Pattern Width on Downwind

[Jaybird180]

One persons wide pattern is another persons normal pattern. When your down low and in a pattern a 1,000 foot difference in pattern width looks like a lot.

When I was taught landings, my instructor disuaded me from trying to find a reference point on the airplane to judge distance from the runway on downwind. His reasoning was that I would fly different airplanes and that I should learn to judge by sight alone. I think his guidance may have been misguided (or misunderstood by me).

As a result, refusing to commit the 'sin' of 747 size patterns, my pattern is often too close and lately become inconsistent.

I intend to do some pattern work soon, specifically to find a sweet spot and fix the issue. Can anyone make suggestions that I can use as a starting point (ie midway on wing strut, arm width of light beyond wingtip, etc)?

 

[Jim Logajan]

Can anyone make suggestions that I can use as a starting point (ie midway on wing strut, arm width of light beyond wingtip, etc)?

My humble suggestion and the one I have been using:

Use the length of the runway as your distance guide or ground ruler. You should know its length since that is required by 91.103(b).

Then try to mentally rotate the runway 90 degrees (trickier than it sounds) and estimate what fraction or number of runway lengths out you need to fly. Coincidently, most of the runways I use are around 3000 ft, or about 1/2 nm - just about the generally recommended distance for small planes.

In fact most runways I use are between 3000 and 6000 feet, so simply flying one runway length away on downwind should generally get you in the 1/2 to 1 mile range I've seen recommended.

 

[Jim Logajan]

No problem. Just take the churches and the pond with you on cross-countries.

Weight and balance might be an issue. :wink2:

Although I've suggested using the helpful reference ruler every airfield has laid on the ground for you (the runway itself) to measure your distance from the runway, it can be tricky trying to take advantage of it due to perspective. Below is an image created using Google Earth from about pattern height of my home airfield. The runway length is ~3100 ft. Both red lines are ~3100 ft long, and the one perpendicular to the runway shows how far away one would have to be ~1/2 nm from it. The lines don't look equal length thanks to the difference caused by the angled perspective, but they really are equal ground lengths.

When I tried using this technique a few weeks ago, I got close but overestimated the distance, as you can see by this recorded CloudAhoy track (click on Debrief and allow some time for Google Earth app to load):
http://www.cloudahoy.com/cgi-bin/fltShare.cgi?share=19Xrl3Dq9gIy1G2Ox383Ef

 

[Jim Logajan]

Probably not going to work very well on an emergency off airport landing.

True - as Jim Meade pointed out, anyone who has had glider training will use sight angles. Gliders trying to fly cross-country have to learn how to land out at sites of uncertain elevation. And often away from objects of known size.

A good book the OP should buy and study is "Glider Basics" by Thomas Knauff. The "Landings" chapter (subtitled "The TLAR, or That Looks About Right technique") should provide some useful insights.

 

[Jim Logajan]

That is 2-4 times as far as you should be on a 1000'AGL downwind IMO. 45* to the runway is a 12/12 pitch or 1000' over for 1000' up. if you have a strong cross wind pushing to at the runway step it out approximately the percentage of 1000' that matches the percentage of the crosswind component of your airspeed. IE 15kt X/W component in a 100kt airplane move out another 150'.

The 0.5 to 1 mile suggested distance comes right out of chapter 7 of the FAA's Airplane Flying Handbook. But I would agree that anything much beyond 2500 to 3000 ft seems needlessly far for the average small plane.

But when I've flown as close as about 1500 ft, the base leg (for me at least) becomes mostly a half circle. I don't get a good chance to fly the base long enough to take another good look to see anyone doing a straight in approach before I turn final.