Crp-5
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Join Date: Feb 2002
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In answer to EGBKFLYER:
There are 3 main applications of the CRP-5 in JAA exams:
1) You have measured the track (course) off the map, you know the TAS you wish to fly, and you have a forecast wind.
2) You are flying a heading (for instance, a mandatory radar heading), you know your TAS, and you have a forecast wind.
3) You know your heading (after all,you're the bloody pilot - you should know that - you're flying it). You know the TAS - you've done some work during the flight planning process. You can find your track and groundspeed - either you pass over 2 successive fixes and you use them to find your track and groundspeed, or you've got INS, or (if it's a very old aeroplane) - you've got doppler. So now you've got heading and TAS and track and GS. Using the CRP-5 you can now find a wind. This will be more recent and more local than your met met forecast.
(Look - I know some of this stuff sounds a bit old-fashioned - but I don't write these exam papers - I just prepare students to answer them - OK?)
You will find an equal amount of all 3 types of the above questions above in the average JAA exam. If you want to pass - then you have to be equally good in answering all 3 types of question - because you can expect about 8 of each type to turn up in the exam. Do you want to throw the exam away because you haven't prepared 8 of the 24 of this type? As Dirty Harry says - do you feel lucky, punk?
No. So any sensible bloke (or girl) who wants to pass this exam will get equally good at all 3 types of question.
THE ONLY WAY TO DO THAT IS WIND DOWN!!!!!!! Otherwise you have to learn wind up technique for finding heading from a known track, you can (just) by bodging it, find W/V from wind up, but there is NO neat and easy way for finding track from heading from wind up.
Honestly, guys and girls - use wind down technique for all 3 problems - it's so much easier, once you get used to, it works for all the problems, and it's consistent. Wind up method is only suitable for PPLs who are not going to go on to CPL or ATPL and only need to be able to find heading, given track. But it's useless for the other 2 problems - WHICH YOU WILL NEED TO BE ABLE TO DO EQUALLY WELL IF YOU WANT TO BECOME A CPL OR ATPL!!!!
Sorry about the capitals, but I see so many stupid opinions on this subject, and I haven't come to these conclusions lightly.
There are 3 main applications of the CRP-5 in JAA exams:
1) You have measured the track (course) off the map, you know the TAS you wish to fly, and you have a forecast wind.
2) You are flying a heading (for instance, a mandatory radar heading), you know your TAS, and you have a forecast wind.
3) You know your heading (after all,you're the bloody pilot - you should know that - you're flying it). You know the TAS - you've done some work during the flight planning process. You can find your track and groundspeed - either you pass over 2 successive fixes and you use them to find your track and groundspeed, or you've got INS, or (if it's a very old aeroplane) - you've got doppler. So now you've got heading and TAS and track and GS. Using the CRP-5 you can now find a wind. This will be more recent and more local than your met met forecast.
(Look - I know some of this stuff sounds a bit old-fashioned - but I don't write these exam papers - I just prepare students to answer them - OK?)
You will find an equal amount of all 3 types of the above questions above in the average JAA exam. If you want to pass - then you have to be equally good in answering all 3 types of question - because you can expect about 8 of each type to turn up in the exam. Do you want to throw the exam away because you haven't prepared 8 of the 24 of this type? As Dirty Harry says - do you feel lucky, punk?
No. So any sensible bloke (or girl) who wants to pass this exam will get equally good at all 3 types of question.
THE ONLY WAY TO DO THAT IS WIND DOWN!!!!!!! Otherwise you have to learn wind up technique for finding heading from a known track, you can (just) by bodging it, find W/V from wind up, but there is NO neat and easy way for finding track from heading from wind up.
Honestly, guys and girls - use wind down technique for all 3 problems - it's so much easier, once you get used to, it works for all the problems, and it's consistent. Wind up method is only suitable for PPLs who are not going to go on to CPL or ATPL and only need to be able to find heading, given track. But it's useless for the other 2 problems - WHICH YOU WILL NEED TO BE ABLE TO DO EQUALLY WELL IF YOU WANT TO BECOME A CPL OR ATPL!!!!
Sorry about the capitals, but I see so many stupid opinions on this subject, and I haven't come to these conclusions lightly.
Supercharged PPRuNer
Join Date: Nov 2000
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We had remarkably similar advice from BGS. 
I managed to finish General Nav 5 minutes before the end - a lot of people didn't even finish it. I'd take two messages from that:
(1) You need to be able to work very quickly.
(2) You need to get the right answer - first time - because you certainly won't have time to go back and check everything.
To do this, you absolutely must be comfortable with the CRP-5. There is no way round it.
I managed to finish General Nav 5 minutes before the end - a lot of people didn't even finish it. I'd take two messages from that:
(1) You need to be able to work very quickly.
(2) You need to get the right answer - first time - because you certainly won't have time to go back and check everything.
To do this, you absolutely must be comfortable with the CRP-5. There is no way round it.
When - and that's an 'only if my Jepp CR type isn't handy - I use a slide type whiz wheel, I prefer wind up for the standard 'find heading & GS' planning problem, and wind down for the others. I can do it the other why but why have to buggerise around shuffling the disk when 'wind up' gives the answer directly?
It's not difficult to remember. Of course it equally possible to learn to use wind up ALL the time. There is NO mathematical difference in the technique. But in general I prefer the method with fewer iterations, no matter whether it's wind up, or wind down.
Even better, get a CR type...
It's not difficult to remember. Of course it equally possible to learn to use wind up ALL the time. There is NO mathematical difference in the technique. But in general I prefer the method with fewer iterations, no matter whether it's wind up, or wind down.
Even better, get a CR type...
Join Date: Oct 2002
Location: UK
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Blue, got to go with you! Who would want to use a method that would provide some of the answers, but not all. Nav instructor (Sharp) would have beheaded anyone using "wind up: method. That's for Americans 'cos they don't know better.
For any Nav student, mastery of the CRP5 is essential - Fflight Planning, Met, Instruments, it's great!! it's not cheating and gives all the answers.
The word is PRACTISE!!!!!!
For any Nav student, mastery of the CRP5 is essential - Fflight Planning, Met, Instruments, it's great!! it's not cheating and gives all the answers.
The word is PRACTISE!!!!!!
Seems it's not the Americans who are ignorant. Wind up is perfectly capable of providing all the answers if you wish. Mathematically its the same triangle. You miss the point: Why use a method that requires iterations to derive the answer when there's a method that gives it directly? 
But then the 'ignorant Americans' tend towards the CR type which is simple to use for pretty much all problems, can solve a greater variety of problems AND in some cases requires fewer steps to calculate an answer than the CRP. It even fits in a pocket...
But then the 'ignorant Americans' tend towards the CR type which is simple to use for pretty much all problems, can solve a greater variety of problems AND in some cases requires fewer steps to calculate an answer than the CRP. It even fits in a pocket...
Last edited by Tinstaafl; 29th Oct 2004 at 02:31.
