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What is Field Elevation?

One of our readers asks “What Is The Field Elevation printed on Airport Diagram and why is it important?”

The Field Elevation on the Airport Diagram references the Airport Elevation. The Federal Aviation Administration(FAA) defines the Airport Elevation as the highest point of an airport’s usable runways and is measured in height above mean sea level. Much of aviation symbology and regulations have changed to match the standards set forth by the International Civil Aviation Organization (ICAO). Therefore on VFR charts you will also see the definition of airport elevation as the highest point on the usable portion of the landing areas.

Why the importance of airport elevation?

To provide for terrain clearance and compliance with speed restrictions you will need to know the field elevation. For example the maximum speed allowed within 4 nautical miles or five statute miles of the primary airport of class C airspace is two hundred knots up to two thousand five hundred feet above the primary airport elevation. So if you want to fly fast over the primary airport in Class C airspace you must know the airport elevation to avoid a speeding ticket, translated a violation. Another reason you must know the hight above the airport elevation is to comply with minimum visibility requirements. So as you can see knowing the airport elevation is important.

Examples:

View the excerpt of the airport diagram for Tampa International Airport depicted above. The box at the end of runway with the notation “Field Elevation 26” This depicts the highest point on the runway which also coincides with the Touch Down Zone Elevation (TDZE) runway 28. If you look at runway 10 there is a depiction ELEV 14 which is the Runway End or Touchdown Zone Elevation of runway 10. The Touchdown Zone Elevation is the highest elevation in the first 3,000 feet of the landing surface.

The field elevation is not always located at the end of the runway. Look at the airport diagram for Trenton airport depicted below. The field elevation is depicted at the intersection of taxiway A and runway 16. Since this is within 3,000 feet of the end of the runway, the touchdown zone elevation is the same as the field elevation which is 213.

Many of us enjoy flying out of grass strips and know that many have large dips and rises in the runway. If you look at an airport with a grass runway the airport elevation is the highest point of all these dips and rises in the runway. No offense to owners of level grass strips. I really appreciate you.

Conclusion:

Airport Elevation figure depicted on the airport diagram is the same as depicted on the sectional and instrument charts. The airport elevation is based on a specific point along the usable portion f the landing area. Most of us only view the field elevation and its impacts on us as pilots during and oral exam for a rating or a job. The practical use of this figure is for complying with speed and visibility restrictions at airports.


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For more than a decade I have been helping people realize their aviation dreams and goals, one of which is to become an airline pilot. I have watched many achieve success by fulfilling the dream of piloting a sophisticated jet around the world. The one thing that amazes me is how many people don't understand the hiring cycles of the airlines and how to prepare for the next hiring boom.

The lack of understanding of the airline industry amongst both the general public and the pilot population became clear to me after September 11, 2001. After the tragic events that day and the subsequent downturn in the economy I decided to get involved in assisting furloughed pilots find jobs and advance their careers. I have seen many pilots soar to new heights in their careers and other careers crash and burn.

There are two important factors in becoming a successful airline pilot, airmanship and experience. Airmanship is the is ability to skillfully fly the aircraft. Experience comes from hours of flying in various environments. If you are going to become an airline pilot you should continually increase your flying skills and your experience.

Experience

When airlines hire they normally publish a minimum number of flight hours. If you don’t have the minimum hours most airlines won't even look at your qualifications no matter how good a pilot you are. Even if you feel you have enough experience to get hired you should continue to build your flight time. You also need to be building the type of flight time the airlines want which is multi-engine time.

There are many programs in this country which help pilots build multi-engine flight time in a very short period of time. I suggest your looking into one of these if you wish to put your piloting career into high gear. I have seen many pilots go from no flight time to the right seat of an airliner within six months simply by building all of their time in a twin.

The minimum flight time airlines require is based on the number of pilots available for hire. If there is a large supply of pilots the required hours both published and required increases. The airlines publish a number of hours which can normally be found on their website. This number is simply a minimum number which will allow you to apply. However, the number many times not published are the hours required to be competitive. .

