Ground School: Seaplanes: Taxi & Takeoff, or “Get your floaties on”

Ground School: Seaplanes: Taxi & Takeoff, or “Get your floaties on”

Seaplanes and X-Plane 
Originally by Chuck Bodeen with edits for XP11 by yours truely ūüėČ

SMS_Beaver_Amphib_3

PECULIARITIES OF SEAPLANES
Once a seaplane is in the water and released from contact with a dock it is subject to weathervaning which is the tendency of the plane to face the wind. Its the same physical principle that keeps an arrow going straight ahead. The strength of this effect depends upon how much of the plane is behind the center of buoyancy.

Susitna_TMO_2007280

WEATHERVANING

Wheeled airplanes tend to pivot on the main landing gear wheels. Tail wheel planes have more side area exposed to the wind behind the main gear and are more subject to weathervaning than planes with tricycle gear. For seaplanes, the pivot is around the center of buoyancy which varies according to the pitch attitude in the water. At rest in the water a seaplane acts like a tail dragger. As it starts to move forward you must hold the yoke full back to counter the moment produced by the engine thrust. This raises the nose of the floats and there may be just as much wind-exposed side area ahead as there is behind producing virtually no weathervane effect. If this progresses into a deep plow the weathervaning can even be reversed! Finally, when the floats are moving fast enough to plane or up on-the-step, the effect of side winds can be almost the same as a taildragger again. Because of weathervaning there are only two practical taxiing speeds: slow and on-step although plowing is sometimes useful in turning.

DHC-3 Otter_FLOAT_17

Getting on the step requires the nose to be lowered and staying there is no easy task. You must use just the right amount of back pressure on the stick. Too much or too little will increase the drag and reduce speed. For taxiing, the throttle has to be reduced after you are on the step. Continuing on step with full power you will eventually reach the speed where the plane will lift itself off the water and then fly like a regular airplane. Lack of proper elevator control on a step taxi or takeoff run can result in porpoising which is a pitch oscillating condition that can increase in magnitude if you do not reduce elevator back pressure. Otherwise you may need to reduce power and abort the takeoff.

You may think that smooth water would be the best. Actually the rough water associated with a nice headwind allows you to takeoff at a lower waterspeed which reduces the drag on the floats. The fact that you are cutting along across the tops of the waves also reduces water drag. Depending upon the design of the floats, it is usually not recommended that you rotate as the plane lifts off the water.

Landing is made difficult by lack of visual contact with features on the ground and is particularly troublesome when coming in on glassy, smooth water. On the other hand, hitting rough waves at high speed can damage the floats, so you should always use the slowest possible water speed. Usually the waves will be caused by the wind, so even without a windsock you should be able to determine the proper heading for final approach. Never land parallel to the wave fronts rocking the boat is not a good idea.
So after landing what do you do? Once again you are at the mercy of the wind and with no ground-gear friction or brakes to help you steer. Sailing is a technique that allows you to take advantage of weathervaning and get where you want to dock, even by going backward in the water! After landing in a wind of, say, 20 knots you can set the engine to idle, and use the flight controls to turn the nose toward the dock. Go past the dock and then use power and control to finish.

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SAILING

Docking can be rather tricky because in a real plane you will be out of the cockpit standing on one of the floats. With the engine off, you may need a paddle (standard equipment on seaplanes) if you need just a bit more propulsion, or you might have to use your foot to keep the floats from hitting the dock too hard. There is a lot more to learn including the combined effects of currents and wind.

