Flying Training
Lesson 29: Spin Recovery
Sunday 2 July 2006, 1.00pm with Kerry Scott in Citabria VH-RRW
Weather forecast: broken cloud above, scattered cloud at our level. Hazy in the distance.
Spins! The cause of many a fatal accident, and the subject of numerous scary stories. And yet pilots (not just aerobatic pilots either) regularly and deliberately enter a spin just for practice. There's been a debate in the instructional community for decades (as I've deduced from books, magazines and online forums) as to whether recovery from a fully-developed spin should be taught in the course of basic flying training, and at Curtis Aviation this lesson is optional. And yet I never really doubted that I would choose to do it. If I didn't, I would always be curious.
The funny thing is, I wasn't even planning to do spins today. I'd decided that if crosswind circuits weren't possible (and they weren't, since there was barely a breath of wind) then short-field takeoffs and landings would be both sedate (after last week's steep turns, spiral dives and other carryings on) and useful (since I seem to be losing my touch at making smooth landings).
I'd spent the morning at Cook Park, watching Alexander score his first goal of the season (and a beautiful goal it was too) against St George in a welcome 6-0 whitewash. Breakfast was a bacon roll. Lunch was a ginger nut biscuit and a small, but as it turned out lethal, flavoured milk. When I arrived, and Kerry stepped out of RRW at the end of a lesson, she brightly said, "It's a lovely day for spins!"
Well, I never back away from a challenge, so I filed away my notes on short field operations and sat in the briefing room where Kerry explained with the help of the company model Citabria just what gyrations we were going to perform. It turned out that it wasn't enough to do a couple of spins from level flight. The plan was to do several of these, followed by a spiral dive for comparison purposes, and then try spinning from a gliding turn, a climbing turn and as many other manouevres as Kerry could think up. And it also appeared that the entry to the spin would involve a complicated manouevre involving a left roll combined with a dive approaching the vertical.
There was more. Apparently one of the exercises involved following an engine restart procedure. Why would the engine need restarting? Well, the aircraft will spin more readily to the left as that's where the torque of the engine is trying to take it. If you choose to enter a spin to the right, that's against the direction of rotation and this may be enough to stop the engine. Hmmm.... Kerry advised that we wouldn't be doing this particular part of the lesson today. However, at least I was able to suggest how we would restart the engine if it did stop (basically, a glide with sufficient speed to turn the prop, and if that fails, try the starter motor).
I'd already taken RRW over, filled it up, returned it to the parking area and carried out the preflight (during which I discovered the stall warning didn't work. And yes, I did have the master switch on, because I was checking the wingtip strobes at the same time), so without any further delay we were off, taxiing for the 24 run-up bay. It was empty, so we picked the furthest bay and went through the run-up checks. I gave the safety briefing as we taxiied to the hold point, and was careful to make a clear and accurate 'ready' call. It wasn't busy, so I had the luxury of lining up and making sure my heels were on the floor before takeoff.
During the takeoff run I had time to contemplate how straightforward this now seemed, and to wonder why I had so much difficulty keeping it straight when I started. Mind you, there's always room for improvement because I caught myself drifting fractionally to the right of the centreline. No matter though, because we were off the ground and climbing upwind towards the training area.
I tried to recall where the 2nm limit
was (so I could climb above 1300 feet), and Kerry demonstrated how I could find
out using the chart. Basically, level off and trim, then you can hold the
stick with thumb and forefinger of the left hand while reaching the chart out
of the door pocket with the right. We were passing Mount Hunter (see the picture), and that's
safely outside the Control Zone, so we recommenced the climb (not forgetting
to lower the nose every 500' to check for traffic), and made a slight turn
right to keep clear of the inbound track from The Oaks. Kerry asked what height
we needed to recover by, and I remembered it was 3000 feet, but Kerry pointed
out that this was AGL,
so we'd be looking to recover by 4000 feet on the altimeter in the vicinity of
The Oaks. You can lose several hundred feet in each turn of a spin, so we climbed
all the way to 5,500 feet. This felt good.
I remembered the HASELL checks (though not as perfectly as I'd remembered them on the ground), and after a 360° clearing turn (during which we spotted Craig's Pitts giving someone the full aerobatic treatment) it was time for the first demonstration. The procedure (say this out loud) was: "Temperature and pressure in the green, mixture full rich, carby heat to hot, power off", then keep the height constant with increasing back pressure as the speed drops to 50 knots (when the stall warning went off. So it does work!). As the speed reduces further to 45 knots and you feel the airframe tremble and control being lost, yank the stick full back and kick in full left rudder. The aircraft rears up, flips sideways and then you're nose down and spinning towards the ground. As I felt my stomach somewhere up near my windpipe, Kerry, calm as anything, was saying "one turn, two turns, stick forward", (the dive became vertical and the spin faster) "full right rudder," (the spinning stopped), "stick back, pull out of the dive and place the nose on the horizon." (At this point I weighed about 300kg.) At the end of the manouevre we were about 700 feet lower than when we started
Since it's so hard to describe, I've found this video of
a spin and recovery in a Decathlon, the Citabria's big brother. Download size is about 2.5Mb, but it's
well worth it. You can hear the engine note drop as the power is reduced, then you can see the nose
rear up and then roll left till the aircraft is upside down and then it does what looks like two full
turns in the spin before the recovery (If you listen carefully you can hear the pilot count them).
