Lesson 20 - Saturday April 17th
Some Windy Landings
Friday's lesson was cancelled, so we re-booked for Saturday. The weather Saturday morning was not too good, actually raining. Clouds were pretty solid at 2800 feet, but Tanya told me we'd just be flying in the pattern, and we would only need a ceiling of less than 2000 feet.
It cleared up a bit by the time of the lesson at 3PM, but it was starting to get very windy. Tanya was a bit skeptical about doing pattern work in the wind. The first ATIS we got gave winds as 230/11, gusting 18.
230/11 means wind coming from 230 degrees on the compass, at 11 knots (12.6 mph). Now runway 21 is obviously on a heading of 210 degrees, so that's fairly straight down the runway.
Before we even start the engine Tanya has me call the tower to ask if there were any reports of wind sheer. So I ask this and they say "not at this time". I then ask Tanya what wind sheer is, feeling a bit stupid as I should probably have known that before asking the tower if there was any.
Wind sheer is where the speed of the wind can change drastically at two different heights. You could have a 15 knot head wind at 500 feet, which then changes to 8 knots at 400 feet, resulting in a sudden sinking of the plane, needing a swift application of power to recover.
So, we take off. The first time I get some vibration on my right rudder pedal, and this worries me at first as it feel like we've blown a tire or something, but Tanya does not get the vibration, and we figure out it must have been my foot being a bit high on the pedal and depressing the brake slightly. It does not happen again.
We are just doing left closed traffic. This time I do all of the radio work, as well as flying the plane. I do reasonably well on the crosswind, downwind and base legs, but I'm still a bit hazy when putting everything together for the final leg.
It gets windier as the lesson progresses. But we still seem to land okay each time. Unfortunately I'm not entirely sure why. Maybe half of it is just getting into the right position when you start the final leg of the descent, as then you don't have much room to mess it up, just keep on target and you'll arrive at the right speed.
With the wind being so high and variable, Tanya said we needed to approach at a higher windspeed, 75 instead of 65 on the final. Now since we have a 11 knot headwind, this actually would result in a groundspeed of under 65, so the actually speed when hitting the ground would be slightly less then landing on a calm day at 65 knots airspeed.
We also never put in the third notch of flaps, which is basically what kept us at 75 instead of 65. The extra speed gives you more margin of error in the case of gusts, where you actual air speed could drop 10 knots if you get a strong tail gust. If you were flying at 65, then a 10 knot tail gust (or wind sheer) could practically stall the plane, and certainly greatly reduce lift.
The first couple of landings are fairly straightforward in that we get cleared to land straight away, and can make fairly regular base and final turns at the freeway. It's good to turn base at a consistent distance from the runway, as you then have less variables to worry about.
Later we have to extend our downwind all the way to Century City, so we can follow in a Jet. We let him get a reasonable distance past us before turning base, so we can avoid any wake turbulence, there's quite enough turbulence as it is.
So being on such a long final, I don't actually start to reduce speed until after we have turned final. We've got the PAPI indicator, which is four lights on the runway that change color depending on if you are above or below the ideal landing path. As it happens when we turn base we are just right, so it's actually fairly straightforward from there, just making sure you stay on the path, and reduce your speed as you go.
"Pitch for Speed, Power for height". I'm still not really on top of "Pitch for Speed", as I keep loosing track of the speed as I look solidly out the window. But one thing I really saw today was "Power for height". With the variable winds we would quite often start to sink at an increased rate. Now you can't pull the nose up, as you are descending on reduced power (1500 rpm), and you'd slow down too much, and possibly stall. So to regain height, you just increase power, then adjust pitch if needed to maintain the correct speed. The increased pitch at the same speed with result in increased lift, and will slow your descent rate.
Sounds complicated, but it really all boils down to "Pitch for Speed, Power for Height".
On the last run the winds are up to 15 knots, gusting to 24. Pretty windy! As we are holding short of runway 21, we watch a couple of planes come in. The first one does the usual bump and wobble approaching the runway, and we hear him report "strong gusts at the threshold". We watch the next guy, he also wobbles around, and then we hear him say "we can confirm the strong gusts".
We take off, with the wind so high you get a really high climb rate, and we soar up into the sky, getting to 1400 as I'm turning crosswind (the other day I would not get to 1400 until we turned downwind).
Nobody else around, so we get a normal base turn at the freeway. The final leg is a bit more hectic, with lots of bouncing around, and our sink rate seems more variable. Unfortunately I again fail to keep close track of the speed. We lurch around a lot, my headset bangs against the ceiling a few times. Tanya tells me to adjust the power several times.
We land, with a bit of a bang, but most of the landings today have been like that. Tanya tells me you should expect a bit of hard landing when winds are high. Actually our final touchdowns today seem better than some we've had on calmer days. We bounced a couple of times, but mostly it's been bang, and on the ground.
After we land, Tanya report to the tower that there is a 10 knot wind sheer at the runway threshold. She asks me if I saw the airspeed indicator swing wildly back and forth. I have to admit I did not. I really need to be more aware of my speed, without staring at it all the time.
I feel like I'm not really using the rudder at all, which is something I've felt on the last few lessons. I quite often forget to use it in turns, even though you are supposed to make all turns coordinated with rudder and ailerons. I'll have to talk to Tanya about this.
When we park the plane it's even windier, it's blowing me around as I walk back to the office. Tanya tells me to make sure the plane is tied down tight, in case it blows away. I see the airport police on patrol, probably checking all the planes are tied down properly.
Next lesson Sunday, then another on Monday. Wahay, soon I'll be soloing. Gulp!
(c) 2004 Mick West