DHC-3 Otter_FLOAT_33

TAKEOFF

Here is how the takeoff goes. Once in the water, water rudders are lowered (more about that later) and gear is raised followed by a slow taxi out to the end of the takeoff area and a turn into the correct heading. At this point be sure the brakes are off. In the water, the brakes activate an anchor that will tie you to the spot you drop it. Now raise the water rudders, lower the flaps one notch, set the elevator trim for takeoff, and advance to full pitch and throttle. Pull back on the yoke to reduce drag by raising the leading edge of the pontoons. At about 40 knots, push the yoke forward to get the tail of the pontoons out of the water and have the ship plane on-the-step. At 60 knots the plane will lift off the water by itself. Come to think of it, this is quite a bit like a takeoff for a tail dragger, X-Plane has a default wave height which causes the ripples in the altitude, but I made the takeoff tests with little wind and wave height set to 0.3

Cessna_172SP_seaplane_2

TAKEOFF FROM THE WATER HAS FOUR CRITICAL STAGES

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START TAXI, UP ELEVATOR FOR PLOWING, DOWN ELEVATOR FOR ON-THE-STEP, AND THEN LIFT OFF

MODELING WATER RUDDERS
Real water rudders are usually placed at the rear of the pontoons or hull and are retractable so as not to be damaged or cause excessive drag during high speed operation. X-Plane has only one way to handle a water rudder. On the landing gear page, you can specify the longitudinal position, the area of the rudder, and the maximum angular movement. You have no control over the vertical position and X-Plane assumes that the water rudder is completely submerged if any part of the fuselage or floats is in the water.

LANDING HELP COMING SOON.

SMS_Beaver_Amphib_10

Still having trouble? Duct Tape can help! no seriously check this out:

https://forums.x-plane.org/index.php?/files/file/20632-duct-tape-10/

VATSIM Event PAJN – PAWG VFR Helper

VATSIM Event PAJN – PAWG VFR Helper

This flight is fairly straightforward, starting out in Juneau,

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out the Gastineau Channel,

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Flying south along Stephens Passage

400x300_AK_Stephens-Passage_4OrcasinRow

into Frederick Sound,

1_IMGP6845_Rev_Frederick_Sound_Sunset

Humpback whales bubble net feeding in the waters off Pinta Point, Frederick Sound, Inside Passage, Southeast Alaska

Humpback whales bubble net feeding in the waters off Pinta Point, Frederick Sound, Inside Passage, Southeast Alaska

then turning southeast past Farragut Bay,

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then flying south past Petersburg,

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then following Mitkof Island

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to Wrangell.

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Ground School: Decoding METARs

Ground School: Decoding METARs

The most important factor in determining which runway to use for takeoff or landing is arguably the weather. Whether you are on VATSIM, PE or offline (pun intended) you cab obtain current and forecasted weather reports with a METAR. This Class will help you decode a METAR and teach you what the abbreviations stand for.

Requesting a METAR

VATSIM

To request a text METAR on VATSIM using XSB, type this in the chat:
.metar CODE where CODE is the ICAO of the airport wanted.
i.e. Juneau, you would type .metar PAJN

X-PLANE

To request a METAR click your map on the airport desired to obtain the radio frequency needed to hear the ATIS and get the latest report.

A Typical Example

Lets examine a METAR for, say, Amsterdam, sexy women and good food! METARs right, sorry!

Keep in mind over in Europe they use meters instead of miles.

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

Decoded: METAR for Amsterdam Schiphol dated the 29th at 10h50z; wind direction is at 240 degrees and 15 knots; 9000 meters visibility; Rain, scattered cloud at 2500 feet; broken cloud at 4000 feet; Temperature is 10 degrees; dew point is 9 degrees; QNH is 1010; No significant change expected in the next few hours.

Decoding Legend

In the example above you get a vague idea of what some parts of a METAR mean, let’s break it down by sections and help you understand further.

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

The first section always contains the ICAO code for the airport

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

The second part is the date

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

After the date is the time of the report, which is always UTC

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

Then the wind direction in degrees and its speed in knots

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

Visibility in meters (for Europe, miles are used elsewhere)

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

RA means there is rain

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

SCT means there are scattered clouds

025 means they are at 2500 feet

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

BKN means there are broken clouds

040 means they are at 4000 feet

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

In this section the temperature is always first, followed by the dew point so:

  • The temperature is 10 degrees
  • The dew point is 9 degrees

EHAM 291050Z 24015KT 9000 RA SCT025 BKN040 10/09 Q1010 NOSIG

When you see NOSIG at the end of a METAR this means that no significant changes are expected in the next few hours

Decoders

There are some free tools online which allow you to decode METARs easily and I recommend their use to learn what all the abbreviations and terms within them mean.
http://heras-gilsanz.com/manuel/METAR-Decoder.html
http://www.iflightplanner.com/Resources/MetarTafTranslator.aspx
http://www.metarreader.com/

 

Lake Hood, Anchorage hot spot for floatplanes, will get three new hangars

Lake Hood, Anchorage hot spot for floatplanes, will get three new hangars

from ADN.

