Archives for April 2005
Low flying 1
Imagine flying along the coast and the weather starts closing in, or it will soon be dark, you’re lost and need to make a precautionary landing. Sounds like an excuse for low flying.
Here in New Zealand (and back at home I guess) it’s illegal to fly below 500′, even over the countryside, except when landing or when the weather forces it. Dotted around are a few areas where low flying is allowed for training, one of which overlaps with the Queenstown parachuting area. Could make this interesting, although a breeze of ten knots this morning and low demand in the off-season means it won’t be a problem today.
The challenge of low flying is, most importantly, not crashing. But also following ground features and choosing a suitable field for landing, if it’s required. On my flight test I’ll need to show I can land within ten minutes which, given the setup can take five minutes, is surprisingly little time.
I’m used to flying at 200′ above the ground but only as a balloon passenger, travelling at a few knots. When moving at 65 knots (that’s about 85mph) things happen much faster.
Nonetheless it’s good fun. After takeoff we climb to just 800′ and the drop down to 400′ after being cleared to enter the low flying zone. It does feel low – lower than I expected – and we move at a fair pace.
Inside the zone some parts of the land are higher than others, so we’ll avoid that if possible. With flaps down and a low airspeed, the aircraft is surprisingly manoueverable but also tends to drop in a turn. Therefore, unlike others parts of flying, we need to use power to control speed, and angle of the nose to control height. Before entering a turn one applies a little power, being the turn, and then bleed the power once happy with what’s happening.
It’s a short but informative lesson and we’re soon heading back to the club. What surprises me most is the effect of drift. With a wind blowing from the side, we need to fly at an angle to our track to keep heading in the correct direction. The result is ‘crabbing’ as we move slightly sideways rather than straight ahead.
Club rules prevent students from doing low flying alone, and I can see why. Hopefully I shan’t need these skills whilst flying solo cross-countries.
(more…)
Air Law
So far I’ve done pretty well at the exams – 100% for Navigation, 97% for Meteorlogy, 96% for radio and 96% for Human Factors. But I hadn’t realised that I’d also need Air Law before doing solo cross-countries, which are rapidly approaching.
The exam was booked at short notice and I spent most of last night cramming. I knew the stuff reasonably well but these were teh most tortuous of legal questions. With a pass mark of 70% I can afford to get eight wrong. But after the exam I know I have five wrong for certain; I won’t know if I’ve passed until I get the results back next week, probably on Thursday.
I’m pretty worried about it, not only for the stupid mistakes (or rather, stupid questions) but also as, if I don’t pass, it will take another two weeks to reapply, resit and wait for the results. In this time I can’t fly solo cross-countries, so my training will effectively come to a stop.
Bugger.
(more…)
Instrument flying
After somemore crosswind practice this morning, a chance to fly with Tim the CFI this afternoon. It’s an opportunity to try something else new – instrument flying.
As a basic PPL I’ll be able to fly cross-country under Visual Flight Rules (VFR), within what are known as Visual Meteorlogical Minima. Basically it means ’steer well clear of clouds’. But sometimes things go wrong and a pilot ends up in cloud, which can be hugely disorientating and very dangerous. With 80% of our balance depending on vision, a loss of horizon makes it hard to know which way is up. What may feel like a climb is straight and level; correct an apparant climb in this situation and you’ll end up in the ground. Similarly, ‘the leans’ occur when a turn feels like straight and level. Bam, hit a mountain.
Therefore the New Zealand syllabus includes five hours of instrument flying. (I’m not sure the UK one does, however.) Obviously we won’t really go into cloud, instead part of the window is blocked off and I’m made to wear a ridiculous-looking hood. the net result is all I can see is the instruments.
The golden rule of instrument flying: trust your instruments (even if the senses disagree). To know what’s happening, it’s vital to keep up a very fast scan rate, Artificial horizon – turn/slip co=ordinator – AH – directiong indicator – AH – altitude – AH – AH – T/S – AH – DI – AH – ALT – AH – T/S – AH – DI – AH – ALT – AH – power etc. It takes place as quickly as you read it. These instruments should provide all the information required.
Heading down to the deep south of the lake (my first departure from controlled airspace – hurrah!) we establish 4000′ and get used to the readings. Then I shut my eyes as Tim takes us through various twists and turns. By the end of that I feel like we’re straight and level but about to turn to the left, whereas we’re actually climbing. It’s very disorientating.
