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Forward Slip

Forward Slip - Transport Canada photo

The other day I was out flying with my instructor reviewing soft field procedures. We were doing circuits on runway 25, and on the turn from the downwind to base leg of the circuit, we were  hit with strong turbulence every time.  The leg goes close to the river so we assumed it was something to do with that.  It was a bit much for me and I lost my concentration, so I kept coming in too high and fast.  After a few we landed and the controller immediately announced a runway change to runway 16.   I decided that I still wanted to try it, given that the circuits we did on 25 weren’t really that great.

After takeoff from runway 16 the turbulence hit us again only a few hundred feet AGL. I decided that it was probably best to ask for a full stop and end the lesson.  The turbulence was too distracting and kept me from being able to concentrate on the maneuver.  Inadvertently on the landing again, I came in too high.  So my instructor told me to use a forward slip – which is something that I’ve done numerous times – but I hesitated and my mind went blank.  I eventually did it, but think this is a procedure I need to practice still, particularly when I go solo.

What is a forward slip?

It is a turn that is prevented by use of rudder.  The airplane moves in straight, drag inducing position that increases rate of descent and doesn’t increase airspeed – because of all the drag that is created by the airplane in that configuration. The aileron holds the bank while the opposite rudder causes the nose to point in the other direction.

To enter a forward slip, power to idle, turn the aircraft into the wind, and use opposite full rudder. The configuration feels somewhat awkward to me since the airplane is steeply banked and pointing in the other direction. Like everything in flying, it is all about practice until it feels natural!

Another thing is I REALLY need to start bringing my camera and maybe my video camera to my flights! I am always too lazy to take photos but it is great to have them particularly so I can share them here.


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New Aviation Movie Review – Flight – Alaska Airlines Flight 261

Alaska Airlines Flight 261

Flight is based on a real life incident involving Alaska Airlines Flight 261

I recently watched the new aviation – themed movie, Flight starring Denzel Washington.   In it, a troubled airline pilot experiences an in-flight emergency where the horizontal stabilizer jams in the down position, sending the jet into a deep nose dive. Because the captain is a maverick pilot, he is able to miraculously save 102 people through a daring maneuver.  However the accident also forces him to deal with some of his other demons with alcoholism and drug abuse.

I really enjoyed the movie and the rest of the weekend I spent thinking if the flight maneuver was aerodynamically possible.  Basically, he inverted the plane while it was in the steep dive, which managed to arrest the dive and allow him some semblance of control of the aircraft.   Given the stress that is associated with in-flight emergencies, it is doubtful that it could be done.  But is it completely impossible?

Forcing the aircraft into an inverted position when the elevator was down would theoretically cause the aircraft to want to pitch up instead of down. Though because the horizontal stabilizer is now inverted as well the effect would be much lessened. The control of the aircraft from the ailerons would be backwards, and lessened given the fact that the airflow is supposed to be on the top side of the wing and not bottom.  I’m not sure if it’s possible, but probably very aircraft specific.  It’s probably not impossible…but the fact that the airplane doesn’t immediately reassume the nose down position when rolled the right side up after flying upside down? Definitely not realistic. 

It is interesting to note that the accident in this movie is based on a real life incident involving Alaska Airlines in January 2000.

What happened on Alaska Airlines Flight 261.
What happened on Alaska Airlines Flight 261. Photo courtesy of

In this incident, the horizontal stabilizer jammed and the pilots attempted to fly the aircraft inverted – but they didn’t have enough altitude to recover.

In any case, it is a great movie – and I highly recommend it to anyone, particularly aviation enthusiasts like myself.  The figure below shows what happened on Alaska Airlines flight 261.

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Power-off Stalls

How to enter into a stall in Cessna 172.  Why do we learn stalls?

We need to be able to recognize when we are in a stall, to know how to recover. When trained, recovery becomes automatic when trained to react.  Also, we stall the aircraft whenever we land.

I first learned stalls in Edmonton, at CYBW after about 10 hours of flying.

For a power-off stall:

1)  Do your checks. These are a series of checks to do before we are allowed to enter into a stall.

At Centennial flight school in Edmonton we did the “HALT” check, which consisted of:

  • H for Height: make sure we are recovered 2000 feet above ground.
  • A for Area: we are not over a built up area, such as a residential community or over buildings.
  • L for Landing checks: I memorized mine, but they can also be retrieved from your checklist. They consist of: fuel selector valve on both, mixture full rich, carb heat cold, circuit breakers all in, primer in and locked, engine gauges in the green, seat belts on, doors latched, everything tied down in the back and positive pressure on the brakes.
  • T for Turn checks: we do clearing turns to check if the area around us is free of traffic.  We turn at a 30 degree angle of bank 90 degrees to our right, and 90 degrees to our left.