   A $15 million project underway to build new hangars at the Lake Hood Seaplane Base in Anchorage aims to alleviate the pent-up demand for housing smaller aircraft there.

A company called Lake Hood Hangars broke ground earlier this year on the first of three hangars. The other two are set to be built next year.

Steve Zelener, company owner, said there’s huge demand for more hangar space in Alaska’s largest city. Proximity to the lake itself also comes at a premium, and the new hangars will have nearby access to the¬†water.

The project also involves doubling the number of floatplane slips Zelener owns on Lake Hood from nine to 18.

Lake Hood Hangars developer Steve Zelener, center, confers with Remote Alaska Solutions construction company president Seth Kroenke, left, broker and project manager Stormy Jarvis, near right, and construction manager Igor Sapelnik, right, during a visit to the construction site of their first building on Tuesday.  (Erik Hill / Alaska Dispatch News)

Lake Hood Hangars developer Steve Zelener, center, confers with Remote Alaska Solutions construction company president Seth Kroenke, left, broker and project manager Stormy Jarvis, near right, and construction manager Igor Sapelnik, right, during a visit to the construction site of their first building on Tuesday.  (Erik Hill / Alaska Dispatch News)

The hangars, located on Aircraft Drive near a taxiway, will be about 24,000 square feet each. Taking up a bit more than 3 acres, the first massive building is still under construction, rising about 28 feet high and still without doors.

The rest of the land where the next two buildings will be located is still just dirt.

The hangar space will be both leased and sold, running from about $845,000 to $985,000 to buy and starting at about $1.35 per square foot per month to rent.

There were¬†nearly 8,000 registered aircraft in Alaska and around 3,300 of those were¬†registered in Anchorage as of the end of July, said Stormy Jarvis, manager of the hangar project. Most of those in Anchorage are small planes, she said, and that’s likely the case for the whole state.

“We see a need, and there’s also this waiting list for float slips at the lake,” she said. “There’s a hangar shortage. That’s a resounding message.”

One of six units in the first hangar building currently under construction faces the terminal at Ted Stevens Anchorage International Airport on Tuesday. (Erik Hill / Alaska Dispatch News)

One of six units in the first hangar building currently under construction faces the terminal at Ted Stevens Anchorage International Airport on Tuesday. (Erik Hill / Alaska Dispatch News)

Tim Coons, manager at the Lake Hood base, said the waitlist for slips is about 10-11 years old. The base, part of Ted Stevens Anchorage International Airport, has long claimed to be the busiest seaplane base in the world, he said. About 750 people at any given time have permits to park their planes there, he said.
“Most of the area around the lake has already been developed. This was one area that was still open,” Coons said. “Alaska has always presented a harsh environment. Just like anybody who would like to have the ability to keep a nice asset inside, airplane owners are no different.”
Even smaller planes can cost anywhere from $50,000 for something used, to a few million dollars for something new, said Zelener. Snow, cold and ice, as well as vandalism and other damage, are some of the reasons people want to keep their aircraft indoors.
“Outside elements are going to contribute to wear and tear of an aircraft before it has to be rebuilt,” said Seth Kroenke, president of Remote Alaska Solutions, the contractor on the project.
Integrated concrete form technology is being used for the Lake Hood Hangars buildings. The ICF blocks snap together and are then reinforced with horizontal and vertical steel bars before concrete is poured into the eight-inch gap. The technique provides strong, insulated walls with fire protection while also creating a strong sound barrier between units, said developer Steve Zelener. (Erik Hill / Alaska Dispatch News)

