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 Professional Pilot Training (includes ground studies) A forum for those on the steep path to that coveted professional licence. Whether studying for the written exams, training for the flight tests or building experience here's where you can hang out.

 30th Dec 2012, 11:40 #221 (permalink) Join Date: May 2001 Posts: 10,858 Its all to do with the output. I suspect you haven't got the basic concepts abouts whats going on. All About Circuits : Free Electric Circuits Textbooks Try reading through that a bit and see if you can work it out yourself. If you really get stuck just ask. Power factor is the interesting bit
 3rd Jan 2013, 17:01 #222 (permalink) Join Date: Jun 2012 Location: GMT+2 Posts: 23 Va and Vno-when to use each Happy New Year to Everyone. Have been studying the limitations chapter in POF and in particular, the V-n diagram that deals with the load factor limits of the flight envelope, and the various important speeds that you find on that envelope. Comparing the definitions of both Design maneuvering speed (Va) and Max Structural cruising speed (Vno), I am a bit confused. I would like to know what exactly is Vno useful for? I understand it is the limit above which flight should be attempted in smooth air only (no turbulence?) and then only with caution. Why is it then that everywhere else I read, it says that when encountering turbulence you should slow down below maneuvering speed, in addition to when you are engaging in maneuvers, etc. I am aware that the definition of Va is often a varied one and commonly misunderstood by many pilots, usually along the lines that you think you are guaranteed in throwing unlimited abuse at an airplane thru abrupt control deflections, etc without having it fail as long as you are below Va, so I am not inviting to dissect this subject unless necessary in answering this post. So based on the definitions from aviation textbooks of what each speed is, I'd simply like to know which one should be used for what then and why? I too would think Va is the more important one, since it deals with protecting the airframes structural integrity, but then I also been in many an airliner that when it has experienced turbulence, I've never perceived it to slow down a substantial amount as if it was aiming for a speed below Va. So then, in which circumstances does Vno has a practical application? Thanks Last edited by Skymaster15L; 3rd Jan 2013 at 17:23.
 13th Jan 2013, 16:32 #223 (permalink) Join Date: Nov 2009 Location: PK Posts: 171 hi need some help in the following two questions: Q.1. If you correctly tuned in a VOR situated to your east, your RMI should read ___ and your OBS would read ___ a) 000; 000 with needle central and TO indicated b) 090; 090 with needle central and FROM indicated c) 000; 000 with needle central and FROM indicated d) 090; 090 with needle central and TO indicated Just cant visualize this one. Q.2. The accuracy of a DME: a) is approximately ±0.5nm b) decreases with increase of range c) increases with increase of altitude d) is approximately ±2 nm Which accuracy is this? Slant range accuracy increases with increase in range. Thanks
13th Jan 2013, 16:46   #224 (permalink)

Join Date: May 2008
Location: UK
Posts: 1,339
Quote:
 a) 000; 000 with needle central and TO indicated b) 090; 090 with needle central and FROM indicated c) 000; 000 with needle central and FROM indicated d) 090; 090 with needle central and TO indicated Just cant visualize this one. Q.2. The accuracy of a DME: a) is approximately ±0.5nm b) decreases with increase of range c) increases with increase of altitude d) is approximately ±2 nm
1) you are tracking away from the VOR, therefore have 000 at the top, with the needle centered and the From flag. It would be incorrect if it were tracking 000, with 180 on the VOR and a FROM flag, as you would be going to the VOR and indications would be in reverse sense.

2) the error decreases with range. If you are over the station at 6000' (1nm) the DME will read 1nm, even though you are at the station. At 50 miles, at 6000', the error will be far less.

13th Jan 2013, 17:00   #225 (permalink)

Join Date: Nov 2009
Location: PK
Posts: 171
Quote:
 1) you are tracking away from the VOR, therefore have 000 at the top, with the needle centered and the From flag. It would be incorrect if it were tracking 000, with 180 on the VOR and a FROM flag, as you would be going to the VOR and indications would be in reverse sense.
but in this case the VOR will be south of you, whereas the question says its situated to your east.

Quote:
 2) the error decreases with range. If you are over the station at 6000' (1nm) the DME will read 1nm, even though you are at the station. At 50 miles, at 6000', the error will be far less.
Yes thats why posted the question. It says accuracy decreases with increase in range.

13th Jan 2013, 17:51   #227 (permalink)

Join Date: Mar 2012
Location: Central London
Age: 34
Posts: 321
Quote:
 a) 000; 000 with needle central and TO indicated b) 090; 090 with needle central and FROM indicated c) 000; 000 with needle central and FROM indicated d) 090; 090 with needle central and TO indicated Just cant visualize this one. Q.2. The accuracy of a DME: a) is approximately ±0.5nm b) decreases with increase of range c) increases with increase of altitude d) is approximately ±2 nm
Also interested in these questions.

