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Kit plane landing on a ship at sea

Foxbat lands on cargo ship

I recently watched the video of one of the most impressive landing and take off I have ever seen – a small plane landing on a ship at sea.  This is right up there with the video of the Piper Cub that landed and took off on a mountain ridge.

Aerobakt Foxbat. Image from wikipedia
Aerobakt Foxbat. Image from wikipedia

The pilot of an Aeroprakt A-22 Foxbat Xtreme, a British-registered kit plane, ident G-CWTD manoeuvres the plane over a landing strip of an aircraft carrier that is not more than 275 feet long.

The ship is an M2 Runner cargo ship.  It’s length overall is 92.9 meters – or 305 feet. The length between the towers at the front and back is 84 meters – only 275 feet! Have you done your short field specialty take off and landings, especially those with obstacle, you will know that you have to calculate the amount of runway you will need to take off and land, and use special procedures to maximize the runway. But this is ridiculous.   The Cessna 172 that I fly will require around 500 feet for the short field procedures.  How is this possible?

Well if you watch the video, you will notice that the ship is sailing. The stall speed of the Foxbat is only 28-30  knots.  The low stall speed means that the plane is able to fly quite slow before stalling. Compare this to the stall speed of a Cessna 172, which is around 47 knots (of course this will vary depending on weight, centre of gravity and so on).  The Foxbat will stall at almost 20 knots slower.

The M2 Runner, like the one used for the landing and takeoff.
The M2 Runner, like the one used for the landing and takeoff.

I don’t know much about cargo ships, but I researched that they generally cruise at speeds between 20-26 knots.  Thanks to the pilot of the Foxbat, who contacted me and corrected me that the speed of this ship was only 9 knots – and in good conditions, the maximum speed is 13 knots.  This means the plane will have to fly at least that fast, and obviously above it’s stall speed, to keep up with the ship.  If there was a strong headwind, this would help him as well.  Remember it’s not the actual speed of the aircraft will determine when the plane will stall.

So how is he able to fly like this?  So the ship is moving forward at 9 knots, and there is also a headwind, then depending on the strength of the headwind the Foxbat should be able to fly above stall speed and it will appear as if he is hovering over the runway.  He is obviously flying well within approach limits given the amount of control he has.

In the 172 we approach at 60 knots (with flaps) and 70 knots without flaps, and generally land at around 50 knots or so. Flaps will help him fly slower If we assume his approach but it doesn’t look like he is using them in this approach. When we perform a short field landing, we hit the brakes really hard. Because of the ships movement, the plane touching down will have the same affect as hitting the brakes.  Timing has to be perfect …  Take a look at the video:

At the last minute, the pilot veers in front of the ships tower in the back, lines up and bounces down on the ground. It looks like he still is able to land at the back half of of his “runway.”

The takeoff is even more impressive.  Spooling his engines, he has several people hold the plane down (as he is no doubt pressing on his brakes as hard as he can). Then he lifts off, and looks like he used only 50 feet of runway or so.

This is a very impressive display of extreme piloting. This guy is an excellent pilot, and also a bit of a daredevil. He is definitely taking a risk by demonstrating this procedure.

I recently had the pleasure of speaking with the pilot, and though he said it was a dream come true, and things just came together to make this happen as the owner of the ship is a good friend of his – he wouldn’t do it again.

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Flying on instruments

Cessna 172 instrument panel

I’ve recently learned the basics of flying on instruments. First in the simulator and went on my first flight “under the hood” the other day.  It adds a whole new dimension of complexity to flying. Just when you start feeling you have a pretty good handle on things, on comes the hood, and you’ve lost reference to the ground – and you are feeling like your world is quite small in the cockpit, with only your six pack of instruments, compass, navigation equipment and other cockpit items in front of you.  No looking out your window … even if your instructor tries to tempt you, saying a 737 is passing overtop of you!

Why do private pilots need instrument time?

Transport Canada requires that private pilots receive 5 hours of instrument training, 3 of which may be in the simulator.  Why do they do this?  Getting a little bit of time “under the hood” can prepare you to deal with the worst should it ever happen to you. As VFR pilots with no night or instrument rating, we are not allowed to fly around in IMC (instrument meteorological conditions).  But sometimes the worst can happen and we may inadvertently enter cloud or get caught up in bad weather where we loose visual reference to the ground.

How to scan the instruments for different manoeuvres.
How to scan the instruments for different manoeuvres.

How do you fly on instruments?

