dtuuri
Final Approach
Modern-day holding pattern entries assume pilots apply wind correction to the outbound headings. In fact, the protected airspace assumes they err by half the proper amount. What "book" do you go by?
dtuuri
VOR-A Question
- Thread starter CRLBernstein
- Start date
dtuuri
midlifeflyer
Touchdown! Greaser!
More math is required to choose the boundary between an AIM parallel and a teardrop.
I generally use the "draw the hold" method of selecting entries and "hmm... looks like [type of entry] works" is all the math I do.
Note that I never said in any post that I would choose the teardrop in Ron's scenario. I wouldn't. It doesn't make operational sense to me. I'd use parallel.
But it apparently makes sense to someone else. The only thing I'm wondering at this point is whether, if someone chose to turn 120° rather than 90° (give or take), it would put them outside of protected airspace and under what conditions.
John Collins
En-Route
John Collins
En-Route
I can't see how it would, the extra 10 seconds of turn is towards the center of the holding area, rather than parallel to it.
dtuuri
Final Approach
But there is no 'choice' unless your heading at the fix is within + or - 5° of that boundary. Beyond that, if someone wants to force a teardrop entry where a parallel track is the underlying assumption, I'd say the onus is on them to prove it remains within protected airspace, which would be impossible without knowing the exact template used out of 31. Of course the 'odds' of staying within protected airspace would be in their favor, given that the actual wind is probably below the assumed one, but simply flying the AIM-intended entry is correct by default--without any proof.
Technically, even if you have drafting tools for eyes, that method uses 'intended' ground track. The FAA's method assumes proper wind correction and is based on the arrival heading. Partial panel, though, with the whisky compass, I'd use that method too.
Again, it depends on the actual wind and the template used. An examiner would surely wonder too, so the burden of proof should lie with the applicant if they choose to ignore the FAA's underlying assumptions and published procedures.
dtuuri
dtuuri
Final Approach
"Development of Holding Pattern Criteria and Procedures", Order 7130.8. See Chapter 4, Par 21.b for "Holding Side" entries; and Par 27.b.(2) for "Random" (now called "Parallel") entries.
See Figure 2 in the above document. Mark Kolber would be interested in that one, re: his post, too.
Note: Order 7130.8 is not available on the FAA's website. Wally Roberts posted most of the pages on the Red Board a few years ago, if you want to search there. Page four (4) is missing from that document, so I acquired it myself from the FAA and you can access it here: http://www.AvClicks.com/files/Order_7130_8_Page_4.pdf .
For those not able to search the Red Board, I'll publish Wally Roberts' version of the Order, complete with his annotations about the missing page 4, Here and trust that he has no issues with my doing that. After all, it is a government document.dtuuri
roncachamp
Final Approach
Would you use the procedure that your original CFI described if the turn from the 330 radial to the 299 radial was a turn to an airway segment instead of an approach segment?
I wouldn't go all the way to the VOR in this case, I'd begin my turn from V141 about four miles northwest of CON.
roncachamp
Final Approach
I've seen airway routings that involved 180° course changes over VORs.
W. Stewart
Pre-takeoff checklist
As I think I clarified further down in the thread, our home-base approach with similar geometry is an NDB approach. Barring GPS (which, admittedly, is becoming more ubiquitous, but he never had it all those years, and I did not have it until recently), how does one KNOW when he is four miles from said NDB?
I think that he came up with his method as a sure-fire way of knowing where he was and getting properly aligned with the outbound course in as short of distance as possible (therefore less likely to exceed the 10 nm radius). Brisk needle swing upon passing the beacon gives reassurance that one is indeed over the beacon. Also, getting established on the outbound course as early as possible can help one judge the wind effect, which will help when back inbound. To turn right and therefore try to intercept a bearing off an NDB at some distance from the beacon (and once again intercepting that course at a fairly obtuse angle) is difficult--in a plane like a King Air, one can be fairly far from the NDB at that intercept point.
Wells
(still hoping that Wally comes on and can cite the TERPS design criteria and/or a regulation for first turn towards the outbound course)
gismo
Touchdown! Greaser!
I thought that Terps limited airway turns to a maximum of 120°. But I wouldn't claim that a greater turn angle isn't possible somewhere. Can you post such a turn?
chucky
Line Up and Wait
He said routing, which is given by ATC (so, controlled by JO 7110.65, not Terps). Say your initial fix requires flying in roughly the opposite direction from the direction you'll fly on the airway. I've never gotten a full 180 degrees, but when I flew out of New Haven, any north route would involve a pretty sharp turn from either Bridgeport or Madison, depending on the airway. Of course, you didn't usually end up overflying the VOR - they'd just vector you on to the airway. One of my first IFR flights, though, New York was non-radar, and I had to do a fairly large turn over Madison.
dtuuri
Final Approach
Not Wally, but the AIM spells it out:
"Pilots should begin the outbound turn immediately after passing the procedure turn fix."
