Saturday, 23 February 2013

Flying in wave

At long last we have had our phase 1 exam results. From what I have heard so far, everyone in the class has passed which is great news, though I won't know for sure until Monday. I was very pleased with my own results, which were actually better than both the school finals and my expectations. Onward to phase 2...

I have two fun flying-related tales to tell you about today — my first experience gliding in wave and my familiarisation flight to Milan a few weeks ago. First the gliding.

This is how the average power pilot sees wave - hazardous!

What is wave?

Mountain wave is an atmospheric phenomenon caused basically by wind blowing across a large ridge or chain of mountains. Obviously enough, the hills force the air to rise as they pass over, and if it is stable it sinks again on the leeward side.

Less obvious is that in the right conditions this rise and fall can continue and intensify downwind of the mountains. The effect can reach up many times the height of the hills themselves. Technically the air is in resonance, which is to say it is bouncing up and down a bit like a spring.

Wave can be a good or bad thing, depending on your perspective. When we have studied mountain wave in ground school, it is presented as a dangerous "avoid at all costs" hazard that can cause damaging turbulence, difficulties in controlling the plane and even make it difficult or impossible to climb away. True enough, it can.

This is how the average glider pilot sees wave - miraculous!
But wave also means lots of rising air, and when that happens, glider pilots are never far away. Yes, believe it or not us crazy glider pilot in our tiny, floppy, engine-less planes actively seek out and fly in mountain wave conditions.

Incredible heights can be achieved this way, and impossible distances covered by the skilful pilot. The UK height record in wave is an amazing 38600' set at the Deeside Gliding Club in Aboyne, Aberdeenshire. This is the same sort of height as your passenger jet cruises. 

In the Andes, the record is a mind boggling 50,671' (see the Perlan Project) and distances over 2000km have been covered in a single flight. They are now aiming for 90,000' in the world's first pressurised glider!

So let's give it a try...

I finally got to try wave flying myself last week, at Aboyne. I was incredibly lucky with the weather, which was mild and sunny with a gentle north-westerly wind blowing. From the forecast, it looked like the wind was too gentle for much wave to form. But as we slowly got all the planes out of the hanger and inspected, got our briefings from the instructors and were ready to fly, a few weak lenticular clouds were starting to appear towards the north.

A lenticular cloud is a distinctively smooth, allegedly lentil-shaped cloud that is associated with the rising parts of mountain waves (see image above). They are strange in that they remain stationary in the sky despite the wind whistling through them — the cloud forms on the windward side and vanishes on the leeward.

I was, frankly, a bit nervous. I hadn't flown since October and there I was poised at the end of an laughably narrow runway about to deliberately aerotow up through potentially violent turbulence. Well, nothing ventured nothing gained!

The tow was certainly lively and both us and the tug plane were bounced around a fair bit, but it was no worse than a strong thermal day back home and I coped fine. Meanwhile, my instructor Mike in the back used his 50 years of gliding experience to direct the tug pilot to where he thought the lift would be.

Suddenly we hit the 'rotor' — and real turbulence. As we were both the sky it took all my concentration (and all of the control deflection) to keep rough station behind the madly bobbing tug plane. At the same time, I was supposed to be watching the vario (vertical speed indicator) to see when our usual climb rate of 4-6 knots rose to 8-10, indicating upward wave. And this was in gentle winds!

Just as suddenly the air went silky smooth and quiet, leaving just the vario beeping madly away to itself. I released the tow rope at 3300' and there we were, gently and serenely climbing at about 2 knots as if by magic.

Lenticular clouds lying in a wave pattern over the Grampians. As a 'flat-lands' glider pilot, I don't
often get to look down on clouds!

I spent some time exploring the air to find the best lift and getting my bearings. Gradually I developed a pattern of S-turns that kept us in the lift, flying dead slow in the eerie quiet between turns. Before long we were over 8000' — smashing my previous PB of 6400' — and with incredible views of the Grampians and Lochnagar.

