Monday, 9 July 2018

PRE-FLIGHT WEATHER ANALYSIS CHECKLISTS – VFR FLIGHT


(Ed. Note: Apologies to my source, which on this occasion I failed to record! However, the advice received belowshould be taken on board by all!)

Ceiling and Visibility

·      How much airspace do I have between the reported or forecast ceilings and the terrain along my route of flight? Does this information suggest any need to change my planned altitude?

·      If I have to fly lower to remain clear of clouds, will terrain be a factor?

·      How much ground clearance will I have?

·      Do I have reliable ceiling information?

·      Will I be over mountainous terrain or near large bodies of water where the weather can change rapidly, or where there may not be a nearby weather reporting station?

·      What visibility can I expect for each phase of flight? (take-off, en-route, landing)

·      Given the speed of the aircraft, expected light conditions, terrain, and ceilings, are the reported and forecast visibility conditions sufficient for this trip?

·      Are there conditions that could reduce visibility during the planned flight? 

·      (Hint: look for indications such as a small and/or decreasing temperature & dew point spread).

·      Are reported and forecast ceiling & visibility values above my personal minimums?

Aircraft Performance

·     Given temperature, altitude, 
density altitude, and aircraft loading, what is the expectedaircraft performance in respect of?
·   Take-off distance
·   Time & distance to climb
·   Cruise performance
·   Landing distance

·       Are these performance values sufficient for the runways to be used and the terrain to be crossed on this flight? 
*(Note:Remember that it is always good practice to add a 50% to 100% safety margin to the “book  Numbers” you derive from the charts in the aircraft’s approved flight manual (AFM)

Turbulence

·    Are the wind conditions at the departure and destination airports within the gust and  crosswind capabilities of both pilot and aircraft
* (Note: For most GA pilots, personal minimums in this category might be for a maximum gust of 5 knots and maximum crosswind component 5 knots below the maximum demonstrated crosswind component.)

·    What is the manoeuvring speed (VA) for this aircraft at the expected weight?
*(Note: Remember that VA  is lower if you are flying at less than maximum gross weight.)

FLY SAFE!









Thursday, 5 July 2018

WEATHER WISDOM

Acknowledgements: Susan Parson (FAA SAFETY BRIEFINGJULY/AUGUST 2010)

(Ed. Note: A rerun of wisdom from Susan concerning the relationship between humans and the weather ….. after all, in a “fight” there is often only one winner…… )

“One of the oldest aviation clich├ęs holds that a pilot certificate or ratingis primarily alicense to learn. Nowhere is that saying more appropriate than it is for the newly rated instrument pilot. Like many pilots, I was eager to exercise my new privileges by getting the wings wet almost before the ink on my temporary certificate dried. Having passed the instrument rating practical test, I was confident of my ability to operate in the system, to shoot approaches, and even to enter and fly holding patterns. I had mastered the art of the scan and the rhythm of cross-check, interpret, and control. My knowledge of instrument flight rules (IFR) and procedures was solid. 

As I quickly learned though, my understanding of weather — specifically, how to think about weather in terms of a given flight — was as patchy as the clouds I so proudly passed through on my first IFR flight. The gaps in my knowledge became crystal clear on a very cloudy day a few months later when I launched into rapidly deteriorating weather that eventually forced a diversion and an instrument approach to near minimums. 

I’m not proud of the “go” decision I made that day, but the experience does have a silver lining. As you might imagine, it provided powerful motivationto become a dedicated and lifelong student of aviation weather. Eventually, it also led to discovering a simple but very effective framework for deciding whither and whether to fly in weather of all kinds. 

It is important to get a detailed weather briefing and I was always very dutiful about obtaining and printing out weather information from Flight Service (FSS) or one of the online direct user access terminal (DUAT) providers. Even more critical, however, is knowing how to pullthe most important pieces of information from piles of printer paper and apply them to the flight you’re about to make. 

Easier said than done. There was a time when I stared at those faithfully acquired weather printouts with the same expression of earnest confusion my Cocker Spaniel displayed when I tried to explain the importance of a bath. She didn’t get that picture any more clearly than I got the flick on weather. The Spaniel never did understand the bath rationale, but the light-bulb moment for my understanding of aviation weather came courtesy
of a simple concept in Robert Buck’s Weather Flying book. As Buck explains, there are just three ways that weather affects an aviator: 
1.    Weather can create wind
2.    Weather can reduce ceiling and visibility
3.    Weather can affect aircraft performance

Eureka!With this framework, I began to notice that data in aviation meteorological reports (METAR) and terminal aerodrome forecasts (TAF) is structured to provide information on each of these three weather conditions. I finally had not only the tools needed to mine the most critical pieces of information from the printout, but also the foundation for evaluating a specific day’s weather in terms of both the specific pilot — me — and the specific airplane I planned to fly. 

