Tuesday, November 17, 2009

Displaced Threshold


Yesterday I took a little trip from Santa Rosa (KSTS) to the Cameron Park (O61) airport with a full plane. We were well within weight limits and the tanks were not full so weight in the Mooney was not an issue. I took off toward the east and contacted Oakland Center on 127.80 after reaching my cruise altitude of 5,500 ft. and requested flight following. The controller at Oakland Center was pretty easy to understand and I got a squawk code right away. For those of you non-pilots a squawk code is a unique numeric four-digit code that lets the radar operators know who’s who and what your altitude is. I was handed off to a new controller a total of four times in the short 45 minute flight.

My friend in the right seat wrote down all the new radio frequencies as we made our way. The controller at Travis Approach was not as easy to hear and I had to strain a little for the instructions. The next two controllers from Nor Cal Approach, however, were a different story. Their radios had a whole different tone to them that was very hard to hear. At one point, while almost directly over Sacramento, he gave me a vector (change in direction to avoid traffic) that I could not understand. He became quite upset with me but I finally got him to slow down. He treated me like a child in a demeaning way because I could not understand his auctioneer speed voice. Private pilots are not always required to use Air Traffic Control but always encouraged. It adds another margin of safety. However, many other pilots like me often hesitate because of the impatience and rude attitudes some (certainly not all) controllers have when small planes fly into a certain area. I causes us to not call in at all because of the chance of getting a demeaning or frustrated controller on the radio. We all don’t have super expensive airliner radios or $2,000 headsets. We try to do our best and certainly appreciate the majority of controllers who are patient and understanding.

Cameron Park airport is hard to find and has a very steep approach due to the small valley it resides in. Runway 31 is the preferred runway. Take a careful look at the picture and you can see the numbers "31" about 1/3 of the way down the runway. Basically, final approach skims the side the mountain all the way down staying a few hundred feet above the numerous rooftops built on the hill. It has a displaced threshold that seems as long as the actual runway itself. More on that later.

Landing was a kick. When you make the turn from downwind to base you are directly over a mountain with a holding pond for a top. You're only 200 feet above it. I can't imagine what the winds would do you on a blustery day. Thankfully, yesterday the winds were dead calm. I had one of my best landings ever. I effortlessly floated over the threshold and landed right on the numbers. I nailed it. But I also noticed how short the runway was between the numbers. So I made a quick visual of what I thought the halfway point was for later reference.

There was a Cessna landing behind me so I went to the far end of the runway where there is a circle meant for waiting for just this purpose. Basically, I got out of his way. There’s no control tower In Cameron Park but the other pilot and I were in communication with each other the entire time making clear our intentions. After the Cessna rolled to a stop he turned around on the runway and back taxied. This means he used the runway as a taxiway since there is no taxiway on that end of the runway. It’s a perfectly safe thing to do so long as no one is landing.

As I started to back taxi I noticed a twin engine plane in a low right pattern (not usual) who did not announce himself on the radio at all. Both the Cessna and myself immediately recognized the danger. If he continued and turned to land we may get caught on the runway while he tried to land. We both sped up to get off the runway and tried calling him but there was no answer. Thankfully, the jerk kept flying right downwind and disappeared behind the mountain. I found a place to park and the four of us got out of the plane and off to a concert we went.

We got back to the airport well after dark. The wings were damp with dew and that concerned me a bit due to added drag. It would not be much but I made note of it. I did my usual pre-flight checks and all was well. I did everything without the engine run up as they are prohibited at Cameron Park.

I learned to fly in Minnesota. Never do I recall encountering something called a displaced threshold. My understanding of runway rules, as of yesterday, was no using the threshold for anything other than taxing. My understanding was, also, published runway length does not include the displaced threshold. Those of you who are pilots can already see where this is heading.

Landing on a displaced threshold is prohibited. However, take off is not. But for some unknown reason, I thought it was prohibited. Dumb. In fact, it’s there to actually extend the takeoff roll of an airplane. All airplanes need more runway to take off than to land. At Cameron Park the threshold is 1509 ft long which adds about a third more runway for taking off. My mistake was that upon taking my place at take off, I went to the runway numbers which made my takeoff run 2,349 ft instead of the end of the threshold.

