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Pilot Perception: Runway Illusions

On Final

The “softer” side of flying is the human factors side. As advanced as modern aircraft are, pilots are subject to various factors that can cause them to make excellent decisions and judgement calls but sometimes make decisions that can be potentially dangerous. Luckily, illusions pilots experience are well understood and documented.  We know when we may experience an illusion.  In instrument flying for example, we learn how to ignore what our body is telling us – for example, that we are in a steeply banked turn when we are in fact in level flight – we learn how to trust our instruments in IMC.   Sometimes the message our body is telling us can put us in danger if we subscribed to it.

We are governed by the messages our body is sending to our brain.  This affects our flying and our perceptions of certain situations.  When we are approaching a runway with a up or down slope, or when we are approaching a runway that is level but the terrain before the runway is up or down sloping, it is possible and expected to incorrectly plan our approach.

Runway illusions are very common in flying, and are the result of our brain telling us something other than what is actually happening because it is extrapolating on what it sees.

Runway slope illusions. Image courtesy of americanflyers.net
Runway slope illusions. Image courtesy of americanflyers.net

When a runway is upsloping, the pilot thinks that the runway continues on an upslope from the terrain before it, hence thinking the terrain in front of the runway is upsloping as well.   The pilot will judge their altitude as too high, because they perceive the terrain continues on an upsloping, positive angle towards the runway  and will consequently plan a low approach that can cause landing short of the runway.

The solution? When flying toward a known upslope runway, expect that you will perceive being higher than you actually are and plan to land long on the runway.

When a runway is downsloping, the pilot thinks that they are too low and will consequently plan a higher approach and land long on the runway, or may even have to overshoot.   This is again, because of extrapolating on the slope of terrain before the runway.  Thinking that the terrain continues on a downslope towards the runway, means that the terrain is actually higher away from the runway than on the approach path; so that the entirety of the approach path follows downsloping terrain.  The pilot will incorrectly judge altitude as being too low when in fact he is too high.

The solution to planning an approach on a downsloping runway is to anticipate feeling like you are too low and plan to land short of the runway.

Also, when the runway is level but the terrain before the runway is upsloping: the pilot will extrapolate the same way.  They will think the runway is upsloping as well, and be subject to the same upslope illusion, and should plan to land long.  Alternatively, when the runway is level but the terrain before the runway is downsloping, the runway will also be judged as downsloping, and the pilot should plan to land short to avoid an overshoot.

It is hard to memorize the concept but I found that a good way of learning and remembering the concept is to draw an upsloping or downsloping runway and flat terrain in front of it. Then draw a straight dashed line following the angle of the runway towards the approach path, and this will be the pilots perception of the approach terrain.   From there we can easily imagine whether the pilot will feel too high or too low in each situation.

Rain on the windshield can create the the feeling of greater height and haze can make distances appear greater than they are. This is a favorite Transport Canada exam question as well!

Wide and Narrow Runway IIlusion
Wide and Narrow Runway Illusion

There is also the classic, wide and narrow runway illusions.  When a runway is narrow, this creates the illusion that the plane is higher than it actually is, resulting in a low approach and possible land short of the runway. With a wider runway, the opposite occurs, we perceive the plane lower than actual, and can cause the pilot to flare too high or overshoot the runway.

Writing a lot of exams lately, I noticed that Transport Canada likes to test these topics!

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Density and Pressure Altitude

Hot summer flying makes for low density altitude.

When we go flying, we always calculate pressure and density altitude of our aerodrome and for our cruising altitude. Why do we do this? Recall the definitions of density altitude (DA) and pressure altitude (PA).

PA is the “height above sea level corresponding to a given barometric pressure under standard air conditions” (FGU, page 41).  What are standard air conditions?  Standard air conditions state that at sea level, the air has a pressure of 29.92″ Hg and temperature of 15 degrees C.  As we increase in altitude, the air cools at the adiabatic lapse rate of 1.98 degrees per 1000 feet.  This allows us to calculate our altitude for pressure given the pressure reading at our aerodrome. To calculate this, we always subtract our current altimeter reading from standard pressure of 29,92,  multiply by 1000 then add it to the actual AGL elevation of the aerodrome.

For example, at Springbank, when the altimeter reading is 30.15:

29.92 – 30.15 = -0.23 * 1000 = – 230  then add to the altitude of CYBW which is 3940:  3940 + (-230) = 3710.   This means that the actual pressure, at standard atmospheric conditions, is lower than actual field height.