The basics are explained very well in Transport Canada’s Flight Training Manual. In the airplane, we use a cover known as the “hood” and instrument flight is simulated with your instructor keeping an eye on the outside in VFR conditions. The main part has to do with understanding your control instruments and your performance instruments.

Attitude + Power = Performance

Your control instruments are Attitude Indicator (AI) and your tachometer (or Manifold Pressure Gauge). The combination of these two instruments will give us performance, measured by the performance instruments, shown in the Airspeeed Indicator (ASI), Turn and Bank Coordinator (TC), Heading Indicator, Altimeter and Vertical Speed Indicator (VSI).

The basic formula of attitude + power = performance stems from the relationship that any combination of different aircraft attitudes, coupled with a power setting will cause you to increase, maintain or reduce airspeed, altitude, turn and bank, heading and vertical speed.  These five instruments can be referenced as indicators, or outcomes of changes in power or attitude.  Some instruments are better than others to show these changes, and is known as the “scan”, which allows you to identify which instruments you should reference for what.

The attitude indicator is the heart of our scan. Because we have no outside reference to the horizon, it will tell us when we are flying straight and level and when we are banked, and reference it when we expect to be in a climb or descent.

To illustrate, recall that a nose down attitude coupled with a low power setting will cause a descent, (loss of altitude), a nose high and high power setting will create a climb, (gain in altitude).

To develop the procedures to refer to the proper instruments at the right time, always ask yourself the questions:

  • What information do I need?
  • Which instruments give me my needed information?
  • Is this information reliable?

Doing an instrument scan is how you use the technique.   There are a number of different scans depending on the information you need. For example:

Under the hood.  Just completed a simulated ILS approach for runway 35.
Under the hood. Just completed a simulated ILS approach for runway 35.

1. Straight and Level Flight: mainly attitude indicator, altimeter and heading indicator

2. Straight Climb: mainly attitude indicator, heading indicator and airspeed indicator

3.  Approaching desired altitude:  mainly attitude indicator, altimeter and heading indicator

4. Level, approaching desired airspeed: mainly attitude indicator, altimeter, heading indicator and airspeed indicator

What if our vacuum system fails? We will loose the vacuum-system (engine powered) instruments: the heading indicator and the attitude indicator. Since the attitude indicator is a very important instrument for us, we have to be very careful and apply the partial panel technique. Stay tuned for this in our next post.

Simulating an ILS Approach

When I went under the hood for the first time, my instructor asked me if I wanted to simulate an ILS approach for runway 35.  He helped me out and I flew the approach, simulating an approach in IFR conditions.  When he asked me to remove the hood, I was 200 AGL and the runway was just slightly to the right, about 1/4 nautical mile in front of us. I got us back on to centreline and did a nice, gentle landing. The ILS flying make me hyper aware and very sharp. It was a lot of fun!

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Wind and performance

At Springbank airport, we are very mountain effected and often have to deal with heavy winds.  Speaking of winds, we found the most amazing landing and takeoff video we have ever seen.  In this video, the brave Super Cub pilot, lands on the shoulder of a mountain in Central Nevada at 11,000 feet.  The landing on Bunker Mountain is spectacular, but the take off is even better.  You can see that his plane is equipped for rough ground landings given the large tundra tires.  These are large, low pressure tires to allow operation on rough terrain on light aircraft. And rough terrain it is, the pilot lands on a talus slope.

The description says that it was very windy on that mountain. No doubt, he was landing into the wind, which allowed a very short landing and takeoff roll.  The pilot is very skilled, you can see he dips his wing into the direction of the wind and returns to straight and level flight at the moment before touchdown.

Importance of winds to pilots

Winds are one of the most important things to understand when it comes to flying.  Pilots have a very intimate relationship with the wind, it governs our go-no go decision, most importantly in terms of our take off and landing considerations.

Why does wind affect performance? Because our aircraft relies on the difference in pressures between the lower wing and upper wing in order to obtain lift, and remember it is always the relative wind that matters. So if there is zero wind, your aircraft will require more ground roll to lift off then if there was an headwind component. Why? Because it’s the relative wind that matters. For example, recall the relationship between stalls and angle of attack.

Recall in your POH that when calculating take off distance, you reduce your ground roll according to the amount of headwind you have.  In the Cessna 172N, you decrease the ground roll by 10% for every 9 knots of headwind.  This is because the headwind adds to the flow of air over your wings, air flow that otherwise you would have to generate with power.