Playing it safe, this would be considered a short field. The plane had 4 passengers but the tanks were not full. The plane was damp so there was more drag. The air was about 41 degrees cool and barometric pressure was 30.12 which was in my favor. Field elevation is 1286 ft. This gave me a density altitude of 248 which is close to sea level. This is because cold air is more dense than warm air. This gives you much better engine performance and more lift. Because the dew was covering the windscreen, I let the plane warm up for about 10 minutes and kicked on the defroster which cleared the windscreen.

Because of my misinformation I taxied out to the runway numbers leaving 1,509 feet of usable runway behind me and 2349 in front of me. But my brain is telling me the published length was 4,051 ft. I knew that could not be right. The other complication was that I was going uphill as the runway has a pretty good dip in the middle then curves up. I thought that maybe since it was night and since I was looking slightly uphill, it was an optical illusion. Thankfully, I opted to play it safe and use a special procedure for a short field take off.

When I hit the halfway point of the runway I was going 65 knots which is 80% of takeoff speed, so, I was on the numbers. I lifted off at 70 knots and stayed in ground effect which is a deceiving pillow of air created by low-wing aircraft. I hit 80 knots, the magic number, and began to gain altitude about 200 feet from the end of the runway. I quickly hit 93 knots (Vx for you pilots) and held her in a climb and then put the plane into a very slight bank to the left to avoid the mountain I knew was looming in the dark ahead. The night was pitch black with no moon and super clear skies. I had to really mind my instruments and know exactly what my plane was doing because, essentially, I was flying IFR (on instruments only) because I had no reference to a horizon. At slow speeds, if you have a full plane and you turn too sharply, you can get into big trouble really fast. So I had to be really careful about what I was doing and remain hyper-vigilant.

I assumed I was on a 4,000 ft runway but my eyes told me it was not. I trusted my eyes. Thankfully the Mooney did what she does best, climb. They’re a small but powerful plane. The entire takeoff roll and climb out took less than a minute. The entire time I’m taking in all my visual clues, monitoring the health of the engine, remembering my takeoff and climb out parameters and recalling my speeds. There’s a lot to do. So you do what you’re trained to do and fly the plane first.

 With a moonless night I wanted as few distractions as possible. So I made my turn and headed toward Santa Rosa (KSTS) and kept climbing until I reached 6,500 before calling the air traffic controllers again. Once again the Nor Cal Approach controllers in Sacramento were jerks. They talked too fast, even thought the skies were not busy and their radios were hard to understand. The controller at Travis Approach, an Air Force Base, was a nice woman who was easy to understand but she was really busy with jumbo jets on the military runway. We didn’t talk much at all. The handoff back to Oakland Center was smooth and easy to hear. I could hear him clear as a bell and he was quite courteous while talking at a normal pace. I was now 15 miles away from Santa Rosa and was in visual site of the airport. I canceled radar coverage and tuned Santa Rosa into my radios.

I set my self up for a 5 mile final approach straight in. There was no one else in the air. On that 5 mile final we saw a large building fire off to our left that turned out to be a horse ranch on fire. A few seconds later we smelled smoke. Had I not seen that fire I would have thought my plane was now on fire for some reason.

I landed on runway 32 in Santa Rosa and we were home.

I have practiced several night short field takeoffs before at Napa. In fact, the weather was much warmer but I had one less passenger. We would land and come to a complete stop on the runway then take off using the other half of the runway. On one of those practice takeoffs my instructor cut the engine on me just 300 ft. above the ground just to see how I would react.

Executed properly, there’s nothing wrong with doing a short field takeoff. In fact, pilots practice them all the time. They are not hard to do, just a little different. In this case, everything went perfectly. But I wasn’t practicing short filed takeoffs. This was the real deal. My mistake was leaving a 1,500 ft. margin of error behind me. It’s said the two most useless things for a pilot are the air above you and the runway behind you. I won’t make that mistake again.

I think I picked up my misinformation about displaced thresholds from my early training. I seem to recall learning about it but I misinterpreted that displaced thresholds are only for taxiing. That information has been stuck in my brain for 25 years. I've never seen such a long displaced threshold than at the Cameron Park airport and certainly, up until yesterday, have never had to use one.

Lesson learned.

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