Many pilots set their hourly goals too low. The first goal most pilots set is to meet the minimums and then apply to the airline of choice. After some pilots reach this hourly minimum, some make the mistake of slowing down and some even stop flying. This is not a good idea. You should never stop trying to build your flight time because similar to the wind the number of hours required to get a job will constantly change. I remember when I first began flying the joke was that in order to get on with a major airline you needed "perfect eyes, perfect tan, ten thousand hours, and two moon landing". With some airlines this wasn't far from the truth, but what many didn't expect is that only a decade later major airlines would hire pilots with as little as five hundred hours. Again the supply of experienced pilots diminished to the point the airlines could not find experienced pilots willing to apply. This will happen again.

The Hiring Cycle

Advancement at an airline is based solely on seniority which is why the sooner you are hired the faster you move up the seniority list. It is a difficult concept to understand for those not in the industry. Just remember there are no lateral moves in the airline industry so you need to expedite your hire date. For example, if Sully Sullenberger was hired at Delta Airlines today he would be the most junior pilot at Delta.

The reason airlines need more pilots is twofold. First, the airline is expanding and is flying more. There is a finite number of hours a pilot can legally fly, therefore they must hire more pilots to cover their schedules.

The second reason airlines hire is that they are losing pilots. Because of the seniority system at the airlines most pilots don't ever leave until they retire or lose their medical.
Airline Pilots are mandated to retire at age sixty-five and a small number retire early. A simple method to determine how senior you will become at an airline is to look at the number of pilots at the airline younger than you and that will be your estimate maximum seniority not factoring in early retirements and medical retirements.

Similar to all businesses, airline hiring is cyclic. Most furlough during bad economic times and hire during good times. Since the airlines hire in cycles you will see groups of pilots hired within a very short period of time. You also will see many pilots retiring at the same time. This is why you should look at the age of the pilots on the seniority list to determine in what years there will be a great number or retirements.

Regardless of retirements you should always be prepared for the next hiring cycle by gaining as much experience and increasing your airmanship. I wish I had a dollar for every pilot who quit flying and then started flying again when things started picking up. Many missed two separate hiring cycles and are still trying to break into the industry.

Airmanship

You should always strive to be the best pilot you can be with a goal of being both a competent and safe pilot. Airmanship is the ability to both control the aircraft and make sound decisions while operating in the aeronautical environment. Different flight operations require various skill sets but all can be categorized as Airmanship. Someone flying in the wild arctic tundra of Alaska must have good stick and rudder skills while someone who flies in low visibility and constantly in the clouds must have good instrument skills.

Airline pilots must operate in all weather conditions and must be able to land an airplane in very high and gusty winds. An airline pilot must also fly in very low visibility and with precise control of the aircraft with reference to the instruments. If you are planning on becoming an airline pilot you should be a well rounded pilot and able to fly in both strong crosswinds and low visibility.

During the hiring process the airline assumes you can fly to commercial pilot standards. The airline will train you to competently fly the aircraft they are training you on but you must come with the basic skills to fly an airplane especially with regard to instrument flying. Therefore if you are building hours but have not flown an instrument approach in months you need to get your skills up to par.

If you are making your living flying banners you need to get into a good simulator or get some instrument time before going to an interview or to training. One of the deficiencies I have seen many pilots terminated for in the past is their inability to control the airplane with reference to the flight instruments.

Normally the lack of basic instrument skills is made evident during the training process and your chances are high of dropping out if you can't get your instrument scan back up to standard. During times of intense hiring the airlines occasionally make exceptions. It is my experience that pilots who lack basic instrument skills will be trained by the airlines only during times of large pilot shortages. With that said I would not bet my career on the fact the airline you get hired with will be kind enough to train you to fly by reference to instruments. You should arrive instrument current and competent.

Furthermore, If you have been furloughed with an airline and have been recalled it would be best for you to get some instrument time either in the plane or by using one of the many outstanding simulators. You will increase your confidence, skill, and knowledge of instrument procedures.

In my experience every time I have seen pilots recalled from furlough, a few obstinate pilots feel the airline should train them to be a proficient pilot when they are recalled to work. Nothing can be further from the truth. Luckily most airlines will allow you to reapply after being terminated due to lack of flying skills. I suggest you don't get yourself into this situation.

You should always keep flying but if you find there is an area you need to work on you should do it before showing up for an interview or for training. I suggest your getting your instrument instructor certificate and teach. One of the best ways to master something is to teach.