Slipping on the hood (it’s more of a hat, not a balaclava) we strart flying straight and level. I’m chuffed to say that I manage to do this pretty well – all those hours on the Playstation were not wasted – and even climbing, descending and turning were acceptable. It does get harder, however, when entering a steep turn. Everything moves much faster. Not a situation to get into. I also found that as soon as that scan gets broken, even by an idle thought, everything gets lost and its takes a while to recover it. To do this for any length of time would be very tiring. Thank goodness for the autopilot (if only the Tecnam had one!).
I know the area pretty well now and sensed when we were heading back to the airfield. But the hood staye don! We descended to circuit height and Tim issued clear, regular instructions to add or reduce power, pull back etc. I could see powerlines out of the corner of my eye and knew we were doing teh hardest approach of all, R14! Keep banking left…left…hold it straight… and we’re down. I didn’t see a thing, but remove teh hood and we’re taxiing back to the club.
I just hope Tim didn’t have his eyes shut too. Thankfully, he seemed pretty happy with how the lesson went. I’m safe to keep on learning.
(more…)
Advanced stalling
This is where it gets messy! I’d earlier boasted that basic stalling wasn’t all that bad, but today Blair and I are trying advanced stalling. I’m far too sensible to want to get into this situation myself, but when things go wrong, anything could happen.
Almost all lift for an aircraft comes from the wing. Normally the wings are very effective but if they reach an extreme angle to the relative airflow the pressure difference between the top and the bottom – that generates lift – can be interrupted and most of the aerodynamic force lost. The wing ’stalls’ and we drop. To prevent this happening, a stall warning whines when things are about to go wrong. (Or, often, just because it feels like whining, even well outside stall conditions. It can be a bit annoying.)
This can happen at any speed, not just when going slowly, since it depends on the angle of the wing relative to the airflow. It either leads to the aircraft dropping, or one wing stalling first which creates an ‘advanced wing drop stall’ as it lurches to one side, and then the other. Don’t correct it, and it can result in a spin. Not good, unless you’re doing aerobatics.
Solving any stall is, in theory, simple. Stick to push the nose forwards recovering airspeed and lift, rudder to counteract yaw and avoid the roll, and power to regain speed and height.
Naturally it’s something we want to avoid. We climb to 4,500′ and have a good lookout and check before reducing power and puling back the nose. The lack is half obscured by broken cloud, the mountains are capped with snow, the whole scene is stunning. I don’t want to lose sight of it by ploughing into the icy waters, although it would be a nice last view. The stall warning bleats and I start trying to recover, but Blair makes me continue until WAK starts slipping backwards. Stick, power, rudder and we recover immediately. We try a few more stalls in different configurations but I’m always able to catch them early as, of course, I’m expecting them. Plus the Tecnam is a very stable machine that doesn’t wing drop easily.
It’s only when Blair forces a wing drop stall that things get really hair raising. Woosh! All of a sudden a big drop and we’re heading what feels like straight down. He recovers it comfortably but I don’t want to do that again! By this stage it’s time to return and I don’t need to try it myself. Phew.
I’m cleared to go solo in the afternoon but it’s pretty bumpy as I reach 4,500′ and only try three or four before dropping down to try a couple of medium turns and an escape back to the airfield. With the wind rushing down Cecil Peak and bouncing around the lake the Tecnam is shaken up and down, which makes me both physically uncomfortable and uncomfortable about my flying abilities. This is probably a good thing as it reminds me how far I have to go before I’m ready for (dare I speak its name?) the flight test.
(more…)
Short takeoffs and precision landings
Having been spoilt by the mile of asphalt at Queenstown Airport it’s time to see how things are in the real world. If I’m to land in a field on Nimrod Farm I’ll need to be able to complete a precision landing and take off again. I prefer to think of this as my aircraft carrier technique, not that I’d let Naama know!
Rather than a gentle roll down the runway, short take-offs require full power whilst holding the brakes before releasing, achieving require velocity and pulling back on the stick. After a steep climb to clear obstacles, one can level off for a regular ascent. It’s pretty entertaining, adopting a technique I last saw departing La Paz airport in Bolivia where the airliners need all their power to take off from the runway at 12000′ above sea level. Especially the ageing Electras/
Since the Tecnam is a new aircraft for the club, the instructors are sometimes finding their way, hence we tried two techniques. For one, we put the parking brake on, achieved full RPM and then released with a jolt and what feels like a wheelie. With the other, we hold onto the brake by hand (unlike many light aircraft, the brake is like a car hand brake in between the seats) and smoothly release the force. I prefer the latter as it’s a little less unnerving.