The original video is here.
During the second demonstration, Kerry asked my to watch the speed. I found it was distinctly helpful to anticipate the lurch to the left and look in that direction, as otherwise your eyeballs are swivelling uselessly out to the right somewhere. I saw the speed reach 80 knots before we pulled out - pretty fast when you're heading vertically towards the ground, but not in the same class as the spiral dive. Kerry also asked me to watch the turn and slip indicator. The ball shot out to the right, so if you're looking for the direction of the turn, use the turn rather than the slip indicator. In practice it's easy to see which way the aircraft is turning.
Now it was my turn. I found it takes a lot of nerve to kick that rudder in to start the spin, but did it. I was even able to count the turns, and to notice that the slight forward movement of the stick was enough to turn the steep dive into a vertical dive. By the third one, I was able to register that the recovery took half a turn. My only mistake was in entering the second spin, when for some reason my left hand decided of its own volition to pull the trim full back. I believe it thought it was the carby heat, or maybe it was standing in for the left foot which wasn't pressing as hard as it should have done on the pedal, so that this entry was rather indecisive. My right foot, however, was suitably decisive in stopping the spin, and I believe I moved the stick forward the correct (small) distance to unstall the wings. I have a feeling, though, that Kerry would have liked me to pull more G in the pullout from the resulting dive (we pulled 3.5G in her pullout; not sure what it was in mine).
So far so good, but now it was time for a spiral dive. This differed from the last one in that I had to enter it myself. So I checked around, cranked it into a steep turn and continued to pull back on the elevator until I was pressed into my seat and we were headed groundwards at some speed. I felt Kerry pull the throttle off as I started the recovery because we were approaching the red line on the airspeed. Recovery is to unbank the wings and gently pull out of the dive, but I think it would be worth adding "Power off" to the start of the procedure as per the Emergency Manouevre Training book. A subject for discussion with the instructors as it may vary with aircraft type.
Anyway, the spiral dive is where my attention started to wander because I realised that my (albeit very modest) lunch was threatening to put in a reappearance. The next exercise was to recover from an incipient spin, and this I managed fine. The difference is simply that you start the recovery as soon as the aircraft has flipped to the left, and you're unstalled and recovered before even half a turn.
That would probably have been enough for one lesson but ignoring the signs I gave the OK for a spin out of a gliding turn. Kerry had me follow through on the controls but I have little recollection of the exercise because of the rising tide of nausea. I'm afraid Kerry had to pass forward the little bag kept in the back pocket for these situations, and take control while I was out of action. She actually set up an inbound track back to Camden but after I'd tied up the bag and wiped the tears from my eyes I felt well enough to continue with plan B which was a training area check flight, so I flew to Warragamba Dam via Mayfield, pointed out the pipeline, found Bringelly using the crossroads and made my inbound call. I reported over Oran Park and 1800 feet and remained at that height until I was given a sequence (#1) for landing on 24. The approach seemed OK but I ended up with too high a sink rate and Kerry applied some power to arrest it before handing back to me for the landing. It's obviously time for some more landings, which will happen with the next lesson this coming Saturday.
Pre-Area Solo Exam
Instructions
As planned, I sat the pre-area solo theory test, which was extremely comprehensive. The instructions say it all:
- Answer all questions in full
- This paper is designed to test your knowledge of your home base (Camden) and its associated training area.
- Remember, this paper is not just a test of your knowledge, it is a paper to enhance the safety of yourself, your aircraft, fellow aviators and to improve your level of Airmanship.
- Pass Mark 100%. (Failure to achieve this will result in NO flying to the Training Area Solo, until the pass mark has been achieved.)
- Time Limit: 2 Hours
Every time I turned a page there was more. I don't think I've written so much in years. That's Kerry
marking it on the right. I'm afraid I scored a mere 91%, not the required 100% (Cathy likes this pass mark), so when I resit it next week
I need to remember the following:
- Specify whether heights are AMSL (eg airspace limits) or AGL (eg lowest altitude over a built-up area)
- SMC is surface movement control ("Camden Ground") on 121.9Mhz.
- On departure, listen on Camden Tower frequency till abeam the inbound points (so you are aware of inbound traffic).
- When the tower is operating (ie GAAP apply), and you are inbound to 24 from Mayfield, you will join crosswind, not downwind. (CTAF procedures are different, and specify that at least three legs of the circuit are to be flown.)
- In arrival procedure examples when the tower is operating, define clearly the trigger for descending to the circuit height of 1300 feet. It's when the tower gives you a sequencing instruction, or a clearance to land.
- One of the questions asked about "after landing checks". I read this as "pre-landing checks" (ie BUMFISH) and it was marked correct. What are the after landing checks?. (Check POH and training manual.)
- If the radio seems to have failed, remember to troubleshoot first. Check frequency, volume, jacks and headset volume.
- Partial engine failure was an interesting one. Kerry's noted "keep carby heat to hot and throttle at 1/3", but that's what you would do in a full engine failure. It seems that a 'partial engine failure' could cover a wide range of conditions from occasional misfiring to total silence. The clearest response might be to specify some options in each case.
Of course I'm quite comfortable with the 100% pass mark, because I'd like to know that the pilots I'm sharing the airspace with have all this information at instant recall.
Next lesson
Crosswind circuits or (more likely) short field take off and landing
Theory: Pre-Area Solo Exam. Again. Ahem.