Integrated concrete form technology is being used for the Lake Hood Hangars buildings. The ICF blocks snap together and are then reinforced with horizontal and vertical steel bars before concrete is poured into the eight-inch gap. The technique provides strong, insulated walls with fire protection while also creating a strong sound barrier between units, said developer Steve Zelener. (Erik Hill / Alaska Dispatch News)

The hangars are designed with energy efficiency in mind, he said, and they use concrete insulated with foam to handle wide-ranging fluctuations in temperature.
The project has been an idea since 2010, Zelener said. He’s also the owner of Zelener Group, which has commercial real estate in Anchorage, Nome and Dutch Harbor.
Ground School: Preflight Planning

Ground School: Preflight Planning

ROLE OF PREFLIGHT PREPARATION

One of the most neglected acts of a pilot contemplating flight in an aircraft is that of proper preflight planning. The facts are well supported by aircraft accident statistics. The accident and fatality/serious injury statistics indicate an increase in the percentage of accidents during takeoff. Statistics taken from the National Transportation Safety Board files show that from 1979 through 1983, 728 persons died and 665 were seriously injured in 4,291 takeoff accidents. These accidents are significant to general aviation pilots, they represent about 20 percent of all general aviation accidents and about 16 percent of all fatalities and serious injuries annually.
Traditionally, pilots have emphasized the planning of the en route and approach/landing phases of flight; e.g., the route to be taken, en route and destination weather, en route and terminal facilities, applicable altitudes and fuel requirements. Accident data, however, indicate that too little preparation is made for the actual takeoff of the aircraft.
In order for pilots to fulfill their responsibilities to ensure the safety of the entire flight, it is necessary that they have adequate knowledge of elements involved in preflight planning. It is also necessary that they take time to analyze the conditions and study the various factors which would affect the takeoff, en route, and landing phases of flight.

KEY ELEMENTS OF PREFLIGHT PLANNING.

Charts.

https://skyvector.com/

http://vfrmap.com/

A basic element of preflight preparation requires the use of current navigational charts on which pilots can mentally review their intended route of flight. They may or may not wish to draw a line on the chart representing the true course. They should, however, review the projected path across the face of the chart for the location of good checkpoints, restricted areas, obstructions, other flight hazards, and suitable airports. For visual flight rule (VFR) pilot planning by either pilotage or dead reckoning, the Sectional Aeronautical Chart is an excellent choice. It is scaled at 1/500,000, or 8 miles to the inch. The physical characteristics of most landmarks, both cultural and geographic, are shown in great detail. The pilot should have little difficulty identifying the selected landmarks along the route of flight. Another popular chart is the World Aeronautical Chart (WAC). The scale of the WAC is 1/1,000,000, or 16 mile to the inch. Many states print aeronautical charts which are excellent for VFR navigation within their state boundaries. The pilot should realize, however, that all of these charts are designed primarily for VFR navigation and contain only limited information concerning radio aids and frequencies. The use of instrument flight rules (IFR) navigational charts for planning pilotage or dead reckoning VFR flights is not desirable for the following reasons:

  • Many airports used by the VFR pilot are not depicted or listed on the charts.
  • Very few geographic or cultural landmarks are provided.
  • The pilot should refer to the Airman’s Information Manual – Basic Flight Information and Air Traffic Control Procedures (AIM) – for the precise coverage of this information.

Most pilots are reluctant to admit to being disoriented or lost. Being lost can be an embarrassing and sometimes frightening experience. Pilots should carry appropriate and current aeronautical charts on all cross-country flights. The use of outdated charts may result in flights into airport traffic areas, control zones, or other restricted airspace without proper authorization. Having available the information contained in current charts will enhance the pilot’s ability to complete the flight with greater confidence, ease, and safety.

Route.

Since the shortest distance between two points is a straight line, a majority of pilots desire direct routes for most flights. Quite often there are factors that should be considered that may make a direct flight undesirable. Restricted and prohibited areas present obstacles to direct flights. In single-engine aircraft, pilots should give consideration to circumnavigating large, desolate areas. Pilots should also consider the single-engine service ceiling of multiengine aircraft when operating over high altitude terrain since the terrain elevation may be higher than the single-engine ceiling of the multiengine aircraft being flown. An example of this is a multiengine aircraft with a single-engine service ceiling of 6,000 feet being flown over terrain of 9,000 feet elevation. Pilots should be aware that the only advantage they may have over a pilot flying a single-engine aircraft may be a wider latitude in selecting a suitable forced landing area.