The reason we need to know pressure altitude is because our altimeter is a pressure altimeter.  It is important to set the altimeter because knowing the actual height of the airplane is of vital importance.  An altimeter setting that is too high will give an altimeter reading that is too high, a low setting will show a reading that is lower than we actually are.   Generally, most standard altimeters doesn’t go above a pressure reading higher than 31.0 0″ Hg. Such high pressure readings are found in very cold, dry air masses.   To correct for this, the pilot can add 100 feet for each 0.10 ” reading above this figure.  This will give the true altitude of the aircraft.

So why do we need to know pressure altitude anyway? When we do flight planning, we need to calculate it for our departing aerodrome not only to have the proper pressure setting for our altimeter, but also because the performance of the aircraft is based on pressure altitude.  These are more direct engine performance things, like fuel burn, true airspeed and engine thrust. We always look at our POH to find the true airspeed which we base on pressure altitude, like climb and cruise performance.

Hot, hazy summer day produces high density altitude and reduced performance
Hot, hazy summer day produces high density altitude and reduced performance

Density altitude is based on pressure altitude. It is simply pressure altitude corrected for temperature.   Once we calculate pressure altitude, we use the following formula:

DA = PA + [ 100 * (Actual Temperature – Standard Temperature) ]

Actual temperature is self explanatory, if we are looking for temperature of our aerodrome it will be given in ATIS or if we are looking for the temperature of our cruising altitude that is available in the Upper Wind Forecasts (FD’s).  To get  standard temperature recall the definition of standard air conditions: cools at the adiabatic lapse rate of 1.98 degrees per 1000 feet. So we can calculate this ourselves to know what the standard temperature should be at our chosen altitude.  For instance, for my last flight I flew at 6000 feet and the standard temperature at this altitude is (6 * 2 = )12 degrees less than 15 degrees, or 3 degrees.  We can also refer to our aircraft’s POH, where standard temperature for the pressure altitude is listed.

Density altitude is important to know for lift and aerodynamics.  Have you ever taken off from an airport on a hot, hazy summer day and noticed the decrease in engine performance?  On these days it takes longer to accelerate and become airborne because the air density is behaving as if it were in much higher altitude – where there is less air for the aircraft to “grab” onto.  DA is important for calculating safe fuel and payload permissible for takeoff.

High density altitude makes take off and climb take longer. Last summer, on 30 degree days when flying circuits I noticed that I was consistently not reaching circuit altitude until I was well into my downwind leg. Typically, I reach the altitude on crosswind.

What gives good performance?  Low altitude (higher air density), cold and dry. Bad performance? High altitude (lower air density), hot and humid.

Also read how altitude affects performance.

 

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Air law – definitions of Canadian airspace

Canadian Airspace. Image from IVAO.com

Following up on the previous article on air law, let’s review some details about Canadian airspace.

Air law is such a big topic and is very hard to cover in it’s entirety, so if you want more detail or more material refer to From the Ground Up and Canadian Aviation Regulations,  the Canadian Aeronatical Information Manual.

Canadian Domestic Airspace is divided into seven classification, each identified by a single letter.  The rules governing each airspace depend on it’s classification and not by which name the airspace is commonly known.  Control l or terminal areas can be classified B, C, D or E but weather minimums for flying are still related to the common name of the controlled or uncontrolled airspace.

The classification, as you may remember from ground school, looks sort of like an upside down layer cake, where the smallest classifications are nearer the ground and larger zones extend upward.

Class A 

This is all controlled high level airspace, only IFR flight is permitted. It spans from FL180 to FL600, inclusive.  ATC (air traffic control) is provided to all aircraft, and require clearance to enter.

Tower at YBW. Contol zones can be class B, C, D or E.
Tower at YBW. Contol zones can be class B, C, D or E.

Class B

In class B airspace, IFR and VFR traffic is allowed. ATC is provided. It includes all controlled low-level airspace between 12,500 and up to, but not including 18,000. VFR traffic must file a flight plan and request a route to enter.  A pressure altimeter is required (has to have been certified within 24 months) and a transponder with mode C capability.

Class C

IFR and VFR permitted. VFR must be cleared by ATC to enter. Terminal control areas and associated control zones may be classified Class C when the appropriate ATC unit is not in operation.  A 2 way radio and transponder with mode C capability is required.  In case of a communications failure, squawk 7600.  Otherwise,  VFR traffic must use 1200 on transponder.

