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Understand how to use VOR and ADF Nav aids to orient yourself anytime

VOR cessna 172 flytime

Nav aids like the VOR and ADF are there for you to use anytime you should need them. Having a solid understanding of these navigational (nav) aids is important and goes beyond training offered to us as private pilots, but is available for us to learn to become proficient aviators, particularly if we are regularly flying long distances, with passengers, at night, or any combination of those.

Basic nav instruments can be valuable

In a typical aircraft used for flight training, usually a Cessna 172, we’ll often have a VOR, ADF and GPS.  When we’re training for our private license, we typically aren’t introduced to these tools, but we do learn about them briefly in ground school. In commercial training, we learn about all of these in more detail and must become proficient at them, as we’re expected to demonstrate their use on a flight test. But it should go beyond that. Even if you’re not training for a commercial license, you should be familiar with these nav aids and how to use them. In case the weather should deteriorate, particularly at night, you’ll be much safer.

These basic instruments can help you create a situational ‘mental map’ of your location, a mental map that will become invaluable should you get lost or encounter adverse weather and are forced to divert. 

Preparing for a worst case scenario

Having the simple, yet valuable information provided by these basic instruments becomes extremely important in case the worst should happen. What if you take off with a shaky forecast, and fly into some weather? We’ve all been told that if we head into clouds or low visibility we should note our heading and begin a 180 degree turn into the reciprocal heading.  But how about if we just loose visibility, flying into an area of low cloud or haze? We need somewhere to go, so how do we find it? We have to find a suitable place to divert to, and knowing where your ADF and VOR stations are on the map can help us get there. 

A flight instructor gave me instructions for a simulator session to use as training in these instruments. The exercise has many practical applications for flying in both day and night, as it helps orient you in reference to a station and an airport, to help get you land when you need to terminate your flight due to deteriorating weather. It’s better to try to land at an airport than planning a landing in a field

The VOR

The VOR transmits 360 single radials from a specific station. When you select a specific radial on your VOR instrument, you’ll be able to see which side of the VOR station you are depending if you see a “TO” or “FROM” flag.  For example, say you are lost somewhere in the vicinity of Springbank airport in Alberta, and you want to return to there and land. You’re not sure which way you should head to get back to your airport. Knowing the frequency for the Springbank VOR, you tune it and immediately you’ll be able to get information of which side of the station you are on and how you should track to get back there. 

Where am I?

Here is an example.

Once you tune your VOR to a station, select radial 150.

If it says TO, that means you’re on the other side of that radial. If it says FROM, you are on that side of the radial. 

The ADF

Your automatic direction finder, or ADF is a basic instrument that transmits location information on the AM band. To use, tune it to a non-directional beacon (or NDB). The arrow on the ADF will always point to the station. 

ADF flytime alicja gados
The ADF on a Cessna 172. The ADF always points to the station.

These stations will eventually be shut down in Canada, and Transport Canada has been planning to decommission the stations for years. This planned decommissioning is not happening quickly. They still remain, and will likely be around for years to come, and while they do, are a basic, though valuable navigational tool that you can use to orient yourself. 

Where am I?

To use, once you tune the ADF to the specific NDB frequency, listen for the morse code. That is how you know you have the right NDB. Now, note where the arrow points. 

The arrow always points to the station. To head directly to the station, align the nose of the airplane at the top of the instrument (0 degrees). To depart with the station directly behind you, align the arrow to point directly behind the airplane. 

A real life example

You depart Calgary/Springbank on a VFR flight with paying passengers heading north to Rocky Mountain House. The GFA shows a cold front moving through the area from the northwest with deteriorating ceilings and visibility over the next six hours.

On your way out to climb runway heading of 350 to 5500′, you intercept and track outbound of the Turner Valley NDB (299) and continue the climb to 6500′. 

From Calgary International, you can track the V306 airway (116.7) to track outbound (away from) Calgary towards your destination. On your way along the track, you can tune to the Sundre NDB and to track your progress also and report when you’re abeam the station (when you are passing the station on your left hand side). 

So, you know where you are and continue en route.