Exceptions To The Rule

There are exceptions to all rules and getting hired with an airline has many. You will notice that during times when there is an overabundance of pilots some will get hired with as few as five hundred hours. Almost as important as what you know is who you know. Being involved with internships are a great way to get yourself in the door at the chief pilots office and increase your chances of getting hired.

Conclusion

There is always a coming pilot shortage due to the cyclic nature of the airline business and retirements. To prepare for the upcoming shortages you should gain as much time and experience right now. There is never a substitute for airmanship but equally important is increasing your flight time. Both of these will make many jobs available to you when the hiring door opens. You want to be the first in the door when the hiring cycle begins because it will some day shut again. Remember with the airlines everything is dependent upon your seniority and the faster you get in the door the better.

Keep Flying!


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Wouldn’t it be great to observe an instrument flight and listen to pilot and controller interactions on a daily basis? You would become better at communicating and understanding the nuances of operating from various types of airports.

One way to get this experience is to watch Sporty’s IFR Communications video which brings you into the cockpit during a variety of instrument flights. Not only will you get to ride along and listen to the communications between the controller and the pilot you will also hear commentary by the experts at Sporty’s explaining the meaning of the last communication.

Video Thanks To ThePilotReport.com

My favorite aspect of this video and the reason I recommend it to my students is that it gives examples of operating in and out of many different types of airports. If you primarily operate out of tower controlled airports and you are apprehensive about your next trip departing a non towered field you should watch this video.

The instructors at Sporty’s clearly explain methods of obtaining your IFR clearance at non towered airports. You then will get in the cockpit and follow along as the pilot obtains his clearance and then flies to his destination. During the process the instructor interjects explanations and standard procedures including organizing your cockpit and the recommended sequences of preparing for the flight.

This video includes three separate flights with various avionics panels. One flight is in a Cessna Skyhawk with a VOR and no GPS. For those who only use the VOR for backup this is a great opportunity to review position determination by cross radial. Furthermore, it will show you how to communicate with controllers who are accustomed to people flying with avionics allowing direct to navigation. When was the last time you needed vectors to join and airway or an intersection?

A second flight is in a G1000 equipped Skylane. The first part includes a review of the glass panel and pertinent features. I particularly enjoyed this because I am becoming acquainted with the G1000 and learned some good operating tips from this video.

The third flight is in a classic Piper Aztec into the busy New York Airspace using GPS and a multi function display, MFD. You will navigate busy airspace and see real life examples of multiple reroutes in flight with a landing at LaGuardia airport. If you ever wondered how to make a reservation at a busy metropolitan airport, this is the perfect primer.

The Video Includes:

  • IFR Communications Review
  • Emergency Lost Communications Review
  • Obtaining your clearance at non towered airports
  • How and when to cancel your IFR flight plan
  • When it is a good idea to pick up your IFR clearance in the air and when you would not want to.
  • Learn when you should cancel in the air before you land and when it can lead you into a trap.
  • How to work with Air Traffic Control to get the outcomes you want.

Conclusion:

I recommend Sporty’s IFR communications for all experience levels of instrument pilot. The DVD includes examples of operating in a wide range of flight environments. For those who rarely operate in one of these environments, such as the busy New York Airspace, this would be good review prior to planning your flight. The instructors are very good and the use of graphics and inflight video make this a pleasure to watch.

An added benefit to viewing this video is that you can earn FAA Wings credit online by taking an exam afterwards. Thus placing you one step closer to earning your wings and your flight review. I used this video for credit towards the Wings program after taking the online exam associated with the video.

At $31.95 this DVD is a bargain especially if you compare it to the cost of flight and ground instruction. I would highly recommend Sporty’s IFR Communications for all my instruments students and instrument rated clients.

For More Information:

Wings Credit

Sporty’s IFR Communications DVD

Sponsor:


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On Monday April 18th a Boeing 737 carrying the First Lady was required to discontinue their approach to Andrews Air Force Base because they came too close to a C-17. For those of us who fly often we know air traffic control may accidentally bring us too close to a larger plane in front of us and we must execute a go around, but when the First Lady is on board it makes the news. All the media attention to this event gives us a perfect opportunity to review the concept of wake turbulence and the regulations and procedures we should use to avoid an encounter with the wake of a large aircraft.

What is Wake Turbulence?

