Day 45 - Lesson 25

Operating at lower levels / Steep turns

Posted by Owain Abraham-Williams on Saturday 23rd April 2016

Today we’re going to be practising operating at lower levels. This is the type of flying you’d do if the cloud base meant you couldn’t fly higher, or if you’re looking for a suitable field to land in, or even if you’re flying the circuit pattern at an airfield with restricted airspace above it.

Derek briefs me on what to expect, explaining that ground features like hills will be much more noticeable at lower levels. He also explains that the effect the wind has on our flightpath is much more noticeable when we’re closer to the ground. Also, down-drafts from hills need to be considered when we’re flying so close to the ground.

I go out to Tango Lima and run through the pre-flight checks while Derek books us out. The crack in the engine pipe that was discovered after my flight last week really spooked me, so I take extra care today and make sure I read my check list properly and thoroughly inspect each part of the aeroplane.

Take Off

By the time Derek joins me I’ve completed even the internal and starting checks. He apologises for taking his time, explaining that he was talking with Mark, the resident examiner. He takes charge and rushes us down the taxiway in an attempt to make up lost time. But as we turn onto the runway Derek has positioned us facing the wrong way. I point out this error and he calmly turns around and takes off in the correct direction. I can’t quite tell if this was intentional and he was making sure I would challenge authority when safety was at risk, or if he genuinely made a mistake in his haste.

Today Derek wants to demonstrate a short field take off. This is where we use the least amount of runway we can, teaching me the skills needed to operate at airfields with very short runways. This type of take off is a bit of a catch 22; we want to lift off as soon as possible, but we also want to be fast enough to safely climb. The solution is to use ground effect.

When a wing is close to the surface a cushion of air exists that means an aeroplane can fly at lower speeds than it can at altitude - this is called ground effect and is present both when taking off and landing. Usually we just climb out when taking off, but for short fields we can take off and then immediately fly level, building up speed while close to the ground, floating just above the runway in ground effect. With 25° of flaps lowered we can lift off and start making use of the ground effect even sooner than we can with our wing in a clean configuration.

Derek explains that we need to lower the flaps to their second stage, then hold the brakes on while advancing the throttle, only releasing them when the propeller’s RPM has reached maximum. We can lift off at 55 knots (10 knots slower than usual) but once airborne we need to immediately push the control column forward so we don’t climb and can accelerate while in ground effect. Once fast enough we begin our climb and retract the flaps one stage at a time, until we have a clean wing and we’re climbing at 75 knots. We take off, accelerate and climb in just a few hundred metres.

Operating at Lower Levels

After flying over the Mendip Hills and out of Bristol’s controlled airspace we descend to just 600 feet and Derek reminds me that at lower levels we need to be extra vigilant, ensuring we don’t descend too low as things like difficult-to-spot power-lines could cause a hazard. He also says we must always remain aware of our surroundings; higher ground that’s hardly noticeable at altitude could be a significant obstacle this close to the ground.

Our first exercise is to observe the effect prevailing wind has on simple manoeuvres. We cross a drainage ditch, which Derek describes as a rhyne, it’s perpendicular to us and we have a tail wind when we start a rate one turn (a turn limited to 15° of bank angle). By the time we’ve turned through 180° we now have a head-wind and we’ve been blown away from the rhyne; we’ve completed a semi-circle but still have several hundred metres to fly before crossing the rhyne again.

Derek points out that the perspective is quite different at lower levels, even small inclines in the ground are quite noticeable where they wouldn’t be at higher levels. Also, things like Glastonbury Tor are considerable obstacles and we have to keep checking that we’re not drifting towards higher ground.

Then Derek flies us back towards the Mendip Hills and shows how the wind blowing down the hill creates turbulence and causes the plane to sink. Left unchecked this would create a dangerous situation where we’re flying closer and closer towards the ground.

Finally, Derek asks me to do a 180° turn near the hills, once complete he shows how we’ve been blown away from them. If the wind had been southerly we’d have been blown towards them, potentially creating another dangerous situation with limited options. There’s a lot to think about when flying just a few hundred feet above ground.

Steep Turns and Speed Control

Before returning to the airfield, Derek asks me to do some steep turns. He reminds me to do a clearing turn first to check no one else is flying nearby, and that as I turn past 30° I’ll need to put some more throttle in as well as pull back on the control column to avoid descending.

I start with a right-hand turn, remembering to apply more throttle and back pressure. I’d forgotten how steep they feel compared to a normal turn, but I’m pleased with my performance. Then I turn into a left hand steep turn and lose more height than I’d have liked this time. We try it again but still I’m losing height when turning left. I’ll have to practice and perfect this before taking my test.

We then turn towards the airfield and ask for permission to enter controlled airspace. Derek asks me to fly at 70 knots. So I reduce the throttle to about 2,100 RPM while pulling back on the control column to avoid descending. Then I re-trim and adjust the throttle to fly straight and level at 70 knots. Derek seems pleased with this so asks me to fly at 60 knots. This would take us very close to our stall speed, so I put two stages of flaps down to compensate for this, adjust throttle and re-trim. Then I return to flying at cruise speed and retract the flaps.

As I near the airfield and turn onto the base leg Derek asks me to do a powered off approach. I think back to my training last month and delay reducing power until almost ready to turn final. With the throttle idling I descend towards the runway fast. I put the first stage of flaps down, then the second. But I’m descending too quickly and am afraid I won’t make the runway threshold so apply a little power. Finally I put the third stage of flaps down and flare to land. But I flare too high and we end up landing heavily, which really disappoints me. I thought I’d cracked my landings, but it appears not.