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Author Topic: When do YOU descend from pattern altitude?  (Read 1137 times)

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Cabbage

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When do YOU descend from pattern altitude?
« on: February 15, 2017, 07:53:38 AM »
Food fight.  Just thought I'd start a thread out of curiosity and for discussion.

Found an earlier thread that kind of touched on it, but not exactly.  I'm not saying one way is right or wrong, just curious.

You are in the pattern on downwind at pattern altitude.  When do YOU start your descent?  Abeam the numbers?  When you start your base turn?  Someplace else?

Personally, I start my descent when I start my base turn.  I start my turn based on TLAR.  On downwind I'm usually at 105 KIAS, put the gear down abeam the numbers, once the gear is down I select full flaps, look over my shoulder and if it looks about right I start the turn and descent.

hotrod180

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Re: When do YOU descend from pattern altitude?
« Reply #1 on: February 15, 2017, 08:47:08 AM »
I like to be down to flap speed (100) by midfield downwind,
I usually pull on a notch there, retrim  (for about 75-80),
and actually start descending downwind abeam.
One of my pet peeves BTW is the huge patterns I see some people flying. To those people:
please keep it in close enough that others who fly a tight pattern can at least see you without binoculars.

N804RV

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Re: When do YOU descend from pattern altitude?
« Reply #2 on: February 15, 2017, 09:11:10 AM »
Typically Vfe on the downwind, reduce power abeam the numbers and add first notch of flaps and trim for approach speed.  Actual descent doesn't start until the aircraft is trimmed, usually somewhere between the abeam position and the turn to base.
Ken W.
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will moffitt

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Re: When do YOU descend from pattern altitude?
« Reply #3 on: February 15, 2017, 11:23:53 AM »
I guess it has been a dry spell so any thread will do.  No flaps, lots of drag.  Cut the power and it drops like a rock.  If I am in a layed back attitude I will pull the trim all the way back and cut the power at the numbers and glide in, I guess you could call it a glide as it is a very fast decent.  If I feel awake I go a little past the numbers and point it down hill for a very short pattern.  90 over the fence will very quickly be 60 and an easy turn off mid field.  No two the same.  I always listen for traffic a ways from the field and announce my every move.   Because my patterns are small I keep an extra eye for larger, normal, patterns.  I can keep about 1500 and do a normal size pattern if there is traffic. No use to be a headache and a safety hazard.  If there is daylight  available most of my flying is in the evening and there is almost no traffic, even at busy Anacortes.   It was built for fun, why be bored.

will

tosten

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Re: When do YOU descend from pattern altitude?
« Reply #4 on: February 15, 2017, 12:32:39 PM »
Depends.  On the plane, on the conditions.


In the Debonair, by myself, nobody ahead of me.  Drop the gear and chop the power abeam the numbers and wheel it around for a tight, short approach.

Paul

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Wombat

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Re: When do YOU descend from pattern altitude?
« Reply #5 on: February 15, 2017, 05:34:38 PM »
In my Mooney and what I teach my students in C150's:

  • Upwind to Crosswind turn is based on altitude:   700' AGL
  • Crosswind to Downwind turn is based on distance from the extended centerline of the runway.   1/4 to 1/2 mile.  Pick the same distance every time for a given model.  It should generally be near where you reach 1000' AGL as well, but that's an indicator, not the target.  Your altitude when you reach that point depends on performance and weight and how well you maintained Vy on your climb.
  • Midfield downwind: Configure aircraft (cowl flaps, gear) for landing and reduce power or add drag as necessary to achieve Vfe  by the approach end of the runway.
  • Abeam the Approach end of the runway: Add flaps and reduce power to maintain 500FPM descent at desired airspeed.  Maintain altitude until flap speed if starting too fast.
  • Base turn is based on being 45 degrees from approach end of the runway: Add flaps and turn base.   Adjust power to maintain 500FPM at desired airspeed.   This should be at about 700' AGL, but the altitude is an indicator rather than the measure.
  • Final turn is prior to reaching the extended centerline: Add flaps and turn final.   This should generally be at about 500' AGL.   If you are low, turn earlier and more gently.  If you are high, turn later and bank steeper. (never above 30 degrees angle of bank) Adjust power to maintain 500FPM descent at your desired airspeed.
  • If you are not on the glide slope (above or below) maintain airspeed and adjust power to return to the glide slope within 1/4 of the way to the runway.   As soon as the first PAPI/VASI just starts to change, return throttle to standard 'final approach' position.
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JugheadF15

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Re: When do YOU descend from pattern altitude?
« Reply #6 on: February 15, 2017, 11:14:55 PM »
Abeam the numbers at the latest. 