I'm struggling to understand the first I'm afraid. Surely if the VOR is East of your position you will be on the 270 radial and would need a 090/270 OBS selection to get "to" or "from", respectively. Why would you ever get a reading of 000? Is this talking about a relative bearing?

What does 'correctly tuned' mean. Are you tracking inbound or outbound to the beacon?

Second question, if we know the required accuracy of a DME is 1/4nm + 1.25%, we know A and D are wrong.

C is wrong (accuracy decreases with increase in altitude as the vertical 'slant' component increases), so we are left with B as the least worst option. It's true to say slant accuracy increases with range but then DME is line of sight so eventually accuracy will decrease with an increase in range, as you pass beyond line of sight of the transmitter.

Last edited by taxistaxing; 13th Jan 2013 at 17:51.

14th Jan 2013, 05:45   #228 (permalink)

Join Date: Nov 2009
Location: PK
Posts: 171
Quote:
 Surely if the VOR is East of your position you will be on the 270 radial and would need a 090/270 OBS selection to get "to" or "from", respectively. Why would you ever get a reading of 000?
thats precisely why i posted the question

Quote:
 It's true to say slant accuracy increases with range but then DME is line of sight so eventually accuracy will decrease with an increase in range, as you pass beyond line of sight of the transmitter.
i was also thinking on these terms but not quite sure if this is really the reason.

 14th Jan 2013, 06:37 #229 (permalink) Join Date: Jan 2011 Location: mumbai Age: 29 Posts: 233 Is it possible that the question Q1. is incorrect?
 14th Jan 2013, 06:41 #230 (permalink) Join Date: Nov 2009 Location: PK Posts: 171 i think it is! how are your ground classes going
 14th Jan 2013, 09:47 #231 (permalink) Join Date: Dec 2006 Location: Hamburg Posts: 420 In my opinion the correct answer to the first question would be d). An RMI has no TO/FROM indication, so if the station is to your east, the needle will indicate east. As for the TO/FROM indication, it should indicate TO with 090 selected on the OBS.
 14th Jan 2013, 10:18 #232 (permalink) Join Date: Nov 2009 Location: PK Posts: 171 thats right, i think the question is wrongly marked thanks everyone for your feedback Last edited by Haroon; 14th Jan 2013 at 10:20.
 15th Jan 2013, 04:46 #233 (permalink) Join Date: Jan 2011 Location: mumbai Age: 29 Posts: 233 going good by God's grace
 19th Jan 2013, 15:47 #234 (permalink) Join Date: Nov 2009 Location: PK Posts: 171 Any idea about this one? What is the PRF given 50 micro second pulse width and a range of 30 nm: 1620 pps 810 pps 3240 pps 3086 pps What I know is: Max Theoretical Range = c / 2 x PRF 30 = c/2prf prf = 2700 Am i missing something, like something to do with 50 micro second pulse width or there is something else to it? thanks Last edited by Haroon; 19th Jan 2013 at 15:50.
 19th Jan 2013, 16:21 #235 (permalink) Join Date: Feb 2002 Location: Sunny Solihull Age: 60 Posts: 191 Long time since I did this but I THINK its 81000/50 = 1620 but can't remember why!
 19th Jan 2013, 16:44 #236 (permalink) Join Date: Mar 2012 Location: Central London Age: 34 Posts: 321 That's a strange one. Using 162000 nm/sec as SOL I make D the closest. A seems to equal 50 nm not 30.
 19th Jan 2013, 16:46 #237 (permalink) Join Date: Nov 2009 Location: PK Posts: 171 i think there's a typo in the question. It must be 50 nm
 20th Jan 2013, 04:16 #238 (permalink) Join Date: Dec 2011 Location: N/A Age: 27 Posts: 33 This was great help thanks a lot guys!
 20th Jan 2013, 06:54 #239 (permalink) Join Date: Nov 2000 Location: Littlehampton, Prestwick & Calgary Age: 65 Posts: 3,394 There are 96 articles and 18 Annexes, of which only about 6 are questioned on. Facilitation? You are not expected to know the fine details of contents of the articles, but definitions (sovereignty, etc) would be worth swotting up on. Also customs requirements and the 5 (out of the 9) freeedoms. Phil
 20th Jan 2013, 09:35 #240 (permalink) Join Date: May 2001 Posts: 10,858 In real life its Facilitation and Dangerous goods your most likely to come across.

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