Landings are equally good fun, nominating a very precise spot and aiming for it. The setup is slightly different to normal with more flap and a lower airspeed on approach. Errors are not acceptable! Using power to control the descent, we gradually lose height and extent or reduce our approach before a gentle flare.
I’ve rather enjoyed these despite consistenly missing the mark. It may be the sense of accuracy, or different nature of the approach compared to the 1,000 previous circuits, but when going solo in the afternoon I do a couple more than required. Some are within a couple of meteres of the target, but the last one is the worst landing yet! I drop the power to try and reach the mark but I’m too high and drop down. Not adding power, I end up missing my target and geting a thump on landing.
Just my luck that I wsa being watched from the control tower by my instructor…
(more…)
Compass turns
You’d think a degree in Geography should make this easy. But compass turns isn’t just reading a map: it’s moving in three dimensions.
When navigating cross-country the compass is a key tool, and one fo the few items any aircraft must have. The drawback is that it’s prone to errors. Not only do we have to adjust for the difference between true and magnetic north – around 24 degrees here – but also account for the idiosyncracies of turning error. When accelerating or decelerating East or West the compass lags behind and appears to turn even when flying straight, whilst a turn to the North is underindicated, and a turn to the South over indiciated. The net result is, if my mnp shows I want to turn on a map from 090 East to 010 North, I actually need to make a compass turn from 067 to 327. Each heading will be slightly different.
(That’s why aircraft also have a gyroscopic direction heading indicator, but even this suffers different errors and needs to be realigned frequently.)
In the air, flight is further complicated by trying to keep an exact Rate 1 turn, 3 degrees per second. Nevertheless it’s all quite entertaining, and nice to move from just flying up and down to proper navigating.
In the first lesson today we climed to 3,500′ and did several turns. I discovered the trick is to think of the aircraft moving around the compass, rather than the compass moving inside its case. Getting that confused led me to a wrong turn once or twice. The calm weather at altitude – a rare V05 at 2000′ – gave me a chance to do more turns solo in the afternoon, which went well, although the forced landing was once again high. When will I learn?!
With the first snow fall of Autumn still resting on the mountains, the Wakatipu basin looked beautiful.
(more…)
Crosswinds
So far my training has taken place in good weather without much of a breeze. Out in the real world life isn’t like this, and I’ll need to be able to land when a reasonable wind is blowing across the runway as well as down it. Time to look at crosswind landings.
Imagine trying to swim from a boat to shore when there’s a current along the beach. You’ll set out and try and swim in a straight line towards your towel, but swimming at right angles to the beach you’ll still get pushed along the beach by the current and end up further down the sand than you’d planned. The same with a plane. If I line up for a landing on the runway centre line when a wind is blowing across it, I’ll be blown off course. Therefore I need to correct for this drift and fly into the wind, at an angle to the runway, helping me keep the correct path over the ground.
This presents a new problem when landing since I’m no longer facing straight ahead. Therefore I need to gently move the nose straight down the runway whislt avoiding going off track. Just to make things worse, at this point everything I have been taught about using rudder and ailerons together is reversed. Now, if I use right rudder to align the nose, I have to use left aileron to keep on the centre line.
Hmmm. The first lesson didn’t have very strong winds so a few circuits for me to prove my skills on R14. In theory one lands wheel-by-wheel, keeping the wing down to prevent being thrown about by the wind. In this virtually non-existant crosswind things went well on the short runway, even managing to avoid the powerlines.
As another front moved over this afternoon the breeze pcked up and we faced a crosswind of around eight knots. This was a lot more challenging! We took off on R23. Firstly, it was harder to keep straight, especially as I’m also using left aileron to counteract the wind. After takeoff things are pretty bumpy as the aircraft weathercocks into wind. Turning crosswind and then downwind, woosh! we’ve blasted around the turn. The rest of the circuit remains challenging but it’s good fun, even when battling against the wind and the sink at the cliff before the runway. The theory’s there but it will all take practice.
Just to show how things are with a 20 knot crosswind Naama repositioned us on R14. This time we approach at 80kt (compared with the normal 60kt), really crabbing into the wind and then struggling to gain height on the touch and go. Over the riverbed and BUMP! we’re up and down, at one point getting knocked to 75 degrees bank. Woosh! We try again and I’m now well aware of what’s within my limits. Not this, for sure. Lesson learnt.
Crosswinds: hard work, good fun.