The ceiling drops. Now you have to descend to stay VFR. You descend to 4500′, taking note that there are towers in the area that are close to that altitude. Tune the Red Deer NDB (320), and use it to keep track of when you pass the James River, not abandoning the flight quite yet.

The weather gets worse  – it now becomes unsafe to continue, and no longer VFR.  Now you abandon your original course and aim for the closest airport – that is Red Deer. You’ve already got the NDB tuned to Red Deer, so you just turn and track direct to there, climbing back up to 5500′.

Enroute to Red Deer, you experience a vacuum failure. This means you’ve lost your heading indicator and attitude indicator, and you’re now flying partial panel, using your turn and bank coordinator as the best indicator of your attitude, cross referencing the airspeed and VSI to confirm. 

You’ll cross the Red Deer NDB at your altitude of 5500′ and begin a descending, rate one, right turn to get to runway heading of 345 (the runway you’re aiming for will be runway 35). This is a timed turn, so you’ll have to note your heading going into the turn and make sure your turn is consistently rate one throughout. Or else you may over or undershoot your runway, and you don’t want to spend any more time flying around in precarious weather with limited instruments. 

Once you land safely, there is great reason to celebrate. You have just used your skill to get your passengers, yourself, and your airplane down on the ground safely.

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Rated turns: the two minute turn

right seat approach cessna

What is a rated turn?

A rated turn is a two minute turn as indicated by the turn and bank coordinator. It’s very useful in instrument flying. When the turn and bank indicator is coordinated in a rate one turn, it will take 2 minutes to travel 360 degrees. By knowing this information we can use it to get us to a heading that we want. 

turn coordinator from the ground up
The turn coordinator. Image taken from the From the Ground Up textbook.

The turn coordinator shows a coordinated rate one turn when the wing tips of the miniture airplane touch the lower bands, either right or left depending on the direction of turn, and the ball is in the center. For example, if the wing touches the right tab and the ball is in the middle, if you keep it like this for two minutes you’ll end up on the same heading you started. If you keep it like this for one minute, you’ll end up 180 degrees to the right: in the exact opposite heading on which you started. 

This instrument has plenty of practical applications particularly when you are lost or have lost visibility, to help you roll out on certain headings. 

Understanding it is important for both the private and commercial flight tests.

Application

Rated turns are important in limited panel flying to get yourself into an airport and out of sketchy IMC conditions.

For example, you’ve tracked an NDB to a known airport, and now you need to descend to below the cloud base to land at the airport. You are planning to land on runway 35 so you know you need the heading of 350 degrees. Currently you’re on a heading of 050 degrees. Using our turn and bank indicator, we can plan a properly coordinated, descending rate one turn to bring us out of limited visibility and into visual sight of the airport runway. 

Use available tools to calculate

Remember that a timed turn is a two minute (120 second) turn that takes you 360 degrees.  This means if you’re turning 360 degrees / 120 seconds you’re turning 3 degrees per second. To do the math, make it simple for yourself and count the dashes on your ADF or heading indicator. This will help you minimize workload. It will help avoid getting confused by random arithmetic problems, and allow you to focus on keeping your scan going and flying the airplane safely, your number one priority. 

The ADF is marked every 30 degrees: the scale shows 0, 030, 060, 090 and so on. Each of these 30 degree marks is 10 seconds (at 3 degrees per second). So look at the heading you are on and the one you want to go to, and count the seconds in these 30 degree increments.  

ADF instrument in a cessna 172
The Automatic Direction Finder (ADF) in a Cessna 172.

In this case we want to fly from 050 to 350, so we count 90 seconds from 060 to 330. Add another 10 seconds to account for the extra 30 degrees from 050 to 060 and 330 to 350. This means it will take us 100 seconds or 1 minute and 40 seconds in a coordinated rate one turn. Set up your descent and start your turn, and begin your timer.

Once you reach 100 seconds, you should roll out on 350, or close to it. By then you should be able to see the ground and the runway. 

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Instrument flying: flying with a partial panel

cockpit 1957 beechcraft airplane

The complexity of  flying on instruments increases when we simulate a vacuum failure. We loose one especially critical instrument necessary to our flight attitude coordination. The Loss of this instrument in flight can certainly and very quickly and easily turn into a life and death situation.