Airman’s Information Manual – Basic Flight Information and Air Traffic Control Procedures (AIM).

Part 91 of the Federal Aviation Regulations (FAR) states, in part, that each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. The AIM contains information concerning cross-country flight and basic fundamentals required for safe flight in the U.S. National Airspace System.

https://www.faa.gov/air_traffic/publications/media/aim.pdf

Airport/Facility Directory.

The Airport/Facility Directory, published by the National Ocean Service, lists airports, seaplane bases, and heliports open to the public, communications data, navigational facilities, and certain special notices such as parachute jumping, Flight Service Station (FSS)/National Weather Service (NWS) telephone numbers, preferred routes, and aeronautical chart bulletins.

https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/

Notices to Airmen (Class II).

https://www.faa.gov/air_traffic/publications/notices/

https://www.icao.int/safety/iStars/Pages/notams.aspx

Notices to Airmen (Class II) is issued biweekly and is divided into two sections. The first section contains those notices which are expected to remain in effect for at least 7 days after the effective date of the publication. National Flight Data Center (FDC) Notices to Airmen (NOTAMS) primarily reflect changes to standard instrument approach procedures. FDC NOTAMS also establish flight restrictions and correct data on aeronautical charts.

The second section contains special notices that, either because they are too long or because they concern a wide or unspecified geographical area, are not suitable for inclusion in the first section. The content of these notices vary widely and there are no specific criteria for inclusion, other than their enhancement of flight safety.

International Flight Information Manual.

http://webapp1.dlib.indiana.edu/virtual_disk_library/index.cgi/4300833/FID2415/ATPUBS/ifim/default.htm

The International Flight Information Manual is published quarterly for use of private flyers, businessmen, and nonscheduled operators as a preflight and planning guide for flights outside the United States.

International Notices to Airmen.

The International Notices to Airmen is a biweekly publication containing significant international NOTAM information and special notices which may affect a pilot’s decision to enter or use certain areas of foreign or international airspace.

Pilots should avail themselves of all appropriate charts and publications, including the AIM and NOTAMS.

Weather.

A weather briefing is an important part of preflight planning. An overview of the synoptic situation and general weather conditions can be obtained from public media (radio, TV, etc.) or by telephone from recorded sources. This will help the pilot to better understand the overall weather picture when obtaining a complete briefing from the FSS, or other organization that provides this service. Information on public media and recorded weather sources is contained in the Meteorology chapter of the AIM. This chapter also provides information on how to obtain a complete weather briefing, what to look for, and what to ask of the briefer to ensure that the pilot has all the weather necessary for the flight. The weather information should be weighed very carefully in considering the go/no-go decision. This decision is the sole responsibility of the pilot and compulsion should never take the place of good judgment.

https://www.aviationweather.gov/

https://flightplanning.navcanada.ca/

Navigation Log.

Precise flight planning of log items, such as pre-computed courses, time and distance, navigational aids, and frequencies to be used will make en route errors in these items less likely. Special attention should be given to fuel requirements, keeping in mind the need for an ample reserve as well as location of refueling points available as the preflight progresses.

Flight Plan (VFR).

This is not required by FAR, but is dictated by good operating practice. A flight plan not only assures prompt search and rescue in the event the aircraft becomes overdue or missing, but it also permits the destination station to render better service by having prior knowledge of your flight. It costs only a few minutes of time to file a flight plan and may be the best investment the pilot ever makes.

Aircraft Manual.

Aircraft manuals contain operating limitations, performance, normal and emergency procedures, and a variety of other operational information for the respective aircraft. Traditionally, aircraft manufacturers have done considerable testing to gather and substantiate the information in the aircraft manual. Pilots should become familiar with the manual and be able to refer to it for information relative to a proposed flight.

