Never Be 100% Sure

When I was a student pilot I had to fly a night cross-country flight with my instructor. I carefully planned the route and filled out my navlog. We took off in a Cessna 152 and proceeded to the destination, Carol County Airport in Maryland. About halfway through the flight, I was able to see the rotating beacon in the distance and I continued towards it.

I was 100% sure I had found my destination. I descended towards the airport and entered the pattern. As I landed I noticed that the runway number was wrong! This meant that the facility directory must not have been up to date. I taxied off the runway and then my instructor gave me the news. I had landed at York airport, in Pennsylvania. These two airports are 20 miles apart!

If I had not been 100% sure I would still have been evaluating the situation as I flew. That is why I will never tell you that I am more than 99% sure. This is a safeguard to ensure that I keep thinking and taking in new information to find the truth.

A huge 1% difference

My choice to be 100% sure meant that the new information (wrong runway number) was immediately treated as wrong! But if you take the 99% sure attitude, then you will treat new information as the truth and constantly reevaluate what you are seeing. If I had been 99% sure then I would not have put down my map and navlog. Instead, I would have seen rivers and cities and roads all in the wrong place and figured out where I really was.

Runway Width Illusion

There is a fairly common illusion that can make landing more difficult at unfamiliar airports, especially at night. The illusion occurs because we tend to get used to a certain runway width.

When approaching a runway that is narrower than you are used to, you may feel like you are higher than you really are.

This happens as a simple matter of perspective. Your brain uses the size of common objects to interpret your distance to them. However, runways are not common because every is a little bit different. Your brain sees the narrow runway and thinks it is a runway of normal width, only farther away.

Of course, this can be very dangerous as you may contact the runway unexpectedly while you believe you still have some distance to descend. You may land in a flat or even nose down attitude. I have seen students suffer from this illusion many times. Typically, they realize it about one second before touchdown, when I grab the yoke and pull until the plane is in the correct landing attitude.

The illusion also works the other way too. If you are approaching a wider than usual runway it will appear to be closer than it really is. This is not as dangerous as a narrow runway, but still worth avoiding.

As I said above this illusion is far more common at night when it is difficult to see and the runway lights provide most of the information about your height.

How to avoid this illusion

There are several parts to avoiding this illusion.

  1. Briefing. When flying to any airport you have a duty to become familiar with all information relevant to the flight. This includes the width of the runways you expect to land on. Don’t just ignore this detail.
  2. Know the illusions. This illusion is very common at night. It is something you should be prepared for and looking for as you approach any runway at night, especially a narrow one.
  3. Correct immediately. If you believe that you may be experiencing this illusion during landing, correct immediately! Don’t wait to be sure. Just pull back on the yoke to landing attitude and either go around or touch down. If you were wrong, and you really are high above the runway it is often better to go around.

Memory Aid for Nav Lights

Airplane navigation lights are set up to help other aircraft identify your relative direction. A set of nav lights includes:

  • A red light on the left wing
  • A green light on the right wing
  • A white light on the tail

Here is the only memory aid I know for remembering which color is on which side:

“The green light on a traffic light means go which is the right thing to do”

It is kind of muddled up and doesn’t really make sense but I find it to be adequate for remembering that green is on the right.

Do you know a better memory aid for this? Please email me: and I will share your ideas for this one.