Day 8 - Lesson 5

Slow Flight / Stalling

Posted by Owain Abraham-Williams on Saturday 1st August 2015

The weather wasn’t looking too good this afternoon, but I was assured the rain would soon pass and the lesson would go ahead. I got chatting to another student at the club who told me he’d gone solo for the first time the previous week. I was thrilled for him and wondered how long it would be before my first solo. I told him how hard I was finding it talking on the radio, he was glad I mentioned this as he was having similar difficulties himself (you can read about my experience in last week’s lesson).

Not long later Derek arrived and we went into one of the briefing rooms to go over the theory behind today’s lesson, we’re going to cover slow flight and stalling. He explained that you would usually only fly slowly if you were lost and wanted to check your map and cross referenced it with what you could see outside. Flying at cruise speed may not give you enough time to plot your position before you had moved somewhere else.

You would never stall an aeroplane intentionally, with the only exception being when learning how a stall feels and what to do to recover from a stall. A stall happens when the airflow over the wing is no longer smooth so cannot generate lift. A stall isn’t to do with flying slowly, it can happen with maximum power set, or even in a descent. A stall occurs when the critical angle of attack is exceeded. It could be just one wing that stalls, in a turn for example.

Just before a stall occurs the stall warner will usually sound and the plane will shudder, once the stall develops the wings will no longer be generating lift and the aeroplane will descend. It may turn, the nose may dip, it may do nothing and just loose height with a nose high attitude.

Slow Flight

We made our way out to the aeroplane and I completed the pre-flight checks, today we were in G-BCJN, the Piper PA-28-140 Cherokee I’d flown in my first lesson. Because of the weather we couldn’t fly South over Cheddar Reservoir as we’d done previously, instead we flew North towards Avon Bridge (this is the M5 motorway bridge over the river Avon near Avonmouth) and then out over the Severn estuary and the two bridges.

Derek demonstrated slow flight by bringing the throttle back, pitching up so as to not loose altitude and trimming to relieve the back pressure on the stick, we were flying at just 60 knots. He showed how with little wind blowing over the control surfaces the controls were sluggish, and in a turn the stall warner may well sound. I had a go and everything went smoothly.

Then we tried very slow flight. Flying with the flaps extended at just 55 knots, only a few knots above stall speed. In this configuration the stall warner was pretty much constant. Turning at this speed is very difficult because the controls are so sloppy and it’s very easy to loose speed in a turn, something you don’t want to do so close to the stall speed.

Stalling

Now we were going to try actually stalling the aeroplane. Before we could do this we had to climb to at least 3,000 feet and run through the HASELL check-list, this is where we check:

  • Height - Sufficient to recover by 3,000 feet
  • Airframe - Brakes off, flaps as required
  • Security - Harness secure, no loose items in cockpit
  • Engine - Temperatures and pressures within limits
  • Location - Clear of built up areas, airfields, controlled airspace, etc.
  • Lookout - 180° left and right clearing turns to check for other aircraft

After a demonstration from Derek it was my turn, I pulled the throttle back to idle and started pulling back on the control column to keep us from descending. Our airspeed decreased and I had to pull right back until I could only see the sky through the windscreen. The stall warner went off, the aeroplane started shuddering and we stalled.

I knew what to do next, I’d read about it in my Flying Training book and Derek and I had gone over the details before my lesson. All I had to do was push forward on the control column to reduce our angle of attack and stop the wing from stalling. Easy. And that’s exactly what I did…

Except I pushed it all the way forward and we snapped round in an instant, going from a nose high stall at about 45 knots with just the blue sky in my field of view to a head-first dive with the ground accelerating towards me at over 120 knots. Derek wrestled the controls from me and recovered us to straight and level flight. We’d lost 1,000 feet!

The 12 second video below shows this stall, unfortunately the camera was not secured properly so it’s rather shaky, noisy and on its side. Also, I’d had a problem connecting the cockpit audio so you can’t hear much, but you can see how everything on the back seat is thrown into the air when I change from a nose-high stall to a dive in under a second.

This experience really shook me. It was the first time in my life I was afraid in an aeroplane. Seeing the ground rush towards me, the urgency in Derek’s voice and the fact we’d lost 1,000 feet in what seemed like an instant really gave me perspective on how dangerous flying could be.

We made our way back to the airfield, flying past Clifton Suspension Bridge and over Bristol city centre. As a resident of Bristol this was a lovely experience, but my “stall death dive” was still very much in my mind. After we landed and were safely back on terra firma I apologised to Derek and went home in search of a stiff drink.

TOTAL FLYING HOURS = 5.7