During flight the air pressure above the wing is less than the air pressure below the wing. Since air flows from low to higher pressure the air below the wing will try to flow upwards along the path of least resistance. Since the fuselage blocks the flow, the path of least resistance is towards the wingtips. The air on top of the wing tends to flow slightly towards the fuselage where a vortex is also generated but because of the fuselage disrupting the flow this vortex is insignificant.

Now we have air curling up over the wing tips and flow from the top of the wing downward called down wash. The two combine at the wingtip and create a fast spinning vortex similar to horizontal tornadoes trailing the aircraft. You can see these vortices in person if you sit at the end of a runway and watch a very large aircraft land. Many times you will see the vortex bend towards the ground setting up mini tornadoes sucking up dirt and debris as the vortex travels along the ground.

The vortex or wake from an aircraft is only produced when the airplane is creating lift and increases as the wings angle of attack is higher. As a review the angle of attack is the angle between the wing cord line and the relative wind which is opposite the flight path. The greater the angle of attack the greater the pressure differential between the bottom and top of the wing. The largest wake an aircraft will produce is when an aircraft's angle of attack is highest which is when the aircraft is heavy, clean, or slow.

Vortex Behavior

The trailing vortex of an aircraft is not usually visible making them hard to avoid if you don’t know the behavior of an aircraft’s wake after the plane passes through a section or air. To help you avoid the wake of a large aircraft there are some tools we can use based on the action of the wake.

The wake of an aircraft begins from the moment the wing produces lift. Therefore from the moment the plane begins to rotate until the plane lands and the weight of the aircraft is transferred to the wheels there is a vortex being produced.

The vortex of the aircraft trails behind the aircraft and is slightly less than the wingspan of the aircraft. The vortex will normally move downward at rates of two hundred to three hundred feet per minute. Away from the surface the vortex will be influenced and travel with the wind normally stopping between five hundred to one thousand feet below the aircraft.

Within one hundred to two hundred feet above the ground the vortex will move down and outward traveling sideways or laterally along the ground at approximately two to three knots. The vortices near the ground are also subject to influence from the wind. The most dangerous situation is a tailwind from the left or right side of the runway because the vortex tends to stay over the runway.

Wake Turbulence Avoidance

The best way to avoid the wake of a preceding aircraft is to stay well behind and above the wake. To do this we must visualize where the wake is and where we should position our aircraft to avoid the wake.

Landing

When landing behind an aircraft on the same runway stay at or above the approach path of the preceding aircraft touching down beyond the preceding aircraft’s touchdown point.

When landing behind a heavy aircraft on a parallel runway closer than two thousand five hundred feet anticipate the vortex drifting onto the runway you are using. Again try to land beyond the touchdown point of the aircraft on the parallel runway.

When landing behind a heavier aircraft landing on a crossing runway stay above and land beyond the path of the heavy aircraft.

When landing behind a heavy aircraft departing on an intersecting runway rotate before the preceding aircraft’s rotation point. If the heavier aircraft rotates prior to the intersection of the runway you are landing on then go around.


Departing

When departing behind a heavier aircraft on the same runway rotate prior to the heavy aircrafts rotation point and climb above the heavy airplane’s flight path. This might require a turn after takeoff.

If departing after a heavier aircraft did a low approach, touch and go, or a go around wait at least two minutes before departing. The vortices will descend below the flight path and will also move laterally if the plane was within two hundred feet of the ground. The vortices may stay over the runway especially in a light quartering tailwind. The best action would be to wait two minutes before departure.

Even if you fly out of an airport with small planes the airport close to you might handle large jet traffic. This is the case in the airport I fly out of which is on the same approach and departure path as an Air Force Base. I have a friend who was approaching our small airport when he was rolled by a large military transport aircraft flying across his path. Luckily he was a aerobatic pilot and took this in stride and just rolled with the vortex and recovered.

Enroute

While enroute avoid being below and behind a larger aircraft. The best avoidance if you find your self below a larger aircraft’s wake is to move laterally, preferably upwind from the aircraft’s path.

Air Traffic Control Procedures and Wake Turbulence.

While landing or taking off visually behind a heavy aircraft or a Boeing 757 you will be issued the cautionary advisory “caution wake turbulence” followed by the position, altitude and direction of flight.

