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Finding Other Planes

Visually scanning for traffic is an important skill, and it is often overlooked in training.

To find other planes in the sky get used to a simple search pattern called a scan.

The core of the scan is looking in small 10 degree segments within your view. Choose a small area of the sky and focus your eyes there. How small of an area? Imagine a 172 about a mile away. You need to focus within 3 or so wingspans of the plane. By focusing your eyes in such a small area , your brain can look to infinity and pick out planes at much farther distances than normal.

You can try this on the ground. Find a place where you have a decent view towards the horizon. Almost anywhere will work if you aren’t facing tall trees or buildings. Take a lot of time and focus your eyes into the distance in a very small area. It helps if you look towards airports or cities. If you do this long enough, when a plane comes by you will see it where you otherwise might never have picked it out of the background.

Expanding the Search

It doesn’t really help if you are only looking for traffic in one part of the sky. So we need to scan in a pattern.

There are two basic patterns to use and it is up to your preference to decide which one you like.

  • Start looking to your left and scan each 10 degree section for 3 seconds or so before moving on to the next until you have scanned all the way left to right.
  • Start scanning in the center of your vision and then work your way out to both sides until you have scanned the whole area.

The important thing is to be looking for traffic. This will already put you ahead of many pilots who are not scanning!

Blind Spots

Flying high-wing aircraft? How do you see other planes while turning? You can’t! This means that you MUST lift the wing before beginning a turn. So when you are about to turn left, bank to the right about 15 degrees and look to the left. Then begin your turn to the left.

Look at your cockpit structure. If pieces of the frame are blocking your vision then lean around them to look outside.

You should normally be scanning an area of about 60 degrees in front of you. Be aware, however, that a plane can approach at a very shallow angle right next to you. Be sure to look to the sides occasionally and make sure another aircraft isn’t getting too close.

Eye Fatigue

Looking for other traffic can be tiring. You can reduce fatigue by maintaining an outside scan more than an inside scan because switching between looking near and far is one of the more fatiguing things to do to your eyes.

It is recommended that you spend one quarter or less of your time looking inside the cockpit.

Once you find traffic you need to react appropriately to avoid a collision.

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Instrument Meteorological Conditions

Instrument meteorological conditions (IMC) exist when an aircraft is in weather conditions that are not within the VFR visibility and cloud clearance requirements.

This means that you are in IMC if:
• You are inside of a cloud
• The visibility is too low
• You are too close to a cloud

When you are in IMC you need to be flying an instrument flight plan. Flying VFR into IMC is very dangerous and there are a multitude of accidents that occur this way. Don’t be a statistic! Stay away from the clouds.

In fact, I recommend having personal minimums for visibility and cloud clearance that are even more restrictive than the rules.

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Visual Flight Rules

Visual Flight Rules, commonly called VFR, are a set of rules that apply to planes flying by visual reference. This is in opposition to IFR (Instrument Flight Rules), flown without visual references.

This set of rules allows a pilot to fly in most airspace without a flight plan, clearance, or ATC communication.

VFR flying requires constant vigilance for other traffic and reliance on oneself for navigation.

When you are flying VFR you must be in VMC.

Of course, while flying VFR you may choose to use air traffic control services to:

  • Get help in an emergency
  • Get directions
  • Get traffic advisories
  • Get clearance through airspace or to land

How do I know if I’m flying VFR?

Did you file and open an instrument flight plan? If not, then you are flying VFR. You must comply with all VFR regulations including visibility and cloud clearance minimums.

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Visual Meteorological Conditions

Visual Meteorological Conditions, or VMC, are a set of weather conditions that allow for flying VFR.

Generally, VMC means good weather, but it also technically means that you are far enough between the clouds to allow for safe VFR flying.

For example, when flying IFR you might be popping in and out of clouds every few minutes.

If ATC notifies you about traffic then you must try to find the other plane. However, this only applies if you are in visual conditions at that moment. If you happen to be inside of a cloud you just respond with “IMC”.

In addition, it is also possible that you are near clouds and you can’t see the other plane because he is in a cloud. I will always take a quick look but if there is a chance that I can’t see the other plane because there is a large cloud right where he should be, I will still say “IMC”.

I am letting the controller know that the conditions where I am flying are not sufficient for VFR, even though I may be outside of a cloud at that time.

How do you know if you are in VMC?

I’ve devised a set of easy rules to help you remember the cloud clearance and visibility requirements for VMC.

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Haze Layer

The air on our planet is full of particles of moisture. These are often visible as haze, usually in calm air or on humid days. Did you know that on many days, when the air is stable, you can get above the haze and the visibility goes way up?

Click on the picture below to view it full size. You can see the haze extending to the horizon and up to a clear “haze line”. Above this line the visibility is much higher. It will be easier to see other planes at this altitude.

Haze Layer – click to view full size

Calculating the top of the haze layer

The haze layer will generally be present in stable air where the temperature is above the dewpoint. At an altitude above the haze layer, the temperature will be below the dewpoint, so any moisture in the air will condense into droplets of mist of rain. Then gravity will pull these droplets down until they are back in the haze layer where they will turn back into water vapor (haze).

So the simplest way to find the top of the haze layer is to determine where the temperature and dewpoint will match.

The air is colder at altitude, but do you know how much colder? There is something called the adiabatic lapse rate, which is the rate at which the temperature drops as you climb.

It varies depending on the moisture of the air but as a rule of thumb just assume it is 2 degrees Celsius per 1000 feet of altitude. In dry air, it may be as high as 3 degrees Celsius.

So when you listen to the AWOS at sea level and it reports “temperature 12, dewpoint 6” then you can figure out the approximate top of the haze layer. That is a 6-degree difference, so we will need to climb 3000 feet.

This quick rule of thumb will let you make the haze layer calculation very quickly, just find the difference and divide it by 2 to get the altitude of the haze line.

for example:

Temperature: 10C, Dewpoint: 5C = Top of Haze Layer: 2500 feet

Temperature: 15C, Dewpoint 13C = Top of Haze Layer: 1000 feet

The next time you are flying start looking for the haze layer. It isn’t there every time, but it is there often enough (depending on where you fly).

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Are you on a Collision Course?

When an aircraft approaches you head-on, you are on a collision course. When you are following directly behind a slower plane, you are on a collision course. In these cases, it’s easy to tell that you are on this collision course and you can quickly decide to correct by turning to the right.

But what if another plane approaches at an angle? How can you quickly determine if you will collide or not?

Luckily there is an easy way to figure this out immediately!

Ask yourself,  is the other plane moving across my window? Look at the other plane and which part of your window it is in.

  • If it is not moving then you are on a collision course
  • If it is moving forwards then it will pass in front of you
  • If it is moving backward then it will pass behind you

Note: “Forwards” means that the plane appears to be traveling across your windscreen in its forward direction. “Backwards” means that the plane is moving across your windscreen towards its tail (although in reality it is obviously still going forwards).

You must decide in each situation how to handle it. A good rule of thumb I use is to give way and pass behind the other plane if it only requires a small course correction. This works in most cases and it tends to be safer because the pilot in the other plane may not see you.