View Full Version : CPL Navigation Techniques
15th Dec 2004, 19:23
Hi Guys 'n Gals
Just started my CPL course and im about to do the first navigation lesson.
What is the accepted methods to be used in order to get from A to B??
What is the easiest way to get back on track??
Am I correct in saying, for example, if you get off track by the 1/2 way point, you need to get back on by the 3/4 way point??
Would be nice to hear your methods and views on this!
Thanks in advance!
16th Dec 2004, 00:29
The Event Technique
Pre-plan known events for your first leg eg a noticeable town, a multiple track railway and road crossing, a disused airfield etc
Using your pre-planned GS work out when they should turn up
You can then find out if your are running early or late
For every NM off track turn through a fixed angle dependent on your a/c TAS and hold this hdg for 1 min for every 1 NM off track
eg. If you are off track by 3 NM hold the hdg change for 3 min then turn back on wind adjusted hdg
how much should the angle be?
60 / TAS (in NM per min)
eg for an Arrow: 60 / 2 = 30 degrees
keep watching events come up every 3 min and to be honest you should not go off track
in the intervening 3 min chk hdg, alt, ias, t+p etc
this may sound hard or a bit mathematical but when demonstrated just once in the air my students at all licence levels pick it up and see its virtue
16th Dec 2004, 03:01
Unless there's an obstacle (physical or airspace) in the way, why do you want to get back "on track"?
You said that you wanted to go to 'B' - so, when you work out where you are, turn direct to B.
16th Dec 2004, 09:04
If my experiences are typical, your school will have an "approved" method of navigation, and you will have to follow their techniques.
It is important to realise that there are a number of different ways of navigating visually. All of them are valid, all have their plus points and their minus points. But for the purpose of your CPL, none of this matters at all - the only thing which matters is the "approved" method.
You might find it useful to read my CPL diary (http://www.pprune.org/forums/showthread.php?s=&threadid=108385) - this was all discussed at some length there.
16th Dec 2004, 15:31
I understand that you are an examiner for the CPL over in Florida, are you not?!
So basically, during the skills test, even if the FTO I was training with wants a certain method applied to get back on track, I can actually use any way I like to get to B?
For some reason I was under the impression that you needed to get back on track by the 1/2 way point, if you were off track at the 1/4 way point!!??
Thanks for the info FFF ! Will read it!
16th Dec 2004, 16:12
Hasn't your training provider given you a copy of Standards Document 3? If not, then it's not much of a provider! You can download a copy from the PLD website. It says, among other things -
Section 3 is usually flown after Departure to ensure an efficient flow to the flight. During this section of the flight the aeroplane is assumed to be on a passenger carrying operation under Visual Flight Rules. When the aeroplane has achieved cruising altitude, normal cruising speed and is on heading for the first destination, the applicant should confirm to the Examiner the heading, altitude, and ETA, thereafter advising any changes. For example, "2 minutes late at my halfway point - the revised ETA is now. . ." Corrections to heading or ETA shall be calculated rather than based on track crawling, impulse or inspiration. The applicant is expected to navigate by visual positioning in a practical way, not to feature crawl. Numerous heading or altitude changes that are the result of poor flying may constitute a fail in this section. The applicant is expected to make changes to his heading and ETA in order to correct deviations from his plan. Radio navigation aids may not be used during the first leg of the en-route section although they may be tuned and identified in anticipation of their use later in the flight.
Other than that, there is no 'right' or 'wrong' way provided that you reach and correctly identify your destination.
16th Dec 2004, 17:20
Use the search function. You'll find lots of threads about navigation techniques. On the day of the test you can use any acceptable method you like - they all eventually achieve the same result of getting you to your destination.
I favour 1:60 but have used others when appropriate, BEagle is a staunch advocate of 'standard closing angle' & nothing else, others like pre-drawn drift lines etc. As FFF says, they all have advantages & disadvantages. I'd suggest you should try to become reasonably adept at a range of techniques. They all add to your toolbox of skills, able to be used when appropriate.
Commercially, you wouldn't bother trying to get back on track unless there was some compelling reason eg airspace, terrain, weather or dearth of subsequent nav. features once back on track. Usually you'd try to track direct to the destination.
17th Dec 2004, 20:46
So guys ... sorry for being so thick, but is this correct then ... ?
If not on track by the 1/4 way point = adjust with double track error and at 1/2 way point make a correction.
If not on track at the 1/2 way point = tripple track error - make correction at 3/4 way point.
If not on track at 3/4 way point = add TE + CA to get to the destination.
Am I correct here?
Would I be able to navigate accurately using this method ?
Thanks and sorry again .... to used to track crawling!!
17th Dec 2004, 22:36
2 x TE at 1/4 way point: This gets you back on track at the 1/2 way point. Note that the 'secon TE' is really the CA for the 1/2 way point. Once on track at the 1/2 way point the adjustment then needed to maintain track will be to remove the CA part of your off track correction.
If you're not on track at the 1/2 way point you could use 3 x TE to get back on track by the 3/4 way point. In this case the CA that will need to be removed once on track is 2 x TE. You could also do a 2 x TE to get resume track at the destination.
Don't forget you can always add TE + appropriate CA to arrive at a given point eg destination, or any other point you choose.
18th Dec 2004, 09:32
The reason I advocate SCA is because it is sooooo simple! There is only one number to remember and no tricky sums to do in your head.
Agree that correcting a track error 'commercially' would normally mean requesting a 'direct' to the next turning point. Frequently, when vectored around slower traffic and subsequently recleared 'own navigation', I would always ask for such a 'direct'...
But on a VFR route in lower airspace, if you don't get back onto your planned track reasonably quickly, you may not see your subsequent pre-planned fixes if the visibility is other than good.