bio15
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How To Enter A Holding Pattern?

Mon May 29, 2006 3:17 pm

I have seen holding patterns in which the direction for entering the pattern is opposite to the one of the pattern itself. It's not clear to me how is the pattern supposed to be flown into. Here's a picture of a holding pattern illustrating my question:



If there's an aircraft holding initially, what is the risk of another plane flying into the pattern head on with the plane previously holding? My guess is that this doesn't happen, but instead the way of entering the pattern is to first deviate from the path shown in the chart, and merge with the "downwind" leg in the correct pattern direction (Not fly direct to the intersection). Is this right? Thanks in advance.

Alfredo
 
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Zkpilot
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RE: How To Enter A Holding Pattern?

Mon May 29, 2006 4:16 pm

There are 3 types of entry into a hold: Parallel Entry, Offset Entry, Direct Entry. Your example is a Parallel Entry.
Parallel entry occurs in the 110deg sector that is heading opposite to the inbound (like your example). The aircraft fly over the beacon, fly along the inbound leg but heading outbound then make a 180 deg turn (towards the outbound and then back onto the inbound).Photobucket - Video and Image Hosting

Offset entry occurs on the remaining 70deg sector heading opposite to the inbound...fly overhead the hold point, fly towards the outbound (less than 30deg from the inbound), then make a turn onto the inbound.Photobucket - Video and Image Hosting

Direct Entry:Take 360deg around the hold point inbound leg. 70deg sector on the holding side of the inbound (ie incl the outbound leg) and that is your direct entry all the way thru to the opposing 70deg angle opposite.
Photobucket - Video and Image Hosting


this page shows it best http://bathursted.ccnb.nb.ca/vatcan/...rchives/20030518/CurrentTopic.html

[Edited 2006-05-29 09:20:07]
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Zkpilot
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RE: How To Enter A Holding Pattern?

Mon May 29, 2006 4:22 pm

Quoting Bio15 (Thread starter):
If there's an aircraft holding initially, what is the risk of another plane flying into the pattern head on with the plane previously holding? My guess is that this doesn't happen, but instead the way of entering the pattern is to first deviate from the path shown in the chart, and merge with the "downwind" leg in the correct pattern direction (Not fly direct to the intersection). Is this right? Thanks in advance.

As for this, a/c don't hold in a pattern at the same altitude... they stack them ontop of each other... the pattern is still the same... you could have for example 5 aircraft all holding together but several thousand feet high.
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bio15
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RE: How To Enter A Holding Pattern?

Mon May 29, 2006 5:44 pm

Hi Zkpilot, thanks for the response, it's clear to me now.

----

Taking a closer look at the diagrams I find the pattern entry paths rather odd, specifically the chosen angle, 70°.


For the pattern described above:

* I picture an aircraft going for the parallel entry (#1 on the diagrams), but very close to the direct entry (#3 on the diagrams). That is, very close to the 70° line but still going for a paralell entry path. In this case the aircraft should make a very tight left turn not to go too far off course of the pattern.

* The other case is an aircraft going for a direct entry, but close to the 70° line limiting with the offset entry (#2 on the diagrams). Here it would be necessary to make a tight left turn and then immediately the right turn not to overshoot the pattern on the outbound leg.

I would think that having 90° sections is the more reasonable choice. Having 180° space perpendicular to the pattern for direct entries, and 90° for offset and paralell entries each. Yet, I am certain there is a pretty good explanation for the angle being chosen as 70°. Do you happen to know what is the reason?


Alfredo
 
ThirtyEcho
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RE: How To Enter A Holding Pattern?

Mon May 29, 2006 5:57 pm

Bear in mind that how you enter a hold is your business, as long as you remain within the hold's protected airspace according to ATC's instructions.

The nice diagrams, above, are really only suggestions based on long experience. Some of this is based on the pre-radar notion of timed approaches wherein you were cleared to hold and given a time to depart the holding fix toward the approach fix. Mix that in with a fixed-card ADF or a Four Course Range approach and you'll see why the old-timers had gray hair.
 
MrChips
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RE: How To Enter A Holding Pattern?

Tue May 30, 2006 3:57 am

Quoting Bio15 (Reply 3):

* I picture an aircraft going for the parallel entry (#1 on the diagrams), but very close to the direct entry (#3 on the diagrams). That is, very close to the 70° line but still going for a paralell entry path. In this case the aircraft should make a very tight left turn not to go too far off course of the pattern.

* The other case is an aircraft going for a direct entry, but close to the 70° line limiting with the offset entry (#2 on the diagrams). Here it would be necessary to make a tight left turn and then immediately the right turn not to overshoot the pattern on the outbound leg.

Incorrect - they're both parallel entries.

Why? Because this is a NON-STANDARD hold - all turns are to the left, instead of the right.

Quoting Bio15 (Reply 3):

I would think that having 90° sections is the more reasonable choice. Having 180° space perpendicular to the pattern for direct entries, and 90° for offset and paralell entries each. Yet, I am certain there is a pretty good explanation for the angle being chosen as 70°. Do you happen to know what is the reason?

There is a good reason - it allows you to stay within the protected airspace set aside for the hold. When flying a hold, you use a rate one turn (3 degrees per second), and this can give a rather large turn radius at higher speeds. Utilizing the offset angles prevents pilots from making these huge turns and getting lost in the hold in the process (believe me, it can happen easily).
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corey07850
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RE: How To Enter A Holding Pattern?

Tue May 30, 2006 4:58 am

I'd opt for a teardrop entry myself... Hit the fix, turn to a heading of 134 for a minute, standard rate left turn to intercept the 284 course inbound and you're set

Parallel entry is pointless since you are tracking the same radial off the missed approach to the holding fix. Once you hit the fix and fly outbound for your "entry" you are simply flying along the inbound course. This does nothing to help you enter the pattern.
 
bio15
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RE: How To Enter A Holding Pattern?

Tue May 30, 2006 6:40 am

Quoting MrChips (Reply 5):
Why? Because this is a NON-STANDARD hold - all turns are to the left, instead of the right.

Hi Mr. Chips

I was referring to a hold like the one described on the diagrams posted by zkpilot, which consists of right turns. For the BLAKO hold, imagine the two situations I described, but inverted for the right hand holding pattern.

In other words, entering a hold like BLAKO but heading 360° instead of 104°, according to the reccomendations, should be in parallel, which would force a tight right turn. From that angle it would probably be more convenient to perform a direct entry.


Alfredo
 
SlamClick
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RE: How To Enter A Holding Pattern?

Tue May 30, 2006 6:51 am

Quoting ThirtyEcho (Reply 4):
Bear in mind that how you enter a hold is your business, as long as you remain within the hold's protected airspace according to ATC's instructions.

Exactly right! In the bad old days there were examiners who would bust you on a checkride for doing - in their opinion - the wrong entry. I'd sure as hell protest that! Worse, they'd look for approaches with high-workload missed approach procedures.

Think of it as a practical matter instead. You have lots of room on the HOLDING side of the radial and lots of room on the OUTBOUND sector. So keep your maneuvering over there. Each one of those entries does that, meets that criteria. Try not to stray over to the NON-holding side and especially so at the FIX end of the pattern. Beyond that, ain't no big!
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