The purpose of partial panel training

The goal of partial panel simulation is simple: what would happen if you were to have a vacuum failure in the most critical time, when you were in IMC or flying at night? The reason for learning essential basics of instrument flying, including emergencies such as partial panel, doesn’t have to be so complicated as to just needing it to earn your IFR rating for airline flying. 

How the vacuum system works

The vacuum system is operated by a venturi which is usually engine driven. The change from higher to lower pressure drives the gyros, so these require some time to spool up and are only accurate after takeoff.  

The heading indicator and attitude indicator are vacuum system powered gyros and the turn and bank indicator are electrically powered. So in the event of a vacuum failure, you’ll be able to use your turn and bank indicator to assess when you are wings level and coordinated.

How can we end up with a partial panel in real life flying?

Since in airline flying you’d never encounter this situation, you can experience a vacuum failure at the worst possible as a private or bush pilot, or a pilot for a smaller operation that does bush flying in remote areas. There can be pressure to complete a job, pick up passengers, or get people to a certain destination. You know the weather is going to deteriorate but you decide to go anyway. You fly into the front which has come earlier than forecast and end up in a situation where you are pushing the weather.

Deteriorating weather

Picture you’re on a night cross country flight with little to no great reference to the ground. You’re essentially flying on instruments. Or, you’ve departed during day VFR with a sketchy forecast, and you’ve inevitably flown into an area with low ceilings and decreasing visibility. It starts slowly at first, and before you know it, you can’t see the ground, and you don’t know which way is up.  If the worst was to happen and your vacuum system loses suction at this time. You’ll be in deep, trying to keep the airplane under control while trying to figure out what the heck you need to do to get yourself out of this situation.

The first thing you do, of course, is be prepared for this type of worst case scenario by practicing these difficult situations under the hood or better yet, in the simulator. You can even practice at home. Have your instructor create a scenario for you where you are flying to an area with a less-than-ideal forecast tracking different VOR radials and NDBs, and along the way simulate slowly diminishing visibility until you are forced to divert. Enroute to your diversion aerodrome you loose your vacuum system, and are forced to fly without your AI and HI. You need to get to your airport and out of this mess. 

Cessna 182 in northern alberta
Cessna 182 stuck at a snowy airfield in Northern Alberta.

1. Don’t panic – fly the airplane

The first thing you do if this happens to you is to remain calm, and fly the airplane. Remember to always aviate, navigate and then communicate, in that order. Always focus on flying the airplane before you do anything else. This is especially true when you’ve found yourself in a low visibility situation with limited instruments. 

Focus on the instruments that give you the information you need, and start your scan. In the case of full panel flying, this is a lot simpler because you have your attitude indicator at the center of your scan which gives you your most critical information: the position of your airplane against the horizon. Are you nose up or nose down, and are your wings level or are you in a turn?

Start your scan

When you lose your vacuum system, your gyros, the heading indicator and attitude indicator will be immediately unreliable. The major challenge with this is that these two instruments, particularly the attitude indicator, are at the center of our scan. So we have to quickly develop a new method. 

The main concept continues unchanged, you continue to control the aircraft with the formula attitude plus power equals performance.  The difference is now you have to look at other instruments to get this information. When flying without an attitude indicator, you must determine your pitch by primarily referencing your airspeed indicator, and verifying it with altitude and vertical speed indications. 

Control Instruments

Attitude: Airspeed Indicator

Referencing your airspeed indicator for pitch is challenging but doable and requires significant practice to master. My instructor set up a scenario in the sim where my vacuum system failed in cloud while on a low-level diversion to Red Deer. I flew this route a few times and found it took a few minutes to organize the scan before I got the aircraft into a reasonable state of control. The important thing is not to chase the instruments. I did this at first, and found my airspeed all over the place, and then my altitude started to fluctuate and I descended to only 500 AGL. 

This happened because I was not allowing the airspeed to stabilize. A certain attitude will give you a certain airspeed. Let it stabilize and reference your altitude and VSI to ensure you’re at a stable straight and level attitude. 