At this point I should mention EFBs as they make our lives easier, especially as sim-pilots. We’re already on a computer after all.

An¬†electronic flight bag¬†(EFB) is an electronic information management device that helps flight¬†crews¬†perform flight management tasks more easily and efficiently with less paper. It is a general purpose computing platform intended to reduce, or replace, paper-based reference material often found in the pilot’s carry-on flight bag, including the aircraft operating manual, flight-crew operating manual, and navigational charts (including moving map for air and ground operations). In addition, the EFB can host purpose-built software applications to automate other functions normally conducted by hand, such as performance take-off calculations.

https://fltplan.com/

https://foreflight.com/

KEY ELEMENTS DURING TAKEOFF PHASE.

The importance of thorough preflight preparation which considers possible hazards to takeoff cannot be over-emphasized. The following elements, which should be carefully considered, continue to emerge as factors in takeoff accidents: a. Gross Weight.

Maximum allowable gross weight is established for an aircraft as an operating limitation for both safety and performance considerations. The gross weight is important because it is a basis for determining the takeoff distance. If gross weight increases, the takeoff speed must be greater to produce the greater lift required for takeoff. The takeoff distance varies with the square of the gross weight. As an example, for an aircraft with a relatively high thrust-to-weight ratio, a 10 percent increase in takeoff gross weight would cause:

  • a 5 percent increase in speed necessary for takeoff velocity;
  • at least a 9 percent decrease in acceleration; and,
  • at least a 21 percent increase in takeoff distance. NOTE: For aircraft with relatively low thrust-to-weight ratios, the figures are slightly higher.

Operations within the proper gross weight limits are outlined in each operator’s manual. Gross weight and center of gravity (CG) limits should be considered during preflight preparation. Weight in excess of the maximum certificated gross weight may be a contributing factor to an accident, especially when coupled with other factors which adversely affect the ability of an aircraft to take off and climb safely. These factors may range from field elevation of the airport to the condition of the runway. The responsibility for considering these factors before each flight rests with the pilot. b. Balance.

A pilot must not only determine the takeoff weight of the aircraft, but also must assure that the load is arranged to fall within the allowable CG limits for the aircraft. Each aircraft manual provides instructions on the proper method for determining if the aircraft loading meets the balance requirements. The pilot should routinely determine the balance of the aircraft since it is possible to be within the gross weight limits and still exceed the CG limits.

An airplane which exceeds the forward CG limits places heavy loads on the nosewheel and, in conventional landing gear airplanes, may, during braking, cause an uncontrollable condition. Furthermore, performance may be significantly decreased and the stall speed may be much higher.

An airplane loaded in a manner that the CG exceeds the aft limit will have decreased static and dynamic longitudinal stability. This condition can produce sudden and violent stall characteristics and can seriously affect recovery.

Pilots exceeding CG limits in helicopters may experience insufficient cyclic controls to safely control the helicopter. This can be extremely critical while hovering downwind with the helicopter load exceeding the forward CG limit.

Ice and Frost.

http://www.skybrary.aero/index.php/Ice_Formation_on_Aircraft

Ice or frost can affect the takeoff performance of an aircraft significantly. Pilots should never attempt takeoffs with any accumulation of ice or frost on their aircraft. Most pilots are aware of the hazards of ice on the wings of an aircraft. The effects of a hard frost are much more subtle. This is due to an increased roughness of the surface texture of the upper wing and may cause up to a 10 percent increase in the airplane stall speed. It may also require additional speed to produce the lift necessary to become airborne.

Once airborne, the airplane could have an insufficient margin of airspeed above stall such that gusts or turning of the aircraft could result in a stall. Accumulation of ice or frost on helicopter rotor blades results in potential rotor blade stalls at slower forward air speeds. It could also result in an unbalanced rotor blade condition which could cause an uncontrollable vibration.