If you are directly behind and aircraft in a radar environment Air Traffic Control will give you certain minimum separation standards. Any aircraft within two thousand five hundred feet of the flight path of another aircraft is considered behind another aircraft. Using this standard, aircraft operating on runways less than two thousand five hundred feet apart will be treated as if landing on the same runway and be considered behind the preceding aircraft.

Separation standards while under radar control vary based on the size of the aircraft you are following and the size of your aircraft. Aircraft are classified into three categories based on weight. A heavy aircraft is one that weighs 300,000 pounds or more. A large aircraft is one that weights more than 41,000 pounds but less then three hundred thousand. A small aircraft is any aircraft forty one thousand pounds or less.

  • A heavy behind a heavy requires 4 miles separation.
  • Since the wake of a 757 is so great a large or heavy aircraft behind a 757 must be separated by 4 miles.
  • A small aircraft behind a 757 must have 5 miles separation.
  • A small or large aircraft behind a heavy aircraft must have 5 miles separation.


  • The FAA has interim procedures for aircraft following the Airbus 380. Aircraft flying behind an A380 will be separated by 6 miles for a heavy aircraft, 8 miles for a large aircraft , and 10 miles for a small aircraft.

    If the following aircraft comes within this distance the air traffic controller will separate them by changing the direction of the following aircraft or in the case of a landing aircraft make the plane go around. An example of this occurring is when the plane carrying the First Lady was issued a clearance by air traffic control to discontinue the approach because they came within the separation standards of the preceding heavy C17.

    Wake Turbulence Avoidance Is Everyone's Responsibility

    Air traffic control does a great job of keeping us safe while we are flying in the clouds but they are human and make mistakes. That is why it is important to try to listen to not only the clearances given to you by ATC but also to listen to other aircraft on the radio. This will increase your awareness of the situation tremendously.

    If you see the aircraft in front of you and tell ATC that you have the preceding aircraft in sight they will issue you a caution “wake turbulence” but you are on your own in providing separation from the preceding aircraft's wake. If you do get too close to the proceeding aircraft, Air Traffic Control should issue you a caution and the distance from the proceeding heavier aircraft. If they tell you to abandon the approach and go around you should immediately begin your missed approach or go around.

    It is important to realize that although it is everyone's’ responsibility to avoid wake turbulence the pilot is responsible for and is the final authority to the operation of the aircraft. Positioning yourself away from the wake of the aircraft in front of your aircraft may at times be the responsibility of ATC but ultimately the pilot in command must decide if you are at a safe distance and altitude.

    Safe Flying!

    For More Information:

    NTSB releases new details on Obama flight incident


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    It was a great day to practice some touch and goes since the winds were blowing and my friend, we will call him Jim, needed some crosswind practice. Jim and I fly out of Peter O. Knight Airport in Tampa Florida which is only a few miles from MacDill Air Force Base, home to some important military commands. We often see the military transport aircraft flying overhead, and occasionally with some very important people. These VIPs, especially the Joint Chiefs Of Staff will cause a Temporary Flight Restriction, TFR and today was one of those days where we had a TFR right over the airport.

    Jim left work early to do some local flying from Peter O. Knight. Taxing to the runway Jim saw one plane depart and another plane call with their intentions of departing. After listening to the weather Jim switched back to the CTAF and announced his intentions of crossing a runway on his way out to depart.

    This is when he heard someone calling his N number on the CTAF. He answered and it turned out to be the local FBO trying to contact him. The FBO asked if he knew about the TFR because of the Vice President’s visit? Jim said no, but then thanked him and taxied back to the hangar.

    After putting the plane away, Jim drove to the terminal building to thank the manager for warning him about the TFR. Unfortunately, two planes had just taken off and the US Secret Service were looking for those two planes because they needed to talk to them. One of them always flies IFR but departs VFR and picks up his clearance in the air, but today this was not a good idea. Looks like two pilots had a very bad day.

    I hope you never violate a TFR because it usually comes with a minimum ninety day suspension of your pilot certificate. Let me give you some tools that will help you in avoiding violating an TFR.

    What is a TFR?

