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CP Magazine's article by Mike Ray- a correction

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A reader on the iFLY support forum by the name of Sergey raised a question about Mike Ray's article "Transitions" featured in the latest issue of Computer Pilot Magazine which can be downloaded free.I emailed Mike about a possible error in the article. He kindly responded and I'm posting his comments here along with my emails to him:#1:Dear Mike,In the latest CP magazine on page73, you make a comment that the speed bug on the 737 is exactly 10kts wide. There is a discussion about this on the iFLY support web site in the ‘Pilots Lounge’ section and the consensus is that the bug is NOT 10 kts wide, but possibly only 5kts wide. Other panels also confirm this and I’ve even measured it on the screen. Also, when set resting on a speed mark, the top portion does not touch the next upper speed mark which is +10kts. We would appreciate your comments in the thread if possible. I’m including the link to the topic. http://ifly.flight1.net/forums/forum_posts.asp?TID=5954&title=mike-ray-transitions Hi James, WOW!!! You guys really are paying attention! I assume that you are on the iFly forum. This niggling detail is a throw-back to my days on the “real” Boeing 747-400. Whether it was by design, or by accident, the airspeed bug on the “UAL” PFD was “just about” 10 knots in width and the pointer was “just about” 5 knots from the bottom of the speed selector. This is just a simple gouge to make a quick estimate of the speed to select. Let me go up and crank up the PMDG 747-400 and the PMDG 737 NGX and the iFly 737 NG and see what their speed bugs look like. I’ll try to remember to get back to you. Mike Captain Michael J. Ray, PresidentUniversity of Temecula Press, incwww.utem.com#2From: Mike Ray [mailto:mikeray@utem.com]Sent: Wednesday, November 09, 2011 8:15 PMTo: 'James Dowgialo'Subject: RE: Speed bug size Hi James,OK … I can absolutely confirm that the width of the speed bug is … are you ready …5 Kts. The consensus is RIGHT!However, since I get to write the articles, I get to make mistakes that no one is supposed to notice.Good on all you that caught me. Mea culpa!Here’s the deal on using the width of the speed bug; since it is common practice when flying the line, that you set your speeds +5 or 10 Kts to account for wind gusts or turbulence or stupidity on the part of the crew. The width of the bug makes a nice reference. That’s all … it keeps you from having to do some basic math. Let’s see … 143 plus 5 equals … ? By the way … go to this website: www.halldale.comThen select the “MAGAZINES” from the toolbar.Then select the CAT (Civil Airline Training),Select Digital issue: CAT 5/2011Go to page 16.In that article you will hear them mentioning that there will be a major airline pilot shortage … and gives details.Nice read … and I’ll just bet that someone reading the CP magazine and sharing on the iFly forum will be one of those pilots. Happy Simming,Mike #3:Thanks Mike for the confirmation. I have all of your previous articles printed and in a binder next to my computer. I’ve learned a great deal from them as well as others whom have contributed their knowledge. I’ll keep this article too, although there will be an asterisk on page 73 next to the ‘bug’ size reference. I cannot take credit for this discovery though, that goes to the original poster who goes by the name Sergey. Yes, I dreamed of becoming a pilot in my youth, but at 67 years young next month, that is not now possible. But thanks to the great developers of in-depth aircraft, I can live a portion of that dream. Keep up providing the great information you have in helping us to become better pilots. Jim #4: Hi (again) James, I can’t seem to get on the iFly forum … So I am asking you if you could post my response regarding the 5 Knot bug thing for me. Thanks,MikeHi James … it is early morning (OMIGOSH … 4 AM) and I can’t sleep because this speed bug thing has me “bugged”. I can absolutely confirm that the speed bug is “5 Knots” wide. I said in the CP article that it was 10 Knots wide … I was wrong.So, just to make certain that we are both talking about the same thing, if you place the bottom of the bug on a speed value, the pointer end would rest on a value 2 ½ Knots “above” that speed.That speed then becomes the selected speed for the auto-flight system (or if flying manually, the Flight Director). These are nice little additional speed touches to avoid over-speeding during the extension of