Density Altitude.

http://www.skybrary.aero/index.php/Density_Altitude

Aircraft instruments are calibrated to be correct under one set of conditions. Standard conditions represent theoretical sea level conditions, 59 degrees Fahrenheit and 29.92 in Hg. As higher elevations are reached, both temperature and pressure normally decrease. Thus, density altitude is determined by compensating for pressure and temperature variances from the standard conditions. A pilot must remember that as density altitude increases, there is a corresponding decrease in the power delivered by the engine and the propellers or rotor blades. For airplanes, this may cause the required takeoff roll to increase by up to 25 percent for every 1,000 feet of elevation above sea level. The most critical conditions of takeoff performance are the result of a combination of heavy loads, unfavorable runway conditions, winds, high temperatures, high airport elevations, and high humidity.

The proper accounting for the pressure altitude (field elevation is a poor substitute) and temperature is mandatory for accurate prediction of takeoff data. The required information will be listed in the aircraft manual and should be consulted before each takeoff, especially if operating at a high density altitude or with a heavily loaded aircraft.

Effect of Wind.

Every aircraft manual gives representative wind data and corresponding ground roll distances. A headwind which is 10 percent of the takeoff airspeed will reduce the no-wind takeoff distance by 19 percent. A tailwind which is 10 percent of the takeoff airspeed, however, will increase the no-wind takeoff distance by about 21 percent.

Although this consideration is basic to a successful takeoff, the number of accidents involving the selection of the wrong runway for the existing wind and taking off into unfavorable wind conditions indicates a need for many pilots to reevaluate their preflight planning to ensure that the effect of wind is considered fully.

Runway Condition.

There are more than 14,700 airports in the United States, each with runway, having various surface compositions, slopes, and degrees of roughness. Takeoff acceleration is affected directly by the runway surface condition and, as a result, it must be a primary consideration during preflight planning.

Most aircraft manuals list takeoff data for level, dry, hard-surfaced runways. The runway to be used, however, is not always hard-surfaced and level. Consequently, pilots must be aware of the effect of the slope or gradient of the runway, the composition of the runway, and the condition of its surface. Each of these can contribute to a failure to obtain/maintain a safe flying speed.

The effective runway gradient is the maximum difference in the runway centerline elevation divided by the runway length. The FAA recognizes the effect of runway gradient on the takeoff roll of an aircraft and has published limits on the maximum gradients. For general aviation VFR airports the maximum longitudinal runway grade is 2 percent and the longitudinal runway grade change is 2 percent maximum. Furthermore, the takeoff length for a runway must be increased an additional 20 percent for each 1 percent of change in effective gradient to a maximum allowable effective gradient change of 2 percent.

Since the runway gradient has a direct bearing on the component weight of the aircraft, a runway gradient of 1 percent would provide a force component along the path of the aircraft which is 1 percent of gross weight. In the case of an upslope, the additional drag and rolling friction caused by a 1 percent upslope can result in a 2 percent to 4 percent increase in the takeoff distance and subsequent climb.

Frequently, the only runway at an airport has a slope. When determining which direction to use for takeoff, pilots must remember that a direction uphill, but into a headwind, is generally preferred to a downhill takeoff on a downsloping runway. Factors such as steep slope, light wind, etc., however, make an uphill takeoff impractical.

It is difficult to predict the retarding effect on the takeoff run that water, snow/slush, sand, gravel, mud, or long grass on a runway will have, but these factors can be critical to the success of a takeoff. Since the takeoff data in the aircraft manual is predicated on a dry, hard surface each pilot must develop individual guidelines for operations from other type surfaces. g. Cold Weather Takeoffs. The following is an excerpt taken from AC 91-13C, Cold Weather Operation of Aircraft. “Takeoffs in cold weather offer some distinct advantages, but they also offer special problems.

A few points to remember are:

“Do not overboost supercharged or turbine engines. Use the applicable power charts for the pressure altitude and ambient temperature to determine the appropriate manifold pressure or engine pressure ratio. Care should be exercised in operating normally aspirated engines. Power output increases at about 1 percent for each ten degrees of temperature below that of standard air. At -40 degrees F, an engine might develop 10 percent more than rated power even though RPM and MP limits are not exceeded.

“On multiengine aircraft it must be remembered that the critical engine-out minimum control speed (Vmc) was determined at sea level with a standard day temperature. Therefