Power Reduction & Descent in the Pattern

[ifconfig]

One strange thing I've noticed, you talk to a Kiwi, an Aussie, or a Brit instructor and chances are they'll have you reduce power either on base or as you're turning base along with starting the descent.

Of course, we are taught here to start descent abeam the numbers on downwind. Apart from wanting to keep the aircraft high in case of engine failure, what are the pros and cons of either practice?

 

[Fearless Tower]

Do they tend to fly big wide patterns?

I don't buy the engine failure argument. If you are in the proper position on the downwind, you could experience a complete loss of power abeam the numbers and you should still be able to make the runway.

 

[timwinters]

I'm typically putting along at about 100 to 110 kts on downwind and reduce power to idle abeam the numbers; put in a notch of flaps once the speed is in the white arc (87kts for my plane); and trim for approach speed (70kts for my plane).

The plane won't descend while doing this, but rather just slow down while remaining in level flight.

The descent usually begins about the time I'm turning base and add a second notch of flaps.

I fly a pattern that keeps me within glide distance of the runway.

But, as to your question as to why the diff 'twixt here and abroad...I have no idea.

Pros/Cons? I would think chopping the power abeam the numbers allows one to execute the tasks in a more systematic and less hurried manner. All the configuration and trimming is done on downwind which leave the base and final legs for concentrating on nothing but landing.

 

[ifconfig]

Do they tend to fly big wide patterns?

I don't buy the engine failure argument. If you are in the proper position on the downwind, you could experience a complete loss of power abeam the numbers and you should still be able to make the runway.

As far as I know from reading their instructional material, they teach to position the aircraft about a half-mile from the runway, using the usual marks on the strut for high-wing a/c and the tip of the wing on low-wing as well as using the 45° mark for base turns.

I agree with your engine failure premise. Perhaps it's to ensure the student isn't in danger of being low and/or slow by the time they're turning final? I have no idea.

 

[txflyer]

The trick I was taught if you lose power abeam the numbers or pretty much anywhere on the downwind is, you turn immediately towards the runway and head for it. Don't wait or try to fly a pattern.

Most fields are long enough you can land half way or more down the strip in a Cessna and you'll be just fine.

 

[poadeleted20]

Our 1000 AGL "standard" TPA is higher than most, and if you don't start down abeam the touchdown point, you won't make it down without flying a bigger pattern or using either idle power or a lot of slipping. Most other countries tend to fly lower patterns -- 600-800 AGL, where you have to wait longer to start down.

 

[Fearless Tower]

Our 1000 AGL "standard" TPA is higher than most, and if you don't start down abeam the touchdown point, you won't make it down without flying a bigger pattern or using either idle power or a lot of slipping. Most other countries tend to fly lower patterns -- 600-800 AGL, where you have to wait longer to start down.

That makes sense.

 

[ifconfig]

That makes sense.

Yes, it does. Except that the countries I'm talking about also have a ‘standard’ TPA of 1000' AGL. For example, Australia's Flight Instructor Manual shows a climb to 1000' AGL and then …

*Turn onto base, reduce power, select flap, trim and
allow for drift
​

Strange. Not that it matters much, it was just something puzzling I noticed.

 

[poadeleted20]

Maybe they fly wider patterns. Try it yourself and see what happens.

 

[Shepherd]

Do they tend to fly big wide patterns?

I don't buy the engine failure argument. If you are in the proper position on the downwind, you could experience a complete loss of power abeam the numbers and you should still be able to make the runway.

Not always. Your descent should be based on terrain, and nothing else. I fly into a couple of different airports where you can't even see the runway until you are on the last 1/2 mile of the base\start of your final. If you start down on base, your turn to final is into the side of a hill.
It costs you nothing to keep your altitude as long as possible, then scrub it off on final.

 

[Fearless Tower]

Not always. Your descent should be based on terrain, and nothing else. I fly into a couple of different airports where you can't even see the runway until you are on the last 1/2 mile of the base\start of your final. If you start down on base, your turn to final is into the side of a hill.
It costs you nothing to keep your altitude as long as possible, then scrub it off on final.

The OP was referring to generalities, not specific fields.

I understood the question to refer to standard patterns.

 

[fiveoboy01]

Do they tend to fly big wide patterns?

I don't buy the engine failure argument. If you are in the proper position on the downwind, you could experience a complete loss of power abeam the numbers and you should still be able to make the runway.

More than once my CFI pulled the throttle closed abeam the numbers and I never had any issue making the runway. There were even times where I did not immediately turn towards it, otherwise I would have been much too high over the fence.

 

[ifconfig]

Here's an interesting tidbit I just unearthed: back in ye olden tymes, the FAA's 'Flight Training Handbook' (AC 61-21A now superseded by FAA-H-8083-9A) had the following blurb about the base leg:

"The base leg is that portion of the airport traffic pattern along which the airplane proceeds from the downwind leg to the final approach leg and begins the descent to a landing."

So it seems that for a while at least, American CFIs were also teaching this particular technique.

Here's one CFI writing about why the technique of reducing power abeam the numbers came about in a book from the early 90s:

Back when light, fabric, two-seat taildraggers dominated the general aviation skies, airplanes were slower and glided better than today's trainers. You could fly a tighter pattern and initiate your descent earlier with no problem. If you tried to hold your pattern altitude until your base leg, you would be up there all day and get a lovely view of the airport as the runway passed way beneath you.

Airplanes have changed. Even our light trainers are faster, heavier, are all metal, and descend more quickly than earlier aircraft. The lengthened pattern which results from holding your altitude longer gives you a little more time to plan, gives you a steeper descent which improves your visibility, and makes extending your downwind a snap because you don't have to climb back up. So for all of the above reasons you develop better situational awareness.

