Wednesday, January 16, 2008

More crosswind landings and a shutdown blunder

Last Friday I went flying in the early afternoon. The cloud base was definitely above 1000ft, but wind was a concern. As usual when bad weather is forecasted I rang the club before leaving home. Mal asked what I intended to do, I said crosswind circuits, which he was happy to hear since that was pretty much the only thing on the menu in Redcliffe on that day.

We did six landings on runway 07 in the course of 1.1 hour. I did the first one, then Mal demonstrated the second one, which was of great help, and I did all the other ones. We had rain from time to time but not much, and certainly less than the last time.

Before taking off we discussed where the wind would be coming from on all legs of the circuit, and what that would mean for our angle of climb or descent and how we would counter drift in each case. The wind was a south-easterly, which gave us a crosswind coming from the right on take-off and on final.

After lining up I turned the ailerons into the wind to prevent the wind from lifting up the upwind wing during the take-off roll. A few seconds after leaving the ground the plane started to weathercock into the wind. It is a good thing to let the plane turn into the wind a little to counteract the crosswind and track along the extended runway centerline, but not too much otherwise you’ll end up flying straight into the wind!

On the crosswind leg we had a tailwind and therefore an increased groundspeed, which made our angle of climb shallower. As a consequence, it was not possible to reach 1000ft before turning downwind, so I turned downwind at about 800ft and kept climbing.

On downwind the wind came from the left and had to be offset by pointing the nose to the left of where I wanted the plane to go. The turn to base gave us a headwind, which meant that I had to add a bit of extra power to get a lower rate of descent while maintaining an airspeed of 70kt. Mal had me look at the ground to better realize how slow our groundspeed was, and indeed the ground wasn’t moving very fast.

We made the turn to final in such a way as to end up on the upwind side of the extended centreline, i.e. to the right in our case. I pointed the nose to the right of the runway and crabbed it all the way down. I managed to maintain the final speed of 65kt reasonably well.

Prior to entering the plane I had discussed with Mal my initial idea of removing the crab ahead of time in order to not have to do too many things at the same time. He didn’t recommend it, saying it was something that would come later with experience, rather than a useful technique to learn crosswinds.

I did a couple of good landings, and even one where the upwind wheel touched the ground before the other main wheel, followed by the nose wheel. OK, I also did a landing when all three wheels contacted the ground at about the same time, which was less good. And even one where, according to Mal, I was very lucky not to have the tail hit the ground.

I faced a number of problems on that day that need fixing if I want to be able to land safely in strong crosswinds. They’re more or less all related to the timing of the flare.

The first problem was with keeping the nose down and maintaining the 65kt airspeed all the way down final before the flare. I would start to pull the nose up slightly at about 100ft which could potentially bring us dangerously close to the stall speed. My normal scan on short final is to go back and forth between the runway and the airspeed indicator. I think I spent too much time looking at my position with respect of the runway because of the crosswind and didn’t notice the airspeed decrease.

A related problem was that I flared too high on almost every landing. I don’t really understand why, since I had managed to get the flare consistently right in the past on landings where the crosswind component was negligible. My guess is that after I removed the crab I was concerned with not letting the airplane drift downwind, which is why I hurried the landing sequence by flaring too early. Not that it would have made the plane touch the ground any earlier of course.

After landing and clearing the runway we taxied back to the apron making sure to turn the ailerons into the wind. During the shutdown checklist I did one of the most stupid things I have done so far in an airplane.

When doing the magneto check before turning off the engine, I turned the key one notch too far to the left when selecting the right magneto, i.e. to the “off” position. I realised immediately what I had done and turned the key all the way to the “both” position. The engine ran rough for a second or so and then returned to normal. This in itself was no big deal, and is even a normal part of the shutdown sequence on some aircrafts. It is known as a dead-cut check and is supposed to check that the grounding of the magneto switch is correct, i.e. that no magneto is live after shutdown. A bunch of people with a lot more experience than I have discussed the pros and cons of the dead-cut check on

What was really stupid is that I got distracted by this small incident and carried on to switching the engine off using the key, just like a car. The normal procedure is to starve the engine of fuel by bringing the mixture control to the aptly named idle cut-off position. The engine of course eventually stopped after I realised my mistake and pulled the mixture control all the way back. But for a few long seconds the engine made unhappy noises. Maybe it was just fatigue at the end of a demanding hour in the air, but if that’s the case that’s worrying, the flight is only over when the engine is shut down. I still feel upset at myself for doing such a stupid thing.

In summary, some progress made on crosswind landings, but more work still needs to be done, especially on safely controlling the aircraft in the final stage of the landing. Keep the nose down when the runway is approaching, maintain that 65kt airspeed, remove the crab and then flare normally as I would do on any “normal” landing.

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