That's from Paragraph 5-4-9a.3. Also see FIG 5-4-16.The room to play games with (not that 'games' are approved) varies from three to ten NM in the entry zone, according to Table 1A, Par 234, Volume I of TERPS. I have a direct link to TERPS in the 'Click School' at my website www.AvClicks.com .
dtuuri
Last edited:
gismo
Touchdown! Greaser!
And the very same AIM includes this statement a couple paragraphs earlier:
"However, the point at which the turn may be commenced and the type and rate of turn is left to the discretion of the pilot (limited by the charted remain within xx NM distance)."
In reality, if the "PT fix" (i.e. the fix you must cross before beginning the PT) is also the FAF and your altitude won't leave you too high, there's little reason to delay initiation of the PT. But for an on field "PT fix" or when you have excess altitude to lose, going outbound a couple minutes before turning off course can make life simpler on an approach. I've also found that when there's a significant crosswind, continuing beyond a VOR FAF a couple minutes makes it a lot easier to sort out the proper wind correction angle. Of course that isn't such a big deal if you have GPS.
roncachamp
Final Approach
What was your routing to ZEF NDB?
roncachamp
Final Approach
Sure; BRD V82 GEP V413 BRD.
dtuuri
Final Approach
A picture would probably help. I'll try this without, though.
My comments were to W. Stewart's CFII's idea of using the entry zone for homemade maneuvers to re-cross the fix a second time lined up on the outbound course--an extra ad-hoc procedure turn prior to the actual published procedure turn. I see nothing in your cite from the AIM that permits that, since "...the point at which the turn may be commenced...," obviously refers to the turn to the inbound course, not the turn to outbound which must be done immediately upon crossing the fix the first time.
I think you are discussing outbound timing, in which case the more time outbound, the less rushed the descent rate needs to be on the flip-flop. Usually, on-field VORs require greater altitude loss before returning to the PT fix (missed approach point=VOR) than approaches with the VOR as the FAF some distance from the field, so extending the outbound procedure turn makes life a lot easier. Was that your point?
dtuuri
Last edited:
gismo
Touchdown! Greaser!
My bad. I completely missed the fact that the immediate turn you talked about and the AIM paragraph you quoted was in reference to the turn to the outbound leg of the PT not the first turn of the reversal to inbound. The AIM text is clear on second reading.
Yes, albeit a bit off the original topic.
dtuuri
Final Approach
It's a good point to make anyway. Thanks for bringing it up. New instrument pilots might tend to make mechanical steps by rote then wonder why they're too high to land, rather than thinking ahead and planning for the altitude loss required.
dtuuri
W. Stewart
Pre-takeoff checklist
Thanks, Dave. That is exactly the sentence I found and referenced in a post above "AIM 5-4-8 (a) (2) 'Pilots should begin the outbound turn immediately after passing the procedure turn fix.' "
BUT. . . I was looking in a copy of the AIM from 1999 (the one I happened to grab when researching this thread). The 1999 book did not have the figure you referenced--I looked in my 2010 copy, and there it was. The figure certainly demonstrates a turn in the shortest direction back to the outbound course.
Speaking of which, wow. . .that section of the AIM has EXPLODED between the years 1999 and 2010. I wonder how often and to what degree (non-professional?) pilots spend looking through updated material each year? It is funny--I already spend way more reading time with my avocation (flying) than I do with my vocation (ophthalmology). That is what is so great about these webboards--they help keep one's head in the game (even if one only flies 70-100 hours a year like I do). I spend many more hours thinking about flying than I actually do flying.
Wells
W. Stewart
Pre-takeoff checklist
I checked my logbook to find out, as he and I have flown practice approaches into out home airport several times over the years. In this case, we had done an approach at KINT, then KMWK, and then flew home after a "miss" at KMWK. I think that, upon missing at KMWK we climbed and then flew home to KZEF, so the course between KMWK and the ZEF beacon would be roughly 235, requiring essentially a 180 degree turn for the outbound course or 062.
Wells
W. Stewart
Pre-takeoff checklist
I think we have about beat this to death now, but I appreciate your input. Again, he is my original CFI, and a friend, but he is not a CFI-I (I had to bring PIC to town for the instrument instruction). He has flown King Airs in and out of KZEF for 30 or 40 years, though, and in days where an ADF was all he had. I can see his method as a method to get properly aligned on the outbound segment, and to not exceed the 10nm. I will continue doing what I was doing prior to him suggesting the alternative. I am glad to finally have GPS, as it sure makes this much easier.
Thanks again.
Wells