We are ready to enter into a stall.

2) Maintain altitude and heading – keep pulling back on control column to maintain altitude; this will cause the aircraft to loose speed. Use rudder to maintain heading.

3) Confirm approaching stall: buffeting and stall horn – say “approaching the stall”

4) Continue full aft on the control column to stall the aircraft. Do not use ailerons in the stall – they are not effective, and only exacerbate a wing’s tendency to drop.

To recover, immediately:

1) Control column forward: nose down attitude

2) Full Power – carb heat cold

3) Maintain heading and regain altitude

4) Level off into cruise

My instructor told me that we have stalled if we loose over 500 feet of altitude with a lose nose high attitude.

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The short field takeoff and landing with obstacle

Approach and landing over an obstacle

The next maneuver, after mastering the short field procedure, is doing so imagining  having to clear a 50 foot obstacle on both take off and landing. This is accomplished by imagining that there is a 50 foot obstacle at the end of our runway on the takeoff, and that there is a 50 foot obstacle on the start of our runway on the landing.

This short field takeoff and landing with obstacle procedure builds on the skills practiced in the short field takeoff and landing with no obstacle. The objective is to use as little  runway as possible to land and take off, but also to accurately plan our clearance point.  On the takeoff  we need to become airborne as soon as safely possible and climb as fast as possible so we clear our obstacle. This means we need to use Vx, our best angle of climb speed.

On the landing, we have to plan it so we approach so we clear the obstacle and at a proper speed so we still have enough runway to  stop.  The obstacle approach will have us touching down further down the runway then we would if we didn’t have an obstacle to clear, so we have less usable runway. We want to be at a slow enough speed commensurate with safety so we can stop with enough runway.

Ask for clearance

Since I fly out of Springbank airport, which is a controlled airport, I ask for a short delay on departure when I’m holding short of the runway.  In this procedure we line up at the very end of the runway – “on the button.”  Like the short field, we apply full brakes add full power, carb heat cold, check the engine and mixture (if required) and release the brakes.

The speed at which we rotate – or take off – will be given in the aircraft’s POH.  The POH will also give us the climb out speed. For the aircraft I learned on, GSKF, a Cessna 172 N, this is 46 knots. Note that the speed will change with respect to the aircraft’s weight – this is all given in the POH. The POH will also tell you if you need flaps or not for the procedure. For our aircraft I used 10 degrees of flaps.

Short field takeoff and climb with obstacle

Steeper climb-out angle

The main difference is we climb out at a much steeper angle than we did when we didn’t have an obstacle.  This causes the stall horn to sound – which I found disconcerting – but remember, the stall horn sounds 5-10 knots before the stall, so you will have time to ensure you control your speed, and on take-off, our speed is increasing, not decreasing.  Be aware, even though it takes a big longer to stall the aircraft at such high power settings, if you do, this is the dreaded departure stall.

Note clearing the obstacle

We need to mentally ‘note’ where the obstacle is, and to say “clear the obstacle’ once we have cleared it.  At Springbank, the altitude is 3940 feet, so once we are approximately at 4000 feet we announce we are clear the obstacle. The same follows, at 200 feet AGL we announce two positive rates and retract our flaps if we are using them.

More controlled, power-on approach required

The approach for landing is similar to the short field, with flaps – however the objective is to use a power on approach so once we reduce power to idle once we are are clear the obstacle.  We try not to approach too high initially so we decrease power to idle too soon – I made this mistake a few times while practicing, and on the flight test, the examiner wants to see that you know to decrease power once you are clear the obstacle, so they see you understand this is what you are trying to accomplish.

Once clear the obstacle which we imagine is at the start of the runway, we announce it, reduce power, and loose the last bit of altitude, flare and touch down. When we touch down, we push the nose down, retract the flaps, and add heavy brake while applying full back pressure with the control column.

Learning this procedure is challenging, but it is A LOT of fun!

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Short field landing

Short field landing and takeoff procedure explained

At a certain point, your lessons will be about precision flying after you know the basics.  Now my lessons are about more precise flying, not only just about making it down to the ground safely.  Recently I was practicing to aim to land at a particular spot on the runway, using different flap configurations and no flaps.  This was to get used to being precise and prepare for the short field landing technique.