Gradually we became aware of another, independent wave system building above us, and tried to transition into it but didn't quite manage it. We explored up the Dee valley to Ballater too, but the wave formations were starting to break up and weaken. We heard on the radio that Mike had more customers and we had been flying for and hour and a half — which had flown by — and it was time to head back.

Lochnagar peeking out of the wave clouds
With 4000' to spare over the airfield, I persuaded Mike to let me use some of the height to do the upper air exercises that form part of every glider pilot's annual checks. I practised stalling straight and level, accelerated stalls and stalling out of a turn followed by some full spins and recoveries.

Spinning is another area where power pilots must think we are mad — to a power pilot a spin is a dangerous manoeuvre to be avoided at all costs. To a glider pilot, who spends a lot of time flying slowly in tight circles, an accidental spin is a real possibility and should therefore be practised regularly. They are also fun, in a strange kind of way. Yes, spinning round rapidly with the nose pointing straight down is very frightening, at first (this is what it looks like). But knowing the recovery technique and knowing that it really works is very satisfying.

Down to earth

Every flight ends (one hopes) with a landing, and with a bit of prompting from Mike I executed a scruffy but effective circuit in the unfamiliar landscape and lined up with the long but ludicrously narrow south runway. My instructions were to land deep and roll right to the other end and — whatever happens — stay on the black stuff as the surrounding grass was very rough.

I am accustomed to a 150m wide grass strip, so to me this silly little 4.5m ribbon of tarmac looked impossibly tiny. Fortunately there was only a little crosswind and I found it wasn't difficult after all. I rolled as far as I could, ending up a few metres short of the target line. Apparently the fine for this is one dram per foot to the club chairman, but as I was a visitor they let me off!

About to touch down on the titchy runway
Well that was quite a day, and I think quite enough for one blog. My front-seat ride to Milan will have to wait until next time.

A big thank you to Mike and everyone at Aboyne for their time and making me feel so welcome. I will be back.

Thursday, 7 February 2013

Exams over II!

This is just a quick progress update...

We have just walked out of the last of our seven phase one written exams - it's all over!

Unfortunately due to some questionable planning on my part I can't head straight for the pub with the others as I have not one but two medicals to endure this afternoon; one for EASA (Europe official aviation bods) and one for the FAA (American equivalent).

Pilots often get stressed about medicals as their jobs and future rely on the outcome, but after a week like this I don't have any capacity to worry left.

The subjects we have been examined on were:
  • Principles of Flight. This is essentially physics and aerodynamics with the focus on aspects that are important to piloting and safety
  • Airframe systems and propulsion. This is a bit of 'dumping ground' of a subject including diverse material such as structures, electrics and engines, but the main bulk is understanding all the systems on a modern passenger jet. A big subject.
  • Instrumentation starts with basic old fashioned pressure instruments and continues right up to the latest flight management computers and electronic displays and autoflight. It is a minefield of acronyms, most of which start with A and many of which actually stand for other acronyms...
  • Meteorology another big subject that goes into surprising detail about local winds and climates as well as the bigger picture of how weather is generated, and how it affects aircraft.
  • Human Performance looks at physiology and psychology and ask what lessons we can learn for better flying and flight safety.
  • Finally VFR and IFR communications. This is radio technique and associated knowledge (VFR is flying when you can see where you are going, IFR is when you may not be able to).
 In total that makes 8.5 hours of exams over four days, pretty exhausting. It represents three solid months of study and revision.

Just over half of ground school is now completed which is a good feeling, and also marks the start of a welcome two-week break.

Some football player or other enduring a similar
medical examination
I think they went pretty well, with only a handful of questions in each subject being unfamiliar or ambiguous. Being multiple choice exams, it's generally possible to have a good guess even if you are not certain by eliminating the incorrect answers; but you do need a bit of luck on your side.

Last week I was fortunate enough to experience a 'familiarisation flight' with a British Airways crew, flying to Milan and back in the cockpit 'jumpseat'. I will write up this fascinating trip very soon, but just now I am off to get drunk poked and prodded by the aviation medical examiner.