    A Temporary Flight Restriction is a Flight Data Center (FDC) Notice To Airmen (NOTAM) which is issued for a variety of reasons including:

  • Protect persons and property in the air or on the surface from an existing or imminent hazard.
  • Provide a safe environment for the operation of disaster relief aircraft.
  • Prevent an unsafe congestion of sightseeing aircraft above an incident or event which may generate a high degree of public interest.
  • Protect the President, Vice President, or other public figures.
  • Provide a safe environment for space agency operations.
  • The majority of TFR’s require a pilot to be on an Instrument flight plan, therefore shutting down most VFR operations. This is one reason many look towards getting their instrument rating, especially if they operate in an area with many TFR’s. Although as you will see having an instrument rating does not always keep you out of trouble.

    How To Avoid Violating A TFR

    Since the terrorist attacks on the United States TFR’s are common and they can be implemented at the last minute. Some of you have decided to stop flying recreationally since it might jeopardize your professional pilot job. Some have decided to not fly at all recreationally when a TFR is implemented because most TFRs require you to be on an IFR clearance and you don’t want to get your instrument rating or you are not instrument current.

    Over the past decade there have been numerous violations involving VFR aircraft flying into TFRs so I understand pilots reticence in taking off when one is near. Rest assured there is a solution to the high number of TFR violations. First, know the TFR exists and second know the boundaries of the TFR.

    How To Find TFR Information

    TFR’s can easily be found but take some action on your part. In rare instances a TFR may suddenly appear and become affective while you are in flight. Some have invested in GPS displays which depict the current TFR’s and will normally catch these TFR’s that may occasionally pop up. But the most important thing to do is to become acquainted with all available information including TFR’s

    Before I fly I look up the TFR’s on the FAA’s website at www.tfr.faa.gov . This is a great start to your preflight because this website has listed most TFR’s, although a disclaimer exists at the bottom of the website warning that this website is only for planning purposes. You should always contact a briefer prior to your taking off on a VFR flight to determine if any TFR’s exist. To obtain the TFR’s along your route of flight check the FDC NOTAMS. Right before you leave it is always a good idea to receive an updated briefing to check if any TFR’s have suddenly popped up, especially if you operate near an area prone to VIP visits such as MacDill Air Force Base.

    Filing IFR doesn’t always keep us clear of TFR’s.

    Many flying Visually tend to stay on the ground when TFR restrictions are in place because we don’t want the added work of talking to air traffic control and getting a clearance. Those that fly for business will many times file and fly under Instrument Flight Rules, which most of us feel will keep us clear of all TFRs. But things don’t always go as planned and there are a few instances where you can still get into trouble.

    The majority of my professional flying is out of cities where I obtain my clearance for ground control or clearance delivery. For my personal flying I choose non towered airports primarily because after talking to ATC all week I like the freedom and peace and quite of a silent radio when departing a sleepy little airport. When I do fly cross country I almost always file IFR to keep me away from TFR’s and for the added safety of always being in contact with ATC.

    The two airports I do my pleasure flying from both have a remote communications outlet where I can pick up a clearance before departing. Most of the time when I call clearance and it is VFR they will ask If I can depart VFR and pick up the clearance in the air. So that is what I usually do. I take off and ask for my IFR clearance airborne.

    In the case above this would not have kept me clear of the TFR since the flight restriction included the airspace above the airport. In this case filing IFR would not have kept me clear of a TFR violation since I would have taken off into the airspace unknowingly had I not checked the NOTAMs.

    Many times while enroute on an IFR flight plan we become tempted to cancel in the air since the airport may be in sight many miles away and we don’t want additional vectoring from Air Traffic Control. Canceling in the air is many times more convenient than calling ATC or Flight Service on the ground. The only caveat is you must make sure you are not going to violate any TFR’s especially if you are very far away from the airport. To keep myself out of trouble I normally don’t cancel until I am on final or on the downwind and know I am well clear of any potential TFR’s

    Conclusion:

    Avoiding TFR’s is more difficult since the terrorist attacks on the United States. The best avoidance is to use all tools available and to talk to a briefer just prior to your departure. One of the best ways to avoid a TFR violation is to file and fly under instrument flight rules if you have the rating. Some pilots I speak with get their instrument rating for the primary purpose of being able to fly through TFR’s.

    There are many tools at your disposal in trying to avoid a call from the Secret Service for violating a TFR. Using the FAA website, filing IFR, and calling flight service before you depart are all ways to dramatically reduce the risk of violating a TFR. Always be vigilant and remember a short call to flight service to get information on TFR’s takes much less time than an enforcement hearing with the FAA.

    Safe Flying!