The other day I learned the short field landing method. There are two kinds of short field procedures, with an obstacle (we usually use a 50 foot obstacle) and with no obstacle.  We did the landing without obstacle and next we will do with obstacle, as that is more advanced.   The non-obstacle technique assumes that the runway is clear of obstacles (such as trees or power lines) so we don’t have to worry about clearing anything on our approach or take off.

The short field landing technique is a lot of fun to learn and practice.  It is a specialty procedure that comes in handy when landing at an airport with an unknown runway length or when there are concerns about usable runway length.

We want to plan to use as little runway surface as possible to both take off and land. So on the take off, we line up “on the button” meaning as close to the runway edge as possible.

Short field takeoff

For the Cessna 172, and our particular model, and at Springbank airport, we then follow this takeoff procedure:

  1. Apply full brake
  2. Flaps 10 degrees
  3. Full power
  4. Lean the fuel mixture (check), then mixture full rich
  5. Confirm engine gauges in the green
  6. Release brakes

Once the aircraft starts to roll we steer with rudder to maintain runway centre line. Depending on the aircraft model, we lift off at the recommended speed to fly in ground effect. The particular aircraft we were in, FDAJ, this speed was 46 knots.  We pull up to fly in ground effect, and then push down on the control column to keep from climbing and keep the aircraft level. We fly in ground effect a few feet off the ground without climbing until the airspeed builds to 60 knots, at which point we pitch up and climb out at 65 knots.  We let the aircraft gain 200 feet of altitude AGL. At Springbank the above sea level altitude is 3940 ft, so we wait until our altimeter shows 4140 ft.  We then check for two positive rates on the instruments: one on the vertical speed indicator (VSI) and the altimeter – that is, the VSI is above zero which means the aircraft is in a climb, and that altimeter is increasing which also means the same. We take flaps to 0 degrees, that will establish our speed to 70 knots, and we climb out normally!

Short field Landing

Then there is the landing, which is followed by a full flap approach. In our aircraft we used 30 degrees of flaps and approached at 61 knots as recommended in the aircraft’s pilot operating handbook (POH). We wanted to plan to touch down 500-600 feet after we flared so we look for appropriate runway markers for us to judge this distance. At Springbank, runways 16 and 34 have 500 foot and 1000 foot markers, so it is easy to see our targets.

After we touch down, we apply the brakes – hard. We push the nose of the aircraft down for maximum brake effectiveness and retract the flaps to decrease the lift also to really make those brakes effective.  The first few times I landed I wasn’t aggressive enough on the brakes but eventually got to pushing down on them hard enough. The application of brakes should be so hard you actually are pushed forward and can feel your seat belt.  This is because we are trying to use the minimum runway length possible.

It was really a lot of fun to learn this procedure and I’m excited to try this next time, this time I will be on my own.

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The perfect landing

Normal landing touchdown attitude

The perfect landing technique explained

The most difficult part of learning to fly is, I think, the landing.  It is a precise series of steps that, when individually understood both aerodynamically and intellectually, result in a straight, soft landing no matter the wind conditions.  Since going solo for the first time I have been doing solo circuits, and have really been concentrating on my landing. Unbeknown to me, my landings, though soft are actually not that great.  Once I feel the aircraft sink I have a tendency to let go of the aircraft and let it sink, instead of holding off elevator pressure as long as I can.  This is one of the things that I have really noticed since I began flying solo.

Proper landing procedure

The proper landing procedure always follows a good approach. In the Cessna 172, this is approaching at 70 knots (with zero flaps) or 60 knots (with full flaps).  We can also use different degrees of flaps, such as 10, 20 or 30 depending on the 172 model.  Once we are over the runway threshold, and 2 -3 feet above the ground, we flare – using whatever works for you for knowing when to flare!  – I use the rule of when “the ground starts to come up so fast that something must be done about it.”

Once that is accomplished, you will feel the sink. My issue has been, that once I feel the sink I ‘give up’ and assume the aircraft is ready to land, and let it sink. This can result in a hard landing.  For me, I don’t get the hard landings but  tend to let my nose wheel touch down too soon. This can be dangerous as it can result in wheelbarrowing. The key is to hold the landing attitude as long as possible and bleed off your airspeed slowly.  So once you feel the sink, pull up until you have a very nose high attitude or high angle of attack.  This will cause the aircraft to sink slowly and incrementally. It will allow the main wheels to touch down first, and the landing will be soft.

What are your landings like? Comment below