Turn information: Turn and Bank Coordinator

Use the turn and bank coordinator to verify that you are wings level. Use the magnetic compass to verify the heading has not changed. Do not fly heading via the magnetic compass, it’s too confusing. The compass works in the opposite direction to turn. So unlike a heading indicator, you turn away from the heading you want to go to, the opposite response that makes sense. The compass also has a significant amount of lag. It’s only reliable to verify that we are on the proper heading, but not looking to it as a control instrument. 

Your performance instruments

The performance instruments help you verify the impact of your control inputs are or aren’t what you want them to be. In partial panel flying, they are always attitude plus power equals performance:

Attitude + Power = Performance

Control Instruments + Power = Performance

Airspeed Indicator + RPM = Outcomes shown on the VSI, Altimeter and Magnetic Compass

Turn and Bank Coordinator + RPM = Outcomes shown on the VSI, Altimeter and Magnetic Compass

2. Navigate 

Find out where you are by using VORs, NDBs, GPS or ideally combination of those. You can also ask for vectors. This of course bring us to:

3. Communicate

Let air traffic control know you’re in an emergency and ask for help.

Next find out how to use rated turns to get yourself out of cloud and into an airport. Executing a timed turn is a critical skill and becomes very important during partial panel flying.

 

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Simplify Flying: it’s attitude plus power equals performance

I’ve had the pleasure of flying with a retired airline pilot who really made me think about flying in an entirely different way. His view demystifies flying into it’s basic, component parts to understand a complex task and achieve a certain goal. Attitude plus power equals performance.

He maintains that after over 20 years of airline flying, he found there are two very important concepts in flying airplanes. Once these concepts are understood, will help you understand aviation and flying at it’s core. The most important concepts in aviation are ones we have all heard before, and it’s impossible not to overstate their importance. They are:

  1. Aviate, Navigate Communicate; and
  2. Attitude plus Power equals Performance.

Think about what flight training is trying to achieve. Yes, you are trying to pass your flight test, at a minimum, but you can certainly do better than that. You can be a great pilot. Why practice stalls and spins? To avoid entry, to recognize if one should occour, and how to recover. 

Let’s relate it to a few examples. 

Once our wheels are off the ground, we are in a ‘risky environment’ where it’s important to keep vigilant.  When we are airborne, our one and only task is no minimize the risk, using all of our knowledge and resources. So break it down into what you have to achieve once you’re wheels up.

Remember clearing turns? We do them so we can be safe and check for conflicting traffic, and not just because they are a flight test item. Risk mitigation is also why we have standardized procedures for uncontrolled aerodromes.

On takeoff, after rotation, the airplane is just passing through a very slow speed at a low altitude. On the 172 we rotate at 55 knots, so after we rotate it’s close enough to stall speed to warrant extreme attention, particularly given our proximity to the ground. When you rotate, will you pull the nose up excessively? No, of course not, you can easily enter a stall that way, a departure stall, and you won’t have the leisure of altitude to recover.

So when we depart, we use the combination of attitude and power to produce the desired performance that we want: a climb. When we recover from a stall is it necessary to push the nose down excessively? Not really, and if you think about what stall practice is meant to achieve, we really should avoid pushing the nose down too much.  If it works on a take-off, it should work on stall recovery. If we push the nose down too much, we’ll loose altitude, and if we stall close to the ground that can be dangerous.

The purpose of stall practice

Stalls are a great case in point. Stall recovery has no practical application in everyday flight like short field, soft field landings, navigation, circuits and so on. We only learn them so we can avoid them, learn to recognize when we are in one, and know how to get out of them. Licensed pilots who don’t fly professionally will find stall recovery skills atrophy after awhile, because unless flight training, stalls are something we want to avoid. 

What produces a stall? A high nose attitude where the angle of attack of our airplane can no longer sustain flight. Your attitude is nose high, the airplane will automatically drop the nose because it wants to fly.  A nose down attitude will break the stall, and the application of power will allow you to return to a normal flight attitude. Attitude plus power equals performance. Aviate: break the stall, return to normal flight, navigate: establish where you are; communicate: this includes communicate with your airplane. Why did it stall?  

How about the forced approach?

The forced approach is a good example. With an engine failure, we’ve got to: (1) aviate: establish the best glide speed, establish a controlled approach and landing; (2) navigate by deciding which is the best field to land our airplane at; and (3) communicate, make a mayday call on 121.5 and give our passengers, if any, a full off-airport emergency safety landing briefing.  For the forced approach, we use best glide speed, a combination of attitude and power (in this case, lack of power), that produces a level of performance: the descending glide.

cessna 172 lake view
cessna 172 lake view

A heap of metal

Remember the airplane is just a “thing.”

The airplane is not alive. Many things on the flight test and flying itself can cause confusion, and above all, anxiety, which can take the fun out of flying. When learning to calm anxieties, it’s helpful to think about the airplane having no feelings or malicious intent. It’s just a heap of metal that you control and has no goal or agenda of it’s own. It’s simply a tool, a tool that you, the pilot, control.  You are flying the airplane and the airplane is not flying you.

A blend of two important factors, attitude and power, will produce the environment that we can control. Like a car, the airplane is a predictable thing. When given certain parameters it will always do the same thing. Nose up? Airspeed will decrease. Nose down? Airspeed will increase. No power? It will enter a descent. Full power? It will climb. Winds will push the airplane in known directions, crosswinds will have a known effect on approach paths, and so on. 

It’s all well within our control.

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Uncontrolled airport procedures

There are a very large number of uncontrolled aerodromes in Canada where no control tower operates. Also, some controlled aerodromes are uncontrolled at certain hours, if tower closes. For example the CFS may indicate the control tower is closed from 0000 to 0600 daily, so you’ll have to follow uncontrolled procedures during that time period. If you’re not being directed by air traffic control (ATC), you’ll need to know how to plan your approach. It’s important to think of the approach procedure in advance, visualizing it before you go.  Make sure you do this. Try visualizing using “chair flying” at home before you head out.   

At some uncontrolled aerodromes with an appreciable amount of traffic, Transport Canada may assign a Mandatory Frequency (MF) or Aerodrome Traffic Frequency (ATF) that you must use. Make sure you have these frequencies ready when you plan to land at one of these uncontrolled airports. When an MF or ATF is designated, it applies to an area with about a 5 NM radius, so when you’re in that radius, make sure you’re active and listening on that frequency. Also, it’s illegal to operate NORDO (with no radio) in an area with an ATF or MF.  I’m not sure why someone would want to fly without a radio anyhow, it sort of makes me nervous! 

Unless otherwise indicated, assume all circuits are left-hand and plan for those accordingly.

How to plan your approach

First, you must exchange communication through one of these frequencies, ATF or MF if applicable, if not, a Flight Service Station (FSS) or through the Universal Communications frequency (UNICOM). You’ll need to check your Canada Flight Supplement (CFS) and Aeronautical Information Manual (AIM) for current requirements. 

You’ll need to make five radio calls:

  1. Report 5 minutes out your location, approach procedure, and estimated time over the field;
  2. Report when crossing midfield (this is done 500 feet over circuit altitude, generally 1500 AGL). This is to inspect the runway to ensure it’s suitable for landing and do a wind sock check to choose the appropriate runway direction. This is know what type of landing you need to plan, and try to have as much headwind as possible, or if you need to plan a cross wind landing;
  3. Report when joining downwind leg;
  4. On final,
  5. Then lastly, report when clear of active runway after landing.

This image, from Transport Canada, outlines it nicely: 

Circuit procedures for uncontrolled airspace
Circuit procedures for uncontrolled airspace

 

Also see VFR procedures at uncontrolled airports diagram by Transport Canada, it’s very helpful. 

Departure procedures

Departure procedures are simple. You’ll also need to broadcast your intentions, of course, and climb to circuit altitude, typically 1000′ AGL, before making any turns. 

Did you know?

CARS, Canadian Aviation Regulations state you’re not allowed to overfly an aerodrome less than 2000 feet above that aerodrome. Just something to note when planning cross country flights. 

I fly out of a very busy airport, Springbank (CYBW), near Calgary, which is usually number 6 or 7 busiest in Canada for aircraft movements. To fly out of Springbank, you’ll need to talk to ground, inner tower, outer tower, then Calgary Terminal, before being cleared enroute. So, flying into a much quieter uncontrolled aerodrome is strangely quiet, and takes some getting used to. 