Class D

Both IFR and VFR traffic are permitted, and VFR must establish radio communications with ATC.  ATC separation is only provided to IFR traffic.  Terminal control zones can be classified Class D, and if there is no ATC they will revert to Class E.

 Class E

This class of airspace exists when none of the requirements for neither A, B, C, D are met. Both IFR and VFR are permitted but again, ATC separation is only provided to IFR traffic. There are no special requirements for VFR traffic.  Low level airways, control area extensions, transition zones and control zones without an operating tower may fall into this category.

Class F

Forbidden or advisory airspace.

Class G

Does not fit into any of the other airspace categories, and ATC has neither the responsability nor obligation to manage traffic. This is uncontrolled airspace.  Low level air routes and aerodrome traffic zones fall into this category.

It’s easy to forget these classifications.  A useful mnemonic to remember these types of airspace and what is associated with each will help you remember!

A = Airliners. IFR only. Between 18,000 and 60,000 feet.

B= IFR.  Between 12,500 and 18,000

C = Clearance required to enter

D = Dialogue is required. Do not enter before talking to a controller.

EEasy for VFR, Everyone gets home from this class of airspace, no need to talk to controllers.

F = Forbidden, or Fancy  – special use airspace.

G = General uncontrolled airspace.

And of course, the U.S. has their own unique system of classification.  Information on the U.S. system can be found in From the Ground Up.

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Pilot stuff for girls – Review of Powder Puff Pilot Products

Even though there are a lot of girl pilots at my school, where I would say at least one quarter of students are women and there are lots of female flight instructors, aviation still is very male dominated.   I was ready to buy a headset, which my instructor encouraged me to do so sooner rather than later.  Buying a headset should be your first purchase as a pilot, and it is your most important purchase.

Flying with my pink ANR headset from Powder Puff Pilot.
Flying with my pink ANR headset from Powder Puff Pilot.

Your ears are very important and you have to take steps to protect your hearing – small propeller driven planes are very loud and over time exposure to these loud noises can damage your hearing. As well, you need to be comfortable and not strain your hearing when talking to your instructor, ATC, or other pilots.

I found an ad for a store that sells pilot stuff for girls, and I was impressed by the uniqueness of the concept.  When I saw a headset that was pink, and even though I’m a complete tomboy I liked the idea of having something “girly” in the male-dominated flying world.  So I went for it. The headset is actually very good quality, which was my number one criteria. The fact that it was girly was an added bonus.

The headsets come with two options, either passive noise reduction (PNR) or active noise reduction (ANR).  The PNR only reduces noise using the insulated gel cups while the ANR actually uses attenuation to actively reduce noise, and requires a battery. I chose the ANR model for maximum noise reduction.

I am very happy with the products I’ve purchased and whenever I have had an issue, they have excellent service and get back to me right away. They stand behind their products.

Flight bag and seat cushion
Flight bag and seat cushion

They also sell lots of other gear, such as flight bags, clothing, accessories, watches and they also have a seat cushion which is my absolute favorite item.  I check back regularly to see if anything new is added. My seat cushion gets a lot of comments! It is bright pink, memory foam and very comfortable.  It has two non-slip strips on one side so it doesn’t slide around in the airplane seat.

My current instructor (a guy!) teases me to no end about my girly pilot gear. Is some of the stuff is cheesy? Maybe. Cute? Definitely.  Check them out, great gifts for female aviators, aspiring aviators, and young aviators.

These products are available for purchase in our store.

 

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Headset Review – Powder Puff Pilot

The new ANR Headset is MP3 compatible.

My first purchase as a flight student was a headset. This is quite unarguably your most important purchase, and should be your first and done as soon as you start flying (and can afford it).  Headsets can be purchased for as little as $100 and go up in price according to quality.  The range is about $100 – over $1000. As you can see it is quite a huge price spread. This is an important first purchase – you need to protect your ears while flying and most flight schools offer rental headsets that just don’t fit right, are abused or neglected – and you need something good quality that is your own, so you can take care of it and will serve you well.  They are your ears, so deciding how much to spend is really up to you.  I suggest spending a bit more and getting something better quality and that fits properly.

When I started flying, I found an ad for “Powder Puff Pilot”, a company that makes pilot gear for girls, and purchased their noise attenuating (ANR) headset, and have been using it for years. This was my first headset, and my first purchase as a flight student.

Recently, I received the latest ANR headset from them and there have been some nice improvements.  First, the headset is now MP3 compatible, meaning you can insert a headphone jack into the unit to either listen to music or talk on your phone while in flight!  It is a neat feature and very convenient, and I can’t wait to try it on my cross country flight, where I might have a little more time than I do now, zooming in and out of the practice area or in the circuit.

