Thursday, 29 January 2015
Whilst satellite navigation will no doubt one day become our principal means of getting from one place to another, the current GPS system is fallible and should be used with knowledge and caution, not blind faith. The satellite clock may drift off time, the satellite may stray from its orbit, or its transmitter may simply fail. It can take up to two hours for such failures and errors to be resolved. Position errors up to 2 km have been reported. Also, the GPS signal received from the satellite is at very low power and is vulnerable to interference.
Equipment permanently installed in an aircraft must be fitted in a manner approved by the CAA. Where a hand-held unit is carried it, its antenna and any leads and fittings should be secured in such a way that they cannot interfere with the normal operation of the aircraft’s controls and equipment, and do not inhibit the pilot’s movements or vision in any way.
Before using GPS equipment in the air, pilots should learn about the system in detail. If no suitable instructor is on hand, practise using the equipment on the ground in advance.
Plan the flight and prepare a map and log in the normal way. Enter route information from the log directly into the receiver as a ‘Flight Plan’. Deleting/moving/changing the names of existing User Waypoints should be prohibited if the GPS is operated by more than one pilot. If there is no map, or it is too small to be of practical use, compare each individual track and distance as displayed on the GPS screen with your previously prepared flight log.
DO NOT RELY ON AN OUT OF DATE DATABASE.
The GPS system should NEVER be used in isolation. The risk of loss/degradation of the signal, with the attendant possibility of a position error, is genuine. More importantly, the risk of human error in data input and display reading is high & such errors can go unnoticed until it is too late. To avoid becoming totally dependent on the GPS, ask yourself two questions regularly throughout the flight:
· Does the GPS agree with at least one other independent source of navigation information?
· If the GPS quits completely, right now, can I continue safely without it?
If the answer is “Yes” to both questions, you can continue to use the equipment for guidance. However, if the honest answer to either one of the questions is “No”, then you should establish navigation by some other means.
Re-programming in the air is likely to produce human error. To avoid the need, pre-plan possible route changes, for example around controlled airspace in case you cannot obtain clearance, or around high ground in the event of bad weather. Note the ICAO designators of all suitable diversion aerodromes.
If you do need to change your planned route in flight, make at least a rough set of mental calculations (and note them down) BEFORE you turn onto the GPS track. Then if your new heading does not agree with your mental calculations, you will know there is an error somewhere for correction. Check the new route on a map for terrain, any NOTAM activity, and controlled or restricted airspace.
Pilots have been known to produce and follow their own approach procedures using GPS information. User-defined approaches can be dangerous and are not authorised.
MEMORY JOGGER #7
An overloaded aircraft may fail to become airborne, while an out-of-limits centre of gravity seriously affects stability and controllability. Pilots must appreciate the effects of weight and balance on the performance and handling of aircraft, particularly in combination with other performance reducing factors, such as long/wet grass, a 'tired' engine, severe or un-coordinated manoeuvres, turbulence, high ambient temperatures and emergency situations.
The effects of overloading include:
· reduced acceleration/greater take-off speed, take-off run, & distance to clear a 50 ft. obstacle
· decreased angle of climb/reduced obstacle clearance capability after take-off
· excessive loads on landing gear, especially if the runway is rough
· reduced ceiling, rate of climb, & range
· impaired manoeuvrability & controllability
· increased stall speeds
· increased landing speeds, requiring a longer runway
· reduced braking effectiveness & structural strength margins
· with twin-engine aircraft, failure to climb/maintain height on one engine
Forward and aft limits on the centre of gravity (cg) are established during type certification; they are the extreme cg positions at which longitudinal stability requirements can be met.
Exceeding the forward cg limit usually results in:
· difficulty in rotating to take-off attitude
· increased stall or minimum flying speed against full up elevator
· extra tail downforce requiring more lift from wing, resulting in greater induced drag. This means higher fuel consumption and reduced range
· inadequate nose up trim in landing configuration, necessitating a pull force throughout the approach making it more difficult to fly a stable approach
· difficulty in flaring/holding the nose wheel off after touch down. Inability to hold the nose up during a bounce can result in damaged nose landing gear and propeller
· increased loads on the nose landing gear
Exceeding the aft cg limit usually results in:
· pitch-up at low speed & high power, leading to premature rotation on take-off, or inadvertent stall in the climb or during a go-around
· on a tail wheel type, difficulty in raising the tail/maintaining directional control on the ground
· difficulty trimming, especially at high power
· longitudinal instability, particularly in turbulence, with possible reversal of control forces
· degraded stall qualities to an unknown degree
· more difficult spin recovery, unexplored spin behaviour, delay in/inability to recover
(Acknowledgements: Goldi Productions Ltd.)
Most problems related to disorientation can be traced to the inner ear, a sensory organ about the size of an eraser on a pencil.