Do you prefer towered or non-towered airports, and why? Comment below.

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How does Centre of Gravity affect your airplanes performance?

When you complete your weight and balance form every time before you fly, you need to make sure it fits into your weight and balance envelope. We’re all used to doing it, so it’s second nature by the time we’re licensed, flying for fun, or continuing our training. We’ve all been through this in ground school, but it’s important to refresh the knowledge and remember how exactly airplane performance and handling are affected as to where your airplane’s centre of gravity lies. 

Forward vs. Aft Centre of Gravity

Your airplane is designed with a certain centre of gravity and a small allowance within which it is acceptable to move it. By moving the C of G location, you are changing the amount of downward tail force and lift of your airplane. When lift is created, so is drag, and this causes a decrease in performance.  The airplane needs to be within the envelope to properly handle and retain tested stall characteristics.

What is balance?

Balancing an airplane is a lot like balancing a teeter-totter. For the aircraft to be properly balanced, the sum of all the moments to the left and right of the pivot point (or fulcrum) must be equal.  The fulcrum of the airplane is located at the centre of pressure – or Centre of Lift on the wing. 

weight and balance pilottraining.ca
The centre of lift and fulcum of your airplane, showing C of G limits. Image from pilottraining.ca.

The load on the left is the total weight of the aircraft located at the C of G which is balanced on the right by the elevators. So what if the C of G changes? The elevator force must also change. So must it change if the centre of lift (centre of pressure) changes.

Every aircraft has a certain maximum forward and rearward C of G limit. This is inherent in the airplanes initial design. 

Aircraft moment causes your nose to pitch down, the tail down force causes moment in the opposite direction, balancing the airplane. The tail is essentially an upside down wing that generates downward lift. The amount of lift needed depends on two factors, the location of C of G, and the weight of the airplane. 

Effects of tail heavy CG

When the C of G is rearward, elevators must produce less downward force to maintain level flight, so the aircraft will fly more nose low.  

The effects of this are poor longitudinal stability, reduced capacity to recover from stalls and spins,  and creates a situation where very light control forces and make it easier for the pilot to over stress the aircraft with smaller deflections. It also causes an increase in cruise speed. 

These effects stem from less tail pressure on the stabilizer. Stall recovery will be difficult, and in some cases impossible, because of less tail pressure. Have you ever noticed that you’re not allowed to have passengers is some small airplanes when practicing stalls and spins? The extra rearward C of G causes the airplane to be out of the utility category, which is required for stall and spin practice. The Cessna 172’s we train on are like that. A rearward C of G changes the flight characteristics enough to make upset recovery difficult.

Effects of nose heavy CG

When the C of G forward, this causes the airplane to nose down, and a higher angle of attack will be required to balance out the forces. The elevator, which is in the aft end provides a counter balancing force to the nose down attitude. 

The airplane will need nose up trim, will be more stable and will cruise slower.  This is because there is more pressure and drag from the stabilizer. 

Overloading

Since we’re talking about how to put weight in the airplane, take note to why overloading an airplane is not recommended under any circumstance.  An airplane that is overloaded is dangerous. A decrease in performance will be one problem you will see, especially initially, but also you’ll have to deal with:

  • higher speed needed for take off
  • longer distance required for take off
  • reduced rate of climb
  • decreased range of flight
  • lower cruising speed
  • reduced maneuverability of aircraft
  • higher stalling speed
  • higher approach and landing speed will be required
  • and a longer landing roll and stopping distance.

You may have seen dramatization in movies of what airplanes can do, often with great exaggeration.  If you’ve seen American Made, starring Tom Cruise, you’ll note the scene where the pilot is coerced to take off from a high altitude, hot, humid dirt strip in the jungle, oh and did I mention it’s also a short field “runway” with high jungle on both sides, and the airplane is overloaded? If you study aviation, you’ll know that this is a bit of a ridiculous scenario, and when the pilot (Cruise) barely makes it over the trees, clipping the tops of the large trees, he averted disaster, but the scene is incredibly exaggerated and completely unrealistic.  High altitude with obstacles (such as trees or mountains) makes take off very dangerous.