    For More Information:

    FAA TFR Website http://www.tfr.faa.gov

    Sponsor:

    Thanks to David Sorg for his question concerning how to avoid violating TFR's.


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    Compass Errors : Is More Than 10 Degrees Legal?

    A reader asks "I know the airplane must have a magnetic compass but I heard the compass error cannot be more than ten degrees”. My friend flies a plane with more than a ten degree error. Is this legal? Also how is the compass tested and how often is it checked?

    Requirements

    The compass is an instrument which often is ignored in modern technically advanced aircraft, but it is one of the most important instruments in our airplane. A magnetic direction indicator is required in all aircraft with a standard airworthiness certificate, see Title 14 Code of Federal Regulations Part 91.205 Besides being required by law, how else would we be able to determine our direction if all of that advanced equipment fails in flight.

    Deviation

    All magnets are prone to errors due to magnetic flux generated when the electrical equipment in the airplane is turned on. This error is called deviation error. Many of us fly airplanes with a vertical compass card which is less prone to oscillations in flight but is still prone to the same magnetic errors.

    Compass Correction Card and Swinging The Compass

    To compensate for the magnetic errors produced by the electrical equipment in the aircraft a compass correction card is installed in the aircraft. The compass correction card shows every 30 degrees of heading and a box underneath with a value filled in by the mechanic when they "swung the compass".

    Most airports have a compass rose with cardinal headings painted on the surface. The Aviation Maintenance Technician, AMT, will carefully taxi the airplane onto the compass rose and align the airplane with each of the cardinal headings. The AMT will note the heading on the magnetic compass indication and if there is an error try to adjust the compensating magnets to remove any errors

    More than ten degrees of error

    Any errors the AMT cannot remove must be noted on the compass correction card which is placed on or near the magnetic compass. It is a common misunderstanding that a compass cannot have more than ten degrees of error because the regulations in part 23.1327 state the "compensated instillation must not have more than ten degrees of error in level flight".

    If you continue to read the regulation the last sentence allows for "deviations of a magnetic non stabilized direction indicator of more than 10 degrees" but the deviations must be placarded and in compliance with part 23.1547(e). The regulation says the placard must state which electrical loads, or combination of loads, would cause a deviation of more than 10 degrees when turned on.

    When Must We Swing The Compass?

    Advisory Circular AC 43.13-1B contains practices and repair methods. The Advisory Circular states the AMT must swing the compass for the following reasons:

    (1) When the accuracy of the compass is suspected.

    (2) After any cockpit modification or major replacement involving ferrous metal.

    (3) Whenever a compass has been subjected to a shock; for example, after a hard landing or turbulence.

    (4) After aircraft has passed through a severe electrical storm.

    (5) After lighting strike.

    (6) Whenever a change is made to the electrical system.

    (7) Whenever a change of cargo is likely to affect the compass.

    (8) When an aircraft operation is changed to a different geographic location with a major change in magnetic deviation. (e.g., from Miami, Florida to Fairbanks, Alaska.)

    (9) After aircraft has been parked on one heading for over a year.

    (10) When flux valves are replaced.

    The only problem I have with this advisory circular is their example of a compass being subjected to a "shock". Their example of a "hard landing" is subjective. Just make sure an airworthiness inspector is not within ear shot when you comment "boy that was a hard landing". You might be required to swing the compass afterwards. Seriously though if it has been a bouncy day, either weather or pilot induced, and you notice your compass is not reading accurately you should talk to a mechanic because it might be time to swing the compass.

    Conclusion

    The magnetic compass is often overlooked because the electronics in our new technically advanced aircraft will give us a more accurate heading indication without much thought process. A magnetic compass, especially the old “whiskey” compass requires some knowledge and training in proper usage. When was the last time you did compass turns? Maybe it is time to practice and become proficient using the magnetic compass again.

    During your review of the compass you might find on one heading there is more than a ten degree heading error which might be cause for alarm. You may remember hearing from your instructor “There can be no more than a ten degree error so you can’t fly.” As you now understand this is not the case as long as the error over ten degrees has been noted and placarded.

    The placard must indicate the specific electronic equipment operating when the error was noted. Normally the placard will include two lines, one with the compass error with all the radio equipment on and one without the radios on. This will assist you in steering when you have a complete electrical failure and have turned all of your radios off.