On final approach, wearing the headset.
On final approach, wearing the headset.

ANR or PNR?

The headsets come with two options, either passive noise reduction (PNR) or active noise reduction (ANR).  The PNR only reduces noise using the insulated gel cups while the ANR actually uses attenuation to actively reduce noise, and requires a battery. I chose the ANR model for maximum noise reduction. The ANR reduces noise attenuation by 20 decibels.

In the ANR model, a tiny microphone in the ear cup picks up noise around it, and this noise “sample” is converted into a mirror opposite of the sound – which is silence. ANR only affects certain low frequencies, so speech aircraft sound, engine sounds and changes are all easily detected.  PNR models only block out noise using the physical clamping of headset on the wearer – squeezing tight to physically block out any noise.   Because of this, they tend to be heavier and bulkier than ANR headsets.

The pink headset from Powder Puff Pilot comes in both ANR and PNR models.  The ANR model comes with a battery pack that takes two AA batteries. When the batteries aren’t inserted (or die) the unit functions as a PNR headset.  The ANR model is priced at $335 and the PNR at $210.

Highly recommend the headset.  Along with the MP3 compatibility, the headset also has thick gel pads on the ears, meaning even without the battery there is good noise cancellation. The headset fits smaller than most and is good for women. The headsets come with a 1 year warranty. The warranty at Powder Puff is excellent and they stand behind their products.

Headsets are available for purchase from our store.

What is your favorite headset?

 

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What is VFR?

IFR Flying Conditions. Image Courtesy of Langley Flying School.

It’s springtime, and out here in Alberta the weather is all over the place. From clear, sunny, calm days arrive strong wings, snow, sleet, rain, low ceilings and all sorts of weather, signifying change of seasons. Yesterday for example we did not have VFR weather here.  In fact, with a visibility of 1/2 SM, vertical visibility of 500 feet and snow at CYBW we have LIFR, or low instrument flight rules conditions – this means ceilings and visibility conditions below IFR minimums. Ceiling is below 500 feet and visibility is less than 1 SM.

There are two kinds of flight rules, visual flight rules and instrument flight rules.  VFR stands for visual flight rules and means the pilot flies the aircraft with visual reference to the ground, using landmarks, roads, avoid aircraft in the vicinity, avoiding terrain and obstacles.  The pilot must know where they are at all times and maintain visual contact with the ground at all times.

Weather minimums have been established to allow the pilot to fly VFR.  These are listed in the table below:

VFR Weather minimum. Image from the AIM and Langley Flying School.
VFR Weather minimum. Image from the AIM and Langley Flying School.

As long as these minimums are observed, the pilot can fly VFR.  Remember that some types of airspace do not allow VFR traffic, or VFR traffic must seek permission in order to enter certain kinds of airspace.

Also applying to VFR traffic are altitude rules. VFR traffic flying at 3000 feet AGL or higher must follow specified rules about altitude depending on direction flown. Cruise altitude is based on magnetic track. The altitudes are:

For headings: 000 degrees – 179 degrees = ODD thousand + 500 feet

For headings: 180 degrees – 359 degrees = EVEN thousand + 500 feet

VFR traffic is not allowed to fly over cities (built up areas) lower than 1000 AGL, and should not descend below 500 feet AGL during flight – of course this does not apply to special flights (police, ambulance) nor during take off or landing phases of flight. This explains why the traffic helicopter always seems to buzz my house!

VFR traffic can use instruments to operate, but are not allowed to rely on them unless they have an IFR rating, and are flying IFR.

Pilots flying VFR are allowed to start a flight that is initially VFR but changing to instrument meteorological conditions (IMC), and where visual flying will not be encountered anymore.  The best thing to do in this situation as a VFR pilot is to either fly straight and level until the conditions improve, or complete a 180 degree turn where you came from to return to visual conditions. Also, if you are near a control zone, you can request SVFR – special VFR.  The aerodrome must have at least 1 mile visibilty and you must remain clear of cloud.

If you are not near a control zone and encounter these conditions, you are forced to fly IFR.  The best solution is to avoid IMC if possible unless you are IFR rated.

Another solution is to fly VFR “over the top” or OTT.   This is a special rating that private pilot license holders can get to fly over cloud cover, maintain visual contact with other airplanes flying IFR while giving VFR pilots greater flexibility. This rating can be added to your PPL with 15 hours of  flight training.