HOUSTON (CW39) – As a meteorologist I am always studying the sky, but today I will be in the sky with Texas Southern University’s Flight school. Costa shows me the airways, and we discuss how the weather impacts aviation. Costa Papanicolaou is the Chief Pilot at Texas Southern University who has a deep knowledge of the weather due to how much aviation and atmospheric thermodynamics overlap.
Part 1: Takeoff
The thermodynamics of how a plane gets up into the sky is a mystery to a lot of people, but there is science behind it. The science behind it correlates very well to the weather, and our day-to-day weather. We have high and low pressures that form around the plane. Can you explain how that gets the plane up?
Costa says, “I guess in very simple terms, we have a principle called the Bernoulli Principle. Basically, what it is telling us, is that as molecules move faster, their pressure (the pressure of that air mass), will decrease. We have air moving on top of the wing, which as you can see is a very curved surface, and there is air moving underneath the wing. The air moving under the wing will have a higher pressure than the air moving above it. That discrepancy between low and high is what pulls the airplane up. So, we think of lift as a force that pulls the airplane up, not by pushing it, but by sort of drawing it up into the air based on this Bernoulli Principle.
And that plane you saw taking off there… Guess who is inside!
Costa adds, “We want to stay at the very minimum 10 miles away from any thunderstorm cell. These cells are made up of rising and falling columns of air. Those columns of air are moving very, very quickly! As the flow comes down it can spread, causing all sorts of bad stuff!”.
For example… a microburst! A capable of strong winds and little to no warning. Therefore, it is always important to pay attention to the days forecast before takeoff.
“As the temperature increases, so does the density altitude. Planes just don’t perform as well at higher altitudes. When we are rolling down the runway and it is 50 degrees outside, the airplane really knows where it is right! It has a lot of density, producing all that lift. It is great! As we get into out Houston temperatures, the 90s… suddenly, the airplane is running down the runway as if it is at 3,000 feet. This will cause it to run a little bit worse.”, says Costa.
And before takeoff you don’t want things to be too cold either.
He adds, “Then, we have to start worrying about icing forming on the wings, forming on parts of the aircraft fuel silage, and so on. Those are things we try to mitigate with various forms of technology whether that be chemical technology or electrical. We try to find solutions to those problems so that we can always be in the air.”
Speaking of solutions… what is in the de-icing solution that makes it so useful in getting the ice off the plane, or preventing the ice from forming onto the plane?
Costa laughs, “What you are asking now is a chemical question which is outside my expertise! I can tell you however, what it does… It changes the freezing temperature. There are various glycerides … I have to think back to my high school chemistry class!”
He added that, “It is a mixture of chemicals, which when applied changes the temperature at which ice forms.”
This is the same reason we apply salt to the roadways. The salt will lower the freezing point.
Next, we cruise the sky and talk about the weather’s role in getting back down to earth.
Part 2: Descent/Landing
“We start off with whatever the ambient temperature is on the ground. We lose about 2-3 degrees per 1,000 feet. Which is great because it cools us off a little bit. Thinking about Houston here… We are starting off around 90 degrees. Anywhere below around 3,000 feet you are going to have to encounter a phenomenon which is basically these rising columns of air coming off objects like concrete or buildings, that are trapping that heat. We end up having a bumpy ride on the way down to the lower altitudes. We are traversing an area that is initially a lot of concrete such as an urban area. Next thing you know you hit a pocket of trees or foliage which are not causing as much as a rising column of air. So, we are just bouncing around. Particularly when coming in for a landing.”, says Costa.
Since you are up in the sky, closer to the sun, do you ever have to worry about being blinded by the sunlight? The aviators are a popular pilot fashion trend. Does it ever occur to you, the importance of really watching out for your eyes?
“You absolutely do! It seems like it is a minor point, but it is not! If you are blinded, a short final this is a big issue. We do always wear our sunglasses, and I appreciate that they are somewhat fashionable. At the end of the day, they are a tool. Just like anything else. You will see pilots wear them even on cloudy days. We do have, a lot of times, glare that we want to mitigate. We want to be in the safest environment that we can be. It is a consideration. Sometimes you may even consider an alternate runway because maybe you are going right into the sun on a landing.” says Costa.
What other factors will cause a last-minute change in plans when going in for a landing?
“It can be a number of things. One that people don’t think about… if you look out at the actual acreage that the airport is. There is wildlife out here sometime.”, says Costa.
I was going to ask if you ever had a gator cross the runway!
“We have seen all kinds of unusual things. I’ve been on short final where suddenly there is a turtle making its way across. That is going to cause a rejected landing. I’ve seen deer cross; I’ve seen all kinds of animals moving around. It is just one of those things that you must keep an eye on and be ready for.”, he adds.
You are at the level where birds are flying, have you ever encountered wildlife in the sky. Not only on the runway, but in the air?
“All the time…”, says Costa.
“All the time we see the birds up there. It is a very rare phenomenon that you have a bird strike as we call it. Where the bird and the plane make contact, very rare. What I tell my students, is that the birds know how to fly just fine, don’ t try to stay out of their way or do. Anything out of the ordinary, the birds will duck and dive away.”, Costa adds.
Pull back… HARDER! Costa tells me as I come in for the landing.
I landed the plane!
This was a day of working in the weather that I will not forget.