the flaps. The selection of the airspeed during the actual approach is somewhat more complicated.Here are the guidelines for speed selection during an approach … and these are specifically from my experience at United Airlines.We start with the approach Reference speed or “Vref” as the basic raw speed for the approach … and in the sim, you get that from the CDU when you select the “flaps” setting you intend to use for landing. I suggest that simmers write that down, because I can’t seem to remember it when I need it. The actual TARGET speed for landing is the Vref corrected for the actual wind component at the runway. And a short wind component discussion might be in order. The wind has two specific attributes that we are concerned with … and these are reported in the ATIS weather or by the controlling agency (usually the Tower or ATC): GUST and STEADY STATE. They say it like this, “ The wind is XX Knots from XXX gusting to XXX Knots. So we know 3 things about the wind. The direction it is coming FROM, the steady state component and the gust component.Here is the “rule”. Set your REF bug at REF (from the flaps driven CDU value) + ½ the STEADY WIND “component + the FULL GUST value.The maximum allowed wind correction should not exceed 20 Knots. The key feature here is the “component”. For example, If you are landing on Runway 9 … That is, the airplanes “track” over the ground when it is aligned with the runway will be approximately 090 degrees magnetic. The reported wind is probably NOT actually coming from exactly 090 degrees even though the operational runway is usually “into the wind”. So just what part of the wind is the “component”? This is a geometry problem … and there are wind component charts in the handbook that cover such things, but let’s say for our example that the wind is from 120 degrees at 10 knots gusting to 20. How much additional airspeed should we add to our Vref to be in compliance with the SOPs? We don’t need to add the whole 5 (½ of 10 Knots) + 10 (20 – 10) = 15 Knots. We only need to correct for that component or part of the wind that is opposite the track of the airplane. So you take the 15 Knots and correct it using a simple “wind triangle”. Roughly, we come up with a headwind component correction of about 13 Knots. I can teach you some simple techniques to address this issue with using a calculator … usually a “WAG” (or “estimate”) works just great. If in doubt … add 20 Knots. That will fir all the cases. Anyhow, since you guys are into the exact details of the problem, here is a nice “wind Triangle” computer you can use.http://www.luizmonteiro.com/Wind.aspx#WT I am sitting here thinking about this and wondering about this. Would be too complicated and not interesting to attack this issue in greater detail in a whole article in the CP magazine? Let me know what your thoughts are on that … I can probably twist the arm of the editor.It is obvious that I will have to correct my “error” from the last issue.Looking forward to your response. MikeI hope all enjoy Mike's correction. Jim D.

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Thanks for posting this information.Formula's were mentioned so here's a reference to them:http://en.wikipedia.org/wiki/HeadwindIt helps just to know the sin and cosine of 30 degrees and 60 degrees factors to guesstimate your headwind and crosswind components. Another factor is the faster your airspeed the less of a factor your crosswind headwind/tailwind component becomes.Remember that regarding indicated airspeed that is what concerns you about possibility of stalling. The stall speed varies upward if you are conducting a cross controlled slip to landing (opposite rudder/aileron) and without added thrust your descent rate also increases. A/P approaches to a LOC/ILS or VOR will normally crab (heading adjustment to compensate) for horizontal wind drift and only get uncoordinated controls esswentially applying a slip to straighten the nose in the flare before touchdown.Finally, any touchdown horizontal drift on the landing gear must be within the mechanical limits of the gear. Some aircraft have swiveling main gear structures to accommodate relieving this stress.OK. A bit off topic but someone mentioned 'formulas'.There are calculators to determine this as well as charts and GA pilots who don't like hand calculators use the old faithful E6-B essentially circular slide rule to determine wind components.For those who like V speed definitions:http://en.wikipedia.org/wiki/V_speeds#VREF

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