The high altitude would have made the take off and landing roll longer, but it appears as if the winds were sufficiently strong enough to allow a shorter roll. And I do mean short!

I found the relationship with the wind is also strong when you ride a motorcycle.  And it is a commonly known fact that many pilots do love motorcycles.

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Crosswind takeoffs

What about the take-off?

Since the take-off comes before the landing, shouldn’t we know how to take-off in a crosswind before we learn how to land in one?  Well, yes, but there is a big difference in consequences between the two.  We can always abort a takeoff (choose not to go flying that day) if we feel the conditions are not right, but once we are flying, we can’t choose not to land. Though it’s true that we can choose an alternate airport if winds are too strong to land in, and we absolutely should if we don’t feel it’s safe to land, but we should be able to land in a crosswind with proficiency if the situation arises.  It is a normal part of flying and should be practiced until it presents no difficulty.

During the takeoff, directional control is maintained with rudder, just as in a normal takeoff.  Depending on the strength of the wind, you may need more rudder than normal.   Ailerons are deflected into the wind, which counters the tendency for the upwind wing to be lifted by the wing and rise.

To take off in a crosswind, recall that when we taxi in a crosswind we use wind inputs.  As you add power, keep these inputs in all the way, and remember to add right rudder.  As your aircraft accelerates slowly neutralize the ailerons and release the wind inputs you need on the ground.   Anticipate adding your wind inputs as you get airborne to keep from blowing off the runway.

Remember, you want your runway directly behind you.  Enter into a slip, the same as when approaching in a crosswind.  Aileron into the wind – upwind wing dipped into the wind – and enough rudder to keep the longitudinal of the axis straight and aligned with your track on the ground.

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How to land in a crosswind

Crosswind landings are one of the most frightening thing to learn for student pilots.  For me, crosswind landings were one of the most challenging manoeuvres and probably took me the longest to perform proficiently.  This is because they absolutely have to be mastered – you simply cannot fly and not be able to do this. But also with cross wind landings, experience is everything, and the more you do these the better you will be at them, and the more comfortable you will feel.

In the beginning when you are only flying with your instructor (dual), they make sure you are very comfortable and proficient at cross wind take offs and landings. Though on your first solo it is highly unlikely you will be sent up in any crosswind, you have to be prepared.   What if the surface wind changes when you are in the air?  You are on your own.

There are two basic cross wind landing techniques. They are:

  1. Side Slip (or wing-low) landing
  2. The Crab

The Side Slip

The most popular cross wind landing technique and the easiest is the side slip (different than a forward slip).  This is the first one you will encounter when you are learning. In fact, in North American for flight training the side slip is preferred and the crab is largely ignored, until you get into more advanced training and more complex aircraft. The nice thing with a side slip is that the longitudinal axis of the aircraft is already aligned with the runway, so there is no need to straighten out the aircraft before touchdown. This makes the procedure slightly less overwhelming then a a crab.

Cross wind landing techniques. Image from Flying Magazine.
Cross wind landing techniques. Image from Flying Magazine.

In a side slip, the longitudinal axis of the aircraft should be aligned with the runway and one wing, the upwind wing will be pointed down.  To enter into a side slip, dip your upwind wing down into the wind, and apply opposite rudder sufficient enough to keep you aligned with the runway and from turning.  You will have to adjust the amount of bank required to keep you flying in a straight line.  Too much bank and the plane will move into the wind, too little and it will drift with the wind.

You hold these inputs until the flare, and hold off until the airplane is landed in exactly your approach configuration: you will land on the upwind wheel first.  This is awkward at first, but this is usually brief as the downwind wing follows soon after.

Remember that when we are landing we have to use right rudder to counteract left turning tendencies, so anticipate this and factor it into the amount of rudder you will need when both wheels are on the ground.

Wind gusts will make it more challenging

When the wind is gusty, you will have to adjust your inputs to keep you on track.  This is a tricky thing to learn and takes some time.  If you practice often, you will get a good feel of how to keep the aircraft under control in gusty conditions.

The challenge with side slips is they don’t work for all aircraft types, whereas the crab works for all aircraft.  They are also not suitable for instrument approaches (ILS) or gliding for range.

The Crab

The crab is more advanced because the configuration has to be changed just prior to touchdown.  In the figure above note that your aircraft is not pointing straight in a crab approach – it is not aligned with the runway. This means that prior to touchdown, you have to release the rudder inputs to avoid cross loading the landing gear.

