS sat there, but to be quite honest it is often less hassel to use the wheel and not substantially slower.
Don't write off the wheel. It is an incredibly powerful tool and alot easier to use than is made out - practice makes perfect! There are even things it can do that our GPS cannot, like work out intercepts for moving way points (ok I agree that is not terribly useful).
Gadgets are great, but it doesn't mean the old stuff doesn't work. We still often fly IFR with no HSI, no Autopilot and no second GPS and we still get home on time.
Bose,
Not that we have a chance to do Suduko puzzles, but how do you use the wheel to solve them?!!
Don't write off the wheel. It is an incredibly powerful tool and alot easier to use than is made out - practice makes perfect! There are even things it can do that our GPS cannot, like work out intercepts for moving way points (ok I agree that is not terribly useful).
Gadgets are great, but it doesn't mean the old stuff doesn't work. We still often fly IFR with no HSI, no Autopilot and no second GPS and we still get home on time.
Bose,
Not that we have a chance to do Suduko puzzles, but how do you use the wheel to solve them?!!