Saturday, March 13, 2010

Why is the stall horn sounding.....?

March 10, 2010

The weather this week has been terrific, work has been long hours, I am coming up on a month since the last flight, time to go drill holes in the sky for an afternoon. So I invite one of my daughters, and her friend, to go for a flight. I need to fly at least monthly (or else I need to go rent an instructor for a lap), so I may as well take someone along for the ride.

Krysten (daughter) and my wife took the co-pilot course last fall, and Krysten has not gone for her two rides. This way she can get up for an initial flight, do some handling of the controls, and get some of the shine off so her two lessons with an instructor will be more fruitful.

Unlike the last two flights, the temperature is above zero, +6C. The pre-flight check is not as brutal.

I've not flown this aircraft before. It's a C172M - generally I've flown November models. Review the different V-speeds before climbing aboard, locate all the controls (flap lever and indicator are different), and make sure there are no surprises. The left strobe light is burned out, but otherwise everything is clear.

The flow of the passenger briefings is getting better. During flight training I did very few briefings, so I'm working up to having a "flow".

Start-up, taxi, run-up, backtrack to the button on 09, apply power, gauges checked green, rotate, and we smoothly leave the earth.

As we're climbing out, I notice that we're climbing slower than usual. Mixture is rich, RPMs are good, gauges still green, flaps are not extended, airspeed is good, attitude is normal. Weird, but nothing is out of agreement and things look good out the window.

To the practice area, flying past the casino and the ski hills. Krysten does some straight&level flight. Just north of Wakefield I demonstrate shallow turns, and let Krysten take the yoke. She puts in a bit of a turn (while I manage the yaw with the rudder), and mixes in an assortment of nose-up and nose-down attitude. At 3200' there's lots of time to recover, she gets a bit better over time. There were a few times where we were noticeably nose-down, but the altitude wasn't spinning down, nor the airspeed significantly increasing. Weird.

Megan (in the back seat) is fine, so I do a HASEL check and show them a medium turn (30 degrees of bank) both left and right. Everyone is still happy, so Krysten tries a medium turn - she shows the usual hesitation about putting a "real" bank on the airplane, but does set up for a spiral dive. I have control, and we climb back to 3200'.

I ask them if they want to see a steep turn - warning them that it will likely feel uncomfortable with that much "tilt", and if they look out the side window then there will be lots of air and not much airplane between them and the ground. Gotta love kids, they say go for it. I tell them to speak up the instant they feel uncomfortable, announce our position, do a lookout, and put it into a right steep turn. I wish I flew this well on my flight test, I nailed the nose on the horizon and didn't vary more than 20 feet from altitude.

Everyone is still fine, so I put it over to about 60 degrees, still maintaining altitude. The secret to making a good steep turn is keeping your eyes outside, keeping the nose up on the horizon, and making a quick glance, at most, to the altimeter.

Next stop is towards Ottawa, so Megan can see her apartment building from the air. It will have to be from a bit of a distance since she's inside the Ottawa control zone and I don't have a transponder code.

The Prime Minister's summer residence has a restricted airspace above it to 3500', so I climb to 3900' and head southwest towards the river.

Past the Gatineau Hills it is time to lose some altitude, as we want to fly down the river under the 1500' floor of Terminal's airspace. I brief my passengers that I'll reduce the power to idle, the nose will drop, and we will descend. Everyone is still good.

Partway through the descent (when still plenty high) I point out the VSI and our rate of descent. To get down faster, I tell them about a forward slip being basically plowing the aircraft somewhat sideways through the air, and again, if it feels too weird then say something. Full left rudder, a bit of right aileron to maintain direction, and we plow down through a thousand feet. Remove the slip, descend a bit more to 1300', apply power and fly over the river while the girls try to find Megan's building. Left turn short of the CZ and head east (keeping a sharp watch for traffic heading southeast over the Descehnes Quarry towards CYOW), climb to 1700', pass north of the casino, overhead procedure at CYRO and join the mid-left downwind for 09.

I'm stabilized on final, attitude is normal, flaps are extended, airspeed was about 65-70 knots, and through my headset I hear the stall horn start to sound. Whiskey Tango Foxtrot?

Attitude is good, airspeed is good. Weird. But I put in a bit more power, adjust attitude to stay aimed at the numbers, and get rid of the horn.

Greased the landing, but just left of the centre line. Quick backtrack to Charlie and park the bird.

I discussed the sounding of the stall horn with two instructors after I entered the clubhouse. There was no obvious cause - my attitude and airspeed were good, there were no noticeable gusts... Later that evening I received a phone call - they had taken the plane for a later lesson, and there was a partially blocked static source.

Time: 1.0

Weather: SKC, 10003KT, +06C

Skills: Steep turns, forward slips, normal takeoff and landing

Need to improve:
  • Forgot the check the snags book before flying
  • Forgot to do the rolling instrument check when leaving the apron (I did it after the run up)
  • When doing my 360 check before taking the runway, my wing extended past the stop line.
Done well:
  • Steep turns
  • Forward slip
  • Checking with the passengers - making sure they were comfortable. I hope they felt they could speak up if they were uncomfortable.
  • Reaction to the stall horn. The stall horn was disagreeing with the other instruments, but the worst that would happen with a higher airspeed would be a longer float over the runway. The worst that would happen from ignoring it would be a stall-spin. Though it made no sense (according to the other instruments), I reacted correctly in adding a touch of power and eliminating the horn.

Friday, March 12, 2010

Second Passenger Flight

Friday February 12 2010

So my passenger this time is Heather, a friend (and singing compatriot of my wife). Nancy can't get the time off work. Spousal units, kids and work all coordinated, we head to Rockcliffe.

Heeding advice and lessons learned from my last flight, this one was to be a simple flight to/from the practice area. Heather lives at the southern edge of the practice area, north of CYRP, and so that will be one of our destinations.

Weather was not as brutal as Nancy's flight, it was "only" -14C. Winds were 29008Kt, pretty much down the runways.

Normal take-off at Rockcliffe, pass north of the casino and fly along the Gatineau Hills in the 2000+ range. There was a cloud streamer dead ahead, so I reduced power and ducked under, flying at 1000' (or about 600-800' AGL). On the other side I climbed back up to 1400' (1000' AGL) and flew to Kinburn. From there, Heather, through a hit&miss method. figured out roads and bushes and whatever, and figured out where she lived - reminding me of my first flights in the same area where my instructor was pointing out different towns and roads.

Reduce speed to 70Kt, drop 20 degrees of flaps, and we did a few orbits around Heather's house while she took some pictures.

Off to Carp CYRP where I did a normal crosswind landing (winds about 30 degrees from the right). Well done.

Briefed and performed a short-field take-off, then climb up to 2500' and head back the Heather's for another orbit and more pictures.

Heather than practiced some straight&level flight east, towards Rockcliffe. After about 5 minutes of some pretty decent flight I took over, we headed home to Rockcliffe CYRO, culminating in a normal landing with (unfortunately) a bit of a thunk to the runway - they can't all be greasers.

Time: 1.3

Done well: Overall, this was a clean flight.