skylanemurf

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Re: When do YOU descend from pattern altitude?
« Reply #7 on: February 16, 2017, 07:28:41 AM »
My target is to start my descent abeam the numbers but that varies a little depending on traffic and what airplane I'm flying

Domenick

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Re: When do YOU descend from pattern altitude?
« Reply #8 on: February 16, 2017, 09:35:15 AM »
At Harvey's 2700' field with displaced thresholds in my Piper Warrior: Like hotrod180, I want to be less than 100kts about mid-downwind, so adjust power and trim to attain.
Abeam the numbers, reduce power and pull 10* of flaps. Trim for 80 kts.
Base turn at about 700' AGL. Pull to 25* of flaps. Trim for 70 kts.
Final turn at 400-500' AGL. Pull to 40* of flaps. Trim for 60-65 kts.
Cross the fence at 60 kts.

Will's suggestion of cut power, no flaps, trim all the way back sounds like fun. 90 kts over the fence at Harvey likely means either over the road at one end or into the drink at the other. So I'll try it at Skagit.
Domenick
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Snohomish, WA, Harvey Field, S43

will moffitt

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Re: When do YOU descend from pattern altitude?
« Reply #9 on: February 16, 2017, 05:40:40 PM »
I like most people did not realize how draggy biplanes are.    When you cut the power you really put on the brakes.  There is no such thing as floating down the runway.   It is a completely different airplane than the c150 I had for 25 years.  And a lot more fun.  I call it my mistress, and so does the wife as she sometimes says I spend more time with "her" than I do with "Her".

will

Cabbage

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Re: When do YOU descend from pattern altitude?
« Reply #10 on: February 17, 2017, 08:18:51 AM »
At Harvey's 2700' field with displaced thresholds in my Piper Warrior: Like hotrod180, I want to be less than 100kts about mid-downwind, so adjust power and trim to attain.
Abeam the numbers, reduce power and pull 10* of flaps. Trim for 80 kts.
Base turn at about 700' AGL. Pull to 25* of flaps. Trim for 70 kts.
Final turn at 400-500' AGL. Pull to 40* of flaps. Trim for 60-65 kts.
Cross the fence at 60 kts.

Will's suggestion of cut power, no flaps, trim all the way back sounds like fun. 90 kts over the fence at Harvey likely means either over the road at one end or into the drink at the other. So I'll try it at Skagit.

But at what point do you descend out of pattern altitude?  As soon as you get to 80?  While you are slowing to 80?  Same time you turn base?

Cabbage

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Re: When do YOU descend from pattern altitude?
« Reply #11 on: February 17, 2017, 08:21:24 AM »
I posted the same question on Mooneyspace.  It appears I am in the minority.  Almost everybody else starts their descent while still on downwind.  The only other person so far that waits until they turn base is a guy from England that is required by regulation to do that.

richardwg21

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Re: When do YOU descend from pattern altitude?
« Reply #12 on: February 17, 2017, 10:45:39 AM »
From the Airplane Flying Handbook, 7-4, "Pattern altitude is maintained until at least abeam the approach end of the landing runway. At this point, the pilot
should reduce power and begin a descent." https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/09_afh_ch7.pdf

Domenick

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Re: When do YOU descend from pattern altitude?
« Reply #13 on: February 18, 2017, 08:16:47 AM »
...
Abeam the numbers, reduce power and pull 10* of flaps. Trim for 80 kts.
...

But at what point do you descend out of pattern altitude?  As soon as you get to 80?  While you are slowing to 80?  Same time you turn base?

When power is reduced, and flaps let out, the plane slows and begins to descend. So I begin my descent abeam the numbers or how ever long after I start trimming to 80 kts.
Domenick
PA-28-161
Snohomish, WA, Harvey Field, S43

BruceAir

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Re: When do YOU descend from pattern altitude?
« Reply #14 on: February 21, 2017, 08:48:44 AM »
The guidance in the Airplane Flying Handbook is the general procedure that works well in most circumstances.

But you should use judgment. For example, the other day, I was at Toledo, WA (KTDO) with a customer. The TPA there is 800 AGL. Delaying the start of the descent until you're ready to turn base (or on base) makes sense. The same applies when using runway 13R/31L at KBFI, where the traffic pattern is also 800 AGL.

Wind, wake turbulence, and traffic are also factors. You may need to extend the downwind leg to follow traffic or to make a space for traffic waiting to depart. You might want to stay high if you're following a heavier aircraft.

And some airports have noise abatement procedures that require non-standard traffic patterns that keep you either closer or farther out than normal.

In other words, review the Chart Supplement (A/FD) and other sources to learn about the airport you plan to use, and be prepared to adjust your habits as necessary when circumstances require.
-Bruce
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