(more…)
Solo training to the south
No flying on Thursday afternoon as the wind was picking up but I’ve not trained for crosswind landings. Yet I need to get solo time on forced landings and steep turns so we decided that I’d go up this morning despite winds of 20kt at 2000′. With a 6,000 foot mountain range on one side and a 4,000 foot mountain on the other, this could be bumpy…
Having woken up late I hurried down to the airport and preflighted the plane. Since it was due back at 10am I could only get thirty minutes of flying once the pre-takeoff checks were complete, but that should be enough for now.
I took off on R14 and headed straight to the south, keeping left of the road to avoid the skydivers. I kept on climbing to 4000′ which was rather odd since all of my previous solo time has been in the circuit or doing standard overhead rejoins. Now I’m up here for, well, no particular reason. I felt lost for a few seconds.
Luckily it was not too turbulent so I kept heading south and began some steep turns. Without being hard on myself I must say these weren’t good enough, often dropping 100′ or even gaining height as I tried of correct them. On the plus side I managed to keep the bank correct and the ball stayed in the right place, meaning the plane was balanced, but it was still frustraing. How many times have I used that word now?
The wind was variable from place to place, and starting to get bumpy. At one point the plane dropped and knocked me and my new headset on the canopy, pushing the headset half off. I decided to do one forced landing and head for home.
I landed on R05 with a bit of a bump and taxiied back to the fuel pumps. I was a bit annoyed about it all – after all, I want to do these things properly but didn’t do it well enough today.
My mood was, however, lifted when I looked on the internet for my first exam results. Despite doing the wrong flight plan at first in the Navigation exam, I scored 100% in Navigation and 97% in Meteorology. Pretty pleased with myself although I’m annoyed I didn’t get that last question right in the met exam!
(more…)
Steep turns
It was all going pretty well, then I ended up with something new to learn, new to get wrong.
Thus far I’ve been trying to keep turns below 30 degrees of bank, 15 degrees in a climb, which are gentle and comfortable. Today, however, I have to change that and go for steeper turns at 45 degrees. Tip your head sideways and you’ll realise that’s a reasonable angle.
The physics get a little complicated. As the lift of the wing reduces but the force required increases to keep the plane turning rather than flying off at a tangent. Therefore it wants to slip down, meaning one has to both apply more power and pull back on the column. That sounds fine in principle but in reality I found it rather tricky. In many turns of my turns I lost 100′ or 200′ in the turn. I didn’t appreciate just how much stick it requires, and rudder too. The angle of bank is also disorientating, which feels pretty steep at 45 degrees (or more as I overturn to 60 degrees!).
Therefore when trying to correct this descent I often pull back the stick but also reduce bank to 30 degrees. Sometimes I got it right, other times definitely not. It’s a bit annoying to get it consistently wrong and not effectively correct it. It’s just practice, I know, but I wish I got it right first time. What’s making it difficult is that this is the first new skill I’ve had to learn in a couple of weeks, so it’s reminded me I’m not perfect (yet!).
(more…)
A trip to Branches
Wind at 30 knots at 2000′ so it’s not a day for solo forced landings in the Tecnam. Instead I get a spare seat in a flight down Skippers Canyon to Branches, a small grass strip on a sheep station next to the river.
I was quiet on the trip over for a couple of reasons. Firstly, my new Bose headset had arrived this morning and I was savouring the (relative) silence. Secondly, the landscape is simply stunning. Phenomenal. Impossible to articulate how beautiful it is. Folds of mountains stretch in all directions once clear of the Wakatipu Basin, yet I forgot my camera. (These images are borrowed from NZ Archaeology.) Here’s a typical view of the canyon.
With that wind it was pretty chunky up there, at one point on the way back we were dropping at 1,000 feet per minute desipte being at full power. I’m glad I wasn’t flying!
Branches itself is pretty typical of a rural airstrip, of which there are hundreds around the country. No more than ten feet wide and a few hundred feet long, the approach drops over the hills and across the river before a precision landing. Take off is even more interesting. Backtracking to the threshold and accelerating towards the trees at the end of the runway, we slowly gain speed. When almost at the copice we hit 60kts and bank to the right through a gap in the trees, waiting for the lift. Woosh! Leaves charge towards the windscreen and then we’re climbing rapidly. The airstrip is towards the centre-right of this picture – we landed on the smaller strip before the trees.
New Zealand inspires awe in every direction. It might be easier to navigate and stay straight and level in Kent or Florida, but I can think of no finer place than here in which to learn to fly.
(more…)