To enter a crab,  point the nose into the wind and maintain wings level.  Your nose will be pointed into the wind, unlike a slip, and your wings will not be dipped but level. Just prior to your wheels touching the ground,  remove the drift and use the rudder to align properly with the runway.

As you can imagine, it is more challenging simply because your heading and track are offset and you must quickly straighten the airplane at the proper moment.  When judging when to straighten the airplane out, it is better to do it too early than too late. It takes a bit of time for the airplane to be sufficiently affected by the drift to cause you serious problems. If you remove them too late, you will have a much bigger problem where you can cross load the landing gear, possibly damaging it, or worse.  Use wind aileron throughout the roll.

Crab landing in an airliner. Image courtesy of The Blaze.com.
Crab landing in an airliner. Image courtesy of The Blaze.com.

 

This photo is an example of a fairly extreme crosswind landing.  If the wind is causing this jet to crab so steeply, you can imagine that it is too strong and unsuitable for a smaller aircraft.

What about flaps?

Typically, it’s a good idea to always use flaps on approach, except in the case of a strong crosswind. The increased surface area of the wing just gives the crosswind more opportunity to blow you around, and when the crosswind is strong, don’t use flaps, or use less flaps in a moderate crosswind.

How about a crosswind takeoff?

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Stalls and angle of attack: a very important relationship

The relationship between stalls and airspeed is often misunderstood.   It is not actually the airspeed of the aircraft that will determine when the wing will stall, but rather the angle of attack.

Stall recognition is generally taught with reference to airspeed only.  Students are taught to pull up to stall the aircraft and continue doing so, watching the airspeed bleed off, watching the needle go from the green arc, through the white arc where this ends, and the airspeed at which that aircraft (in that particular configuration) is known to stall.  Instructors drill into us the importance of angle of attack, and that the aircraft can stall at almost any airspeed. In fact, my instructor and I stalled the aircraft at full power settings. It was surprising and intense, and very important to recognize that this can happen.

There is no instrument to show the relationship between angle of attack and airspeed determining stall due to the complex forces that determine when an aircraft will stall, including weight of aircraft, load factor, the aircraft’s center of gravity, and other factors such as altitude, temperature, aerofoil contamination (frost or ice on wings) and turbulence.   The airspeed indicator alone cannot measure when a stall will occour.

Your POH will give you stall speed with flaps up and flaps down configurations, for a certain weight. We learn in ground school that stall speed increases with weight forward center of gravity (which acts like an increase in aircraft weight), load factor (such as in a turn) and when there is surface contamination.  Once you know the basic stall speeds, it is up to you, the pilot, to be able to recognize when you are increasing or decreasing the stall speed.

It’s not the airspeed, it’s angle of attack

A typical lift curve, showing where lift angle is reached, which is about 16 degrees in this example. Image from wikipedia.org
A typical lift curve, showing where lift angle is reached, which is about 16 degrees in this example. Image from wikipedia.org

Angle of attack is the angle at which the relative airflow meets the wing. This is what determines when a wing will stall. It’s important to understand relative wind – this is the way the air flows over the wing – when this is disrupted, air can no longer flow the way it’s designed to over the wing, and lift decreases.  The critical angle of attack is reached when the maximum lift coefficient is obtained, after which lift will drop off when the angle is exceeded, and the aircraft will loose lift. After the critical angle of attack is reached, the aircraft is said to be approaching a stall.

The aircraft will always stall at the same angle of attack, called the critical angle. Many modern jets have an instrument that prevents the pilot from increasing the angle of attack past the critical angle, this is called the angle of attack limiter or alpha limiter.

Dangers of being low and slow

However this type of tool, or similar instrument is not in most general aviation planes. This leads to the pilot having to be very careful in making sure they don’t push their airplanes in into this flight envelope. When is a stall most dangerous? When you are low and slow.  Typically, the base to final turn can be very hazardous, and this is corroborated with the amount of stall-spin accidents that happen during this circuit sequence (for general aviation airplanes).  On this turn, you are low, and your airspeed is decreasing since you are on approach. When you turn, you increase the load on the aircraft, and if you push it into a stall (say, by executing a steep turn) you can enter a deadly stall-spin from which recovery is difficult due to the proximity of the ground.

ICON Aircraft GuageRecently I’ve discovered the aircraft manufacturer Icon Aircraft. This company has created an angle of attack instrument for general aviation airplanes.  This instrument measures angle of attack and presents it to the pilot showing when they are flying within the proper range.  This is a very interesting development that should go a long way into increasing safety.

I recommend watching the video about the concept below. Very cool!