    Multiple electronic heading indicating systems result in our rarely using the magnetic compass except for aligning the heading indicator during preflight and readjustment during cross country flights. If you have an electronic heading and attitude referencing system you may only check your heading displayed on the electronic display before flight and ignore the compass the remainder of the flight.

    Although rare, all of your electronic systems can fail and the only remaining heading instrument is your magnetic compass. It happened to my coworker recently. To stay proficient take notice of the movement of the magnetic compass during turns and accelerated flight. Try to anticipate what the compass will do while you maneuver the aircraft. If you have any questions regarding the use of the compass find a flight instructor and have them show you its proper use. This will make you a safer and more proficient pilot especially when your electronic or gyroscopically stabilized heading indicator fails.

    Safe Flying!

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    I could see the frustration on my student's face. She really wanted to make better landings but seemed to have reached a plateau in her progress. I could empathize with her because I was a student and remember having the same experience.

    While taxiing back to the runway after a bounced landing but a good recovery I started thinking how I could encourage her. It was a silent cockpit and the air seemed thick as oil. One thing I have learned over the years is pilots are more critical of their own landings than of others and I am sure she was thinking that was the worst landing in the history of flight.

    The plane rolled to a stop in the middle of the long taxiway as she gently pressed the brakes. Not saying a word at first she looked in all directions to make sure no other planes were in the way and then looked at me in desperation and said "Do you think I will ever be able to make good landings?"

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    Sometimes the most difficult decisions we make are on the ground especially when taxiing on an airport with many intersecting runways. One airport I notice I must pay more attention to while taxiing is Louisville Airport (KSDF).

    One day while leaving we were given instructions to taxi to Runway 35R via Delta cross Runway 29. We crossed 29 and began approaching the end of 35. As we approached the runway we noticed bright flashing yellow lights in the pavement and two alternating yellow lights on either side of the runway.

    Getting closer we noticed a taxiway marking with two solid yellow lines and two dashed yellow lines furthest from us. Next to the taxiway is a sign with a red background and white lettering that says 35R-APPCH. I turned to my coworker and said I'm going to hold short. I said this as conformation with him and after we stopped I explained to him that even thought we briefed the taxi, in my mind I was expecting to see an ILS critical area sign which we see often.

    I saw the approach hold line on the diagram before I began my taxi to the runway but in my mind I pictured an ILS critical area and was in the mode of continuing my taxi to the end as I normally would unless given instructions to hold short of the critical area. Since the yellow Wig-Wag lights were illuminated and the yellow pavement mounted lights were flashing, it brought to our attention the holding line so we held short. What would you have done?

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    Expect Holding; Now What?

    Approaching Houston we were issued the clearance "turn right heading 320 maintain seven thousand expect TRANN". Without further instructions what do we do next if we lose communications?

    If you lose communications you must comply with FAR 91.185 which states if we lose communications and we cannot continue in visual conditions we must fly to the fix we were told to expect in the clearance. While being radar vectored the controller should tell you what to expect next in case you lose communications. In our case the controller issued instructions to expect TRANN intersection. Therefore, we should fly direct to TRANN if we lose communications.

    But what if we are given the clearance "descend to seven thousand turn right direct TRANN expect holding"? Afterwards the the Air Traffic Controller gets busy giving instructions to other airplanes. Now what do we do?
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    Why Learn To Fly?

    DSC_0007Reclining on the wooden bench on this humid morning, I watched the cool mist slowly dissipate. The only noise was the dew dripping from the hangar. The thin fog covering the grass seemed like a silk bed sheet covering the sleeping grass below. I took a deep relaxing breath noticing the smell of fresh cut grass. The only movement was from small birds and an occasional dear grazing, lulling me into a catatonic state.

    My peaceful respite was suddenly interrupted by a grinding noise followed by an explosive burst from the small airplane. The engine rattling to life caused a rush of excitement and adrenaline through my body. I sat upright in anticipation of watching a small plane take to the air.

    It was my senior year of college and I should have been studying for my finals but I couldn't help but come out to the airport and view the magical and mysterious event of an airplane leaving the ground and flying through the air.

    A short burst of noise emanated from the small engine and the propeller began moving very fast. The plane shook for a moment and suddenly jerked forward. The engine noise then became silent and the airplane rolled, moving gracefully as it made its way toward the runway.
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