When the Wind Blows 
In both METARs and TAFs, the first item provides information on an airport’s wind direction and velocity. A key to wise weather decision making is to consider these numbers in relation to both the pilot and the plane. 
·      With respect to the pilot, the primary issue is proficiency and comfort with a known or forecast crosswind. If you are not comfortable with the crosswind component at the departureairport, it’s a good day to stay on the ground or, better yet, hire a qualified instructor to help scrub the rust off your crosswind take-off, approach, and landing skills. If it is the crosswind at the destinationairport that gives you pause, the next step in the windy weather decision-making process is to determine whether the winds are more favourable at alternateairports within range. When crosswind comfort is an issue at either end of the flight, it also pays to check wind at airports along your routein the event that diversion becomes necessary.
·      Regarding the airplane, the primary issue is its maximum demonstrated crosswind component, which is usually in the range of 12-17 knots for light GA aircraft. Though it is not a legal limitation, a GA pilot is wise to regard this value as a personal limitation. Here’s why. Aircraft manufacturers develop aircraft performance data through rigorous flight tests. These activities are conducted by professional test pilots who are, as the phrase goes, “simulating average pilot skills.” However hard we try, non-commercial GA pilots still may not obtain the aircraft performance that a professional who is “simulating” an average pilot’s skill level can achieve. 

Also, even if the true maximum crosswind component is higher than the published (demonstrated) value, there is inevitably a point at which full deflection of a given airplane’s rudder, in combination with aileron input, will not be sufficient to correct for the drift resulting from a stiff crosswind. Pilots refer to this condition as “running out of rudder.” I speak from experience when I report that it does get your attention. That particular teachable moment came for me on a gusty autumn day when I was first learning to fly from the right seat of a Cessna 150. Even with the right rudder pedal jammed all the way to the floorboard, the trusty little trainer was no match for the crosswind at that particular airport. 

BOTTOM LINE: Regardless of pilot proficiency in crosswind flying, it is also critical to consider whether the airplane is up to the challenge. A crosswind that is perfectly manageable in the beefy twin-engine Piper Aztec may well be too much for a tiny two-seat trainer. 

Flying Blind 
The next component of METAR and TAF reports ceiling and visibility, conditions that are the primary reason for learning to fly by reference to instruments. For legal instrument flying, an aircraft must be properly equipped and certified for IFR. Since, regardless of equipment the airplane itself is not affected by the presence of clouds and precipitation, weather decision making in this area most logically focuses on the pilot

For legal operation in instrument meteorological conditions (IMC), a pilot must be both instrument rated and instrument current. For safe operation though, the pilot must also be proficient in basic attitude flying, instrument operating rules and procedures, course intercepts and tracking, holding, approaches, and all other aspects of instrument flying.

The existence of the currency requirement bespeaks the perishable nature of instrument flying skills. As many pilots have discovered though, maintaining just the legal minimum requirement for currency may not be enough for proficiency and confidence. If you haven’t flown in IMC recently, or if you have any doubts about your proficiency level, you need to get some practice with a safety pilot, or some dual instrument-refresher training with a qualified instrument instructor.

Let’s assume you are rated, current, and proficient. Is that enough? Another part of being proficient and safe in IMC is knowing and adhering to your individual personal minimums. One way to approach this important task is to consider — honestly — how comfortable and proficient you are in the basic weather categories for aviation. VFR, marginal VFR (MVFR), IFR, and low IFR (LIFR). 

Be sure to account for day versus night operations in each category. For instance, I am very comfortable flying in day MVFR in my home airspace, but night is a different story. My own personal minimums also prohibit intentional operation into LIFR conditions. The minimums I set for IFR vary according to how much recent time I have flying in IMC, and how recently I have practiced flying instrument approaches. 

The Little Engine That Couldn’t 
The third major way that weather affects aviators is through its impact on aircraft performance. The temperatures in METARs, TAFs, and winds & temperatures aloft reports can give you a good indication of two weather phenomena that will undoubtedly sap your airplane’s operating capability: icing and high density altitude
An airplane is a machine, and all machines have performance limits. Consequently, a vital part of deciding whether to fly in weather likely to include such performance-reducing elements as icing or high-density altitude is to have a rock-solid understanding of what your airplane can and cannot do. The best piloting skills in the world cannot overcome the airplane’s physical performance limitations. 

A word about performance calculations: If the ground school memory of doing triple interpolations to calculate a two-foot difference in take-off distance has discouraged you from regular use of the performance charts for your aircraft, rest assured there is an easier way. Simply use the next highest numbers shown on the chart to get a “ballpark” estimate, and then add a 50–100 percent safety margin. If you calculate a take-off distance of 1,242 feet in high-density altitude conditions and the last two feet (or even the last 42 feet) really make a difference in whether you can operate or not, you should stop and consider whether it is wise to fly at all in those conditions. As the saying goes, there are no emergency take-offs

Learning after Landing 
A final thought: When you complete a challenging flight in weather, you may want nothing more than to go home and unwind. The immediate post-flight period, however, is one of the best opportunities to increase the weather knowledge and understanding that will guide effective decision making. Make it a point to learn something from every weather encounter. 

Flying or not,  when you look out the window or go outside, observe the clouds. What are they doing? Why are they shaped as they are? Why is their altitude changing? This simple habit will help you develop the ability to read clouds and understand how shape, colour, thickness, and altitude can be valuable weather indicators. As your cloud-reading skill develops, start trying to correlate the temperature, dew point, humidity, and time of day with the types of clouds that have formed. Take note of the wind, and try to visualize how it wraps around a tree or whips around the corner of a building. This exercise will help you become more aware of wind at critical points in your flight. 

Weather is a fact of life for pilots. Developing your weather knowledge and expertise is well worth the time and effort you put into it, because weather wisdom will help keep you and your passengers safe in the skies". 
 FLY SAFE!

ENGINE OPERATIONS

Acknowledgements: AOPA Air Safety Foundation    

Do you know what to do if the engine burps and coughs during the runup, or runs rough during cruise? In-depth systems knowledge can give you the tools needed to assess the engine’s actual condition. Aircraft engines are extremely reliable when properly cared for, and can deliver years of safe flight. That being said, not all pilots know as much as they should about the proper care and maintenance of engines, or that mechanical failure accounts for 15 to 20 percent of all accidents. Knowing how to manage a powerplant helps you fly more safely and can minimise the cost of flying. 

How to Make Your Engine Live Longer 
First and foremost – try to fly your engine at least an hour a week. Far more engines rust out than wear out. They rust because the oil drains off the cylinder walls and the moisture in the air then reacts with the iron in the engine. The rust creates roughness, which increases wear. Piston aircraft engines are made mostly of steel and aluminium, which expand and contract at different rates, depending on temperature. When flying at varying altitudes and from one climatic zone to another, temperature changes can be extreme. By keeping large engine temperature changes over a short period of time to a minimum, and within prescribed limits, the safety, reliability and longevity of the engine are significantly enhanced. 

For example, avoiding rapid descents at idlepower near your destination airport will help avoid “shock cooling,” which is the too-rapid cooling of hot engine metals. Shock cooling causes stress that can lead to cylinder head cracks. Good descent planning takes a little work, but your engine and passengers will thank you. This may take some negotiation with ATC, if IFR, or you may have to increase drag such as lowering the landing gear or flaps to keep airspeed and resultant engine cooling in check. 

Fuel Leaning
Pilots should lean appropriately anytime they are below 75% power, regardless of altitude. For most airplanes, correct mixture settings are detailed in the POH. As you gain experience with leaning, you’ll find that it saves gallons of fuel and helps the engine run better. Follow the POH mixture settings carefully; this is not the time to experiment on your expensive engine! 

Common Engine Problems (and solutions) 
·      What do I do if the engine runs rough during runup? 
Engine roughness while checking the magnetos during runup could indicate a fouled spark plug or other ignition system problem. Accelerate the engine to runup rpm and lean the mixture until the engine runs rough. Let the engine run for about 30 seconds. Enrich the mixture then check the mags again. If this doesn’t clear the roughness, have the ignition system checked by a mechanic before flying. 
·      What if the mag drop is more than 200 rpm? 
A larger than normal mag drop is not as critical as a rough mag. A smooth drop up to 200 rpm is fine. A drop greater than 200 rpm could indicate a mag-timing problem that should be checked. A mis-timed magneto can rob some power from the engine and also cause engine damage. 
·      Can I fly if the carb heat drop is 300 rpm or more during runup?
No. A large carb heat drop during runup, more than the typical 50 to 100 rpm, is caused by an exhaust leak inside the shroud where hot air is diverted to the carburettor. All exhaust leaks are dangerous and must be fixed, because firewall air leaks can allow exhaust fumes and possibly carbon monoxide from the engine compartment into the cockpit. A leak can also direct hot exhaust onto vulnerable components such as fuel lines and possibly cause a fire in the engine compartment. 
·      Is it possible for the carburettor to ice up during ground operations?
Yes. Under certain conditions carb icing can occur while taxying. If you don’t leave the carb heat on for at least 10 seconds during the runup check, the ice might not melt and could cause lower power output during take-off and possibly engine failure. If the carburettor is iced up during runup, carb heat application will result in an initial small rpm drop, then a rise higher than the runup rpm. 
·      How do I know if the engine is developing full power during take-off?
The engine must reach the specified static rpm range (before releasing the brakes) at full rpm. Check the POH for these numbers. If the aircraft can’t reach this rpm range on the ground there may be a problem with the tachometer indication or something wrong with the engine. Possible problems include a worn propeller (fixed-pitch), improperly set propeller governor (constant-speed), mis-timed magnetos, fouled spark plugs, clogged fuel injector nozzle, or a blocked muffler. 
·      What is a hot magneto and how can I troubleshoot this? 
A “hot” magneto is a magneto that can’t be turned off. If someone manually turns the prop with a hot mag, it could begin turningeven though the magneto switch is in the OFF position. You can easily check for a hot magneto:
·       During runup. If no rpm drop is noticed during the mag check on runup, you may have a hot mag. 
·       During engine shutdown. check for a hot mag by running the engine at idle and turning the ignition to Off. If the engine continues running with the ignition in the OFF position, the mag is hot. 
·      Can I take off if the oil temperature isn’t in the green? 
Yes, but check to make sure the engine picks up smoothly as the throttle is advanced. Throttle advancement should take several seconds from idle to full power. Cold oil doesn’t lubricate as well, and damage could occur if the oil isn’t warm enough. While engines can be started at very low temperatures, it is generally safer to preheat below -7C. Preheating improves oil lubrication, the fuel vaporizes for easier starting, and engine parts expand uniformly. 
·      My engine is so hard to start, especially when hot; what can I do about it?There are many causes of hard starting, including a weak battery, fouled spark plugs, worn magnetos, worn impulse couplings, fuel vapour lock, and improper technique. Fuel-injected engines can be difficult to start when the engine is hot because fuel can turn into vapor in fuel lines near the hot engine. With air bubbles/vapour in the fuel lines the engine will not start or will not run after starting. Follow POH instructions for hot starting, but be sure that the mechanical items mentioned above aren’t making the problem worse. 
·      My engine runs very rough while starting then smooths out as it warms up. Is there something wrong? 
Yes, there is a strong likelihood that you have a stuck valve. The valve sticks inside the cylinder head when the engine is cold and the metal parts are contracted. As the engine warms up, the valve eventually loosens and the engine runs smoother. A stuck valve is dangerous because the sticking can occur during normal operations, and it can cause catastrophic engine failure. Have this symptom checked thoroughly before flying. 
·      Can I hurt my engine by leaning too much? 
Yes, at higher power settings you can hurt the engine by over leaning. Follow the POH leaning instructions to avoid damage. There is one time that over leaning isn’t a problem and that is when running at just above idle power during ground operations. During a long taxy or a lengthy wait for take-off clearance, you can lean the engine aggressively without the risk of damage. Leaning on the ground helps prevent spark plug fouling. Just don’t forget to enrich the mixture before take-off. 
·      Is it okay to lean below 3,000 feet? 
Yes, you can lean the engine at any altitude. There is no reason not to lean during cruise; it saves gas and is better for the engine. While you will still see recommendations not to lean until reaching 3,000 or 5,000 feet, this advice is to keep pilots from forgetting to enrich the mixture before descending, and it is not related to any potential engine problems! 
·      I learned what to do if the engine fails, but what do I do if there is a partial power loss?
This is more likely to occur than a complete engine failure. The key is to determine if there is enough power to remain aloft to troubleshoot the problem. If the engine is losing power steadily, you’ll need to find a place to land quickly. An example might be a gradual loss of oil pressure; the end result is still total engine failure. A forced landing is in the very near future. A fuel line or muffler blockage could cause a partial power failure but leave enough power to stay level. In this case, you may be able to nurse the airplane to a nearby airport, but this will depend on terrain and weather. The bottom line for partial power is to treat it like a full engine failure. Troubleshoot as needed but plan to land at the nearest suitable airport. 

FLY SAFE!