The inner ear is similar to a three-axis gyro. It detects movement in the roll, pitch, and yaw axes that pilots know so well. When the sensory outputs of the inner ear are integrated with appropriate visual references and spatial orientation cues from our bodies, there is little chance to experience disorientation.
The problem occurs when the outside visual input is obscured, leaving just the output from the inner ear — and that's when trouble can start.
A pilot suffering from spatial disorientation has difficulty in determining how they are flying in relation to the horizon.
Fluid in the inner ear reacts only to rate of change, not a sustained change. For example, when you initiate a banking left turn, your inner ear will detect the roll into the turn, but if you hold the turn constant, your inner ear will compensate and rather quickly, although inaccurately, sense that it has returned to level flight.
As a result, when you finally level the wings, that new change will cause your inner ear to produce signals that make you believe you're banking to the right. This is the crux of the problem you have when flying without instruments in low visibility weather.
Even the best pilots will quickly become disoriented if they attempt to fly without instruments when there are no outside visual references. That's because vision provides the predominant and coordinating sense we rely upon for stability.
The obvious method to prevent disorientation is the instrument rating. But, that rating alone is no automatic guarantee, because there is no such thing as "knowing how to fly on instruments."
Practice your IFR skills - you are either trained and current, or you are unqualified!
(Acknowledgements: Goldi Productions Ltd.)
Thursday, 22 January 2015
· Always supervise the refuelling of your aircraft because you are responsible for what and how much goes into the tanks. JET-A1 and AVGAS mistakes are easily made, and diesel-engine types are becoming ever more popular
· Ensure that earth wires are attached before delivery begins and that the nozzle is earthed. Make sure a fire extinguisher is available
· After refuelling, personally check all filler caps and access panels for security
· Make sure hoses and earth wires are wound back clear after use
· When you sign or pay for the fuel, double-check the invoice for the correct type/grade of fuel and quantity. (JET-A1 in a piston-engine aircraft has been discovered at this stage)
MEMORY JOGGER #5
As air moves through a carburettor its temperature drops and, if conditions are right, water vapour in the air can condense and form ice. Most carburetted aircraft are equipped with a control that routes heated air to the carburettor to melt the ice and keep it from re-forming.
Applying carb heat enriches the mixture and increases fuel consumption for a given power setting because the heated air is less dense than ambient air. Pilots should therefore lean while operating with carb heat and enrich when it’s no longer needed.
Accident Report: A private pilot was en-route from Boston to an airport in northern Virginia. Shortly after passing Dulles Airport, the engine failed due to fuel exhaustion. The airplane was destroyed and the occupants were severely injured in the off-airport landing. The pilot stated that he had made the trip many times before with enough fuel to reach his destination but, on this flight, carburettor heat was applied shortly after take-off and remained on until the landing. The richer mixture resulted in fuel exhaustion ten miles from his destination.
MEMORY JOGGER #4
LEANING THE MIXTURE
The performance, range, and endurance figures listed in the POH are based on a properly leaned engine. The POH can’t tell you how fast, far, or long you’ll fly unless you lean the mixture. Although many pilots think that leaning is only for high altitudes, the truth is that most engines can be safely leaned at any altitude so long as they are operating at less than 75 percent power. (Consult your POH for information on calculating percentage of power.)
Failure to lean is commonly cited as a factor in fuel exhaustion accidents. Learn how to lean your engine, and make leaning a habit on every flight. Some general guidelines are presented below. For specific information, see your airplane’s POH or the engine manufacturer’s operating instructions.
On basic airplanes, set cruise power and lean the mixture until the engine runs rough. Then slowly enrich the mixture until the engine runs smoothly. You may see a slight increase in rpm before the engine starts to roughen. If you need to climb to a higher cruising altitude, enrich the mixture before adding power (if you’re at or above 75 percent power) and then lean again when level at your new altitude.
Leaning for take-off:
At high-density-altitude airports, you’ll have to lean before take-off to maximize engine power. Consult your POH for details.
Tip: Two typical mixture settings are “best power” and “best economy.” Best power provides the highest speed for a specific power setting. Best economy trades some of that speed for decreased fuel consumption, and gives the best mileage available at a particular power setting.
MEMORY JOGGER #3
MANAGING FUEL IN FLIGHT
Most low-wing single-engine aircraft cannot feed from both fuel tanks at the same time and so have LEFT, RIGHT and OFF fuel selector positions. To maintain lateral balance, try to keep the tanks as equal as reasonably possible. For example, after take-off fly for half an hour on one tank, and then an hour on the other, switching hourly thereafter. This should keep you from having more than a half-hour’s fuel imbalance at any given time.
As the tanks are sited lower than the engine, fuel must be pumped. Fuel Pump use can vary from one aircraft to another. Some designs require the boost pump to be on for landing and take-off; in others the boost pump is to be used only at high altitude or when the mechanical pump fails. Pilots must be familiar with fuel pump operation for each aircraft they fly.
Safety tip: When fuel tanks are not full, ‘over-zealous’ on-ground manoeuvring could move fuel in the tank away from the outflow ports, so avoid sharply-accelerating turns when given permission to enter the runway for take-off with immediate clearance.
In-Flight, deviations for weather, stronger headwinds, or the discovery of low fuel condition may require you to maximize fuel economy. To conserve fuel:
• Slow down: You’ll burn less fuel if you cruise at a lower power setting.
• Fly with the wind: If you have a choice of equidistant fuel stops, pick the one that’s downwind. You may have to backtrack but you’ll burn less fuel and get there faster.
• Lean for best economy: Consult the POH for best economy/long endurance power settings and leaning procedures
Warning: Fuel consumption figures given in the POH are based on a properly leaned engine operating at a specific power setting. One way to get to know your actual fuel consumption is to estimate how much fuel your airplane will take at each fuel stop. Comparing this with what actually goes into the tanks is a good way to develop “fuel sense.”
Safety tip: In flight, recalculate range and endurance hourly. Compare your calculation with distance to destination, to confirm you have adequate fuel reserve and to allow timely needed adjustment to your flight plan. Your GPS provides accurate information about ground speed and time en route, which are essential parameters for determining adequate fuel reserves.
Accident Report: Before departing cross-country, the pilot of a Piper Cherokee Six requested that his two main tanks and two auxiliary tanks be “topped”, but the Re-fueller subsequently stated that only the mains were filled. En route, the pilot became aware of a low fuel condition. The engine lost power about five miles out and an off-airport landing was made. A passenger stated that the pilot had considered landing for fuel but elected to continue to destination. The pilot and two passengers died and three remaining passengers were seriously injured, indicating the importance of checking actual fuel uplift against requirement before departing.
Sunday, 11 January 2015
The following points should be borne in mind when flying in winter:
• Stay out of icing conditions for which the aircraft has NOT been cleared
• Note freezing level in the aviation weather forecast. Don’t go unless the aircraft is equipped for the conditions
• Have warm clothing available for pre-flight and in case of heater failure or forced landing
• Mud, snow and slush will lengthen take-off and landing runs. Work out your distances
• Remove all frost, ice and snow from the aircraft – there is no such thing as “a little ice”!
• Check carefully that all essential electrical services, especially pitot heat, are working properly
• Check that the heater and demister are effective. Watch out for any signs of carbon monoxide poisoning
• Be extra vigilant for carb ice
• If ice does start to form, act promptly, get out of the conditions by descending, climbing or diverting
• If you encounter ice, tell ATC so that others can be warned
• During the approach if you suspect tail-plane ice, or suffer a severe pitch down, RETRACT THE FLAPS
• If you have to land with an iced up aeroplane, add at least 20% to the approach speed
• Snow-covered, icy or muddy runways will make the landing run much longer and crosswinds harder to handle
Thursday, 8 January 2015
THE GENERAL AVIATION SAFETY TOPIC OF THE MONTH
“SINGLE-PILOT RESOURCE MANAGEMENT (SRM)”
Single-pilot resource management is defined as the managing of all resources available to a pilot, both on-board the aircraft and from outside sources prior to and during a flight to ensure its successful conclusion.
It is about gathering information, analysing it, and taking decisions based on it.
It requires a pilot to perform a number of mental tasks in addition to the physical task of basic aircraft control, including:
· Situational awareness
· Task management
· Automation management
· Risk management
· Aeronautical decision-making
· CFIT (controlled-flight-into-terrain) awareness
This can be a challenge for GA pilots, whose flying experience may be limited, and the incorporation of SRM into GA pilot training is an important step forward in aviation safety.
When a flight is operated by a single pilot, that pilot has various inside and outside resources available to assist with the flight. The key is how to identify and effectively use these resources, which include:
· Passengers, even those with no flying experience. Use them to read out checklist items or watch for traffic. With a bit of instruction, they can also help listen for radio calls or assist with switching radio frequencies
· If the aircraft is so equipped, one could teach frequent passengers some basic programming skills for the moving map and multifunction displays
· Reading the checklist out loud, and touching the appropriate switch or control. Talk to yourself – as a solo flyer nobody’s listening!
· On-board equipment, both panel-mounted and hand-held, is an important internal resource. Today’s technology offers an incredible range of information to assist with overall situational awareness, navigation, weather information, and much more. The key to benefiting from this resource is to know your devices: long before you leave the ground, know what information is available and make sure you know how to access it without unduly diverting your attention from essential aircraft control duties.