Thoughts?

 

[LDJones]

Do whichever works for you and the airplane you fly. Like so many things in life, there's no definitively "right" or "wrong" answer. Just fly the airplane.

 

[flyingron]

If you're flying a 172 or smaller, it mostly doesn't matter. You can throw the plane where you want it. If you're flying something more powerful or slicker, you'll need to plan earlier. There's no way you're going to make a sane landing if you don't reduce power way prior to Base.

We were taught that rolling out on the downwind to base leg was the "key position" which means you decide if your prior planing is going to work out (are you too fast, too high). This is where you make your adjustment for the rest of the approach.

Having flown a bit (including doing the equivalent of a BFR) down in Australia, there's not an appreciable difference in pattern procedures ONCE YOU'RE IN THEM (and the fact that the radio calls take a slightly different format). The pattern entries are a bit different (and in my opinion saner) than the US version.

 

[ifconfig]

Do whichever works for you and the airplane you fly. Like so many things in life, there's no definitively "right" or "wrong" answer. Just fly the airplane.

Indeed, but speculative discussion is at least half the fun, no?

 

[ifconfig]

The pattern entries are a bit different (and in my opinion saner) than the US version.

Are you talking about descending on the so-called "dead side"?

 

[flyingron]

Are you talking about descending on the so-called "dead side"?

Not descending, but entering on the midfield crosswind is standard.

 

[drotto]

If your are talking what I am being instructed, power is generally reduced to 1500 rpm about the numbers on downwind on a typical approach, at which point the first notched of flaps is applied. After that do what is needed via pitch and throttle to maintain an appropriate approach speed and glide angle for the various legs. Usually (in trainers) power is put to idol "at the fence", but in my recent pattern work reducing to idol was needed right after tuning final in order to maintain the right speed and glide path (it was a cold dry day). So just about everything in the book should be viewed as adjust as needed.

 

[ifconfig]

I think it's hilarious that the FAA recommends through its manuals that the descent be started on the base leg and almost universally, pilots and their instructors have chosen to ignore it!

As it turns out, it's still on the books; in the current Airplane Flying Handbook, H-8083-3A, Chapter 8, page 8-2 one reads:

After turning onto the base leg, the pilot should start the descent with reduced power and airspeed of approximately 1.4 VSO. (VSO—the stalling speed with power off, landing gears and flaps down.)

I have a feeling that some Examiner will probably fail you if you do what the Handbook says until you prove it to him or her that it's in there. How funny!

 

[fiveoboy01]

And in Chapter 7 of the same book, it says that power should be reduced and a descent begun abeam the numbers on downwind.

 

[ifconfig]

And in Chapter 7 of the same book, it says that power should be reduced and a descent begun abeam the numbers on downwind.

HAHAH! Seriously? Of course it does.
I wonder if the writer had Obstructive Sleep Apnea?

 

[txflyer]

The prettiest greaser I made today was a wheelie with no flaps.

Imagine that.

Perfect flight conditions today. 65 degrees, no wind, visibility to Venus. Beautiful day.

 

[ifconfig]

The prettiest greaser I made today was a wheelie with no flaps.

Imagine that.

Perfect flight conditions today. 65 degrees, no wind, visibility to Venus. Beautiful day.

I envy you, pal.

 

[Xscaliber]

When home in the UK and flying into my home field, the ATC really make you do a long pattern (circuit in UK) when on final unless it's really bright clear day I often can't see the runway, it isn't unusual to be dragging it in on a 4 or 5 mile final !

It usually takes me a few laps around the pattern when back in Florida to get used to flying compact patterns again.

 

[dtuuri]

One strange thing I've noticed, you talk to a Kiwi, an Aussie, or a Brit instructor and chances are they'll have you reduce power either on base or as you're turning base along with starting the descent.

Of course, we are taught here to start descent abeam the numbers on downwind. Apart from wanting to keep the aircraft high in case of engine failure, what are the pros and cons of either practice?

You start your descent when you're on a normal glide path, at the proper speed, and not before. If you're too close to the runway on downwind, you'll need to start down then. If you're making bomber patterns, wait until base leg or final. It's not a nationality issue.

dtuuri

 

[Hank S]

When home in the UK and flying into my home field, the ATC really make you do a long pattern (circuit in UK) when on final unless it's really bright clear day I often can't see the runway, it isn't unusual to be dragging it in on a 4 or 5 mile final !

It usually takes me a few laps around the pattern when back in Florida to get used to flying compact patterns again.

Happens here, too. I've been turned downwind while still 8nm out . . . But I prefer downwind about 1/2nm away, about a third of the way in from the wingtip. Approach flaps on downwind to hold 90 mph, drop gear at the numbers and begin descent. At that point, pitch for speed, power for altitude, usually roll wings level on final at 85 mph with VASI/PAPI lights red & white when available.

It takes practice and more practice at multiple fields to do this. It's tempting at home to use ground reference points to fly the pattern, but that will hamper your ability to be consistent. Look over your shoulder and wait for 45 degrees.

In the Skyhawk, I used Flaps 10 on downwind; Flaps 20 on base; flaps, throttle and slip on final as required to land at the intended point of landing. Watch that spot on final--if it moves down the windshield you are high/fast and must correct or land long; if it moves up, you are slow/short and will touch/impact before your desired spot.

Once landing is assured and you know you can glide to the runway, throttle to idle and set her down. This point will obviously vary depending on obstacles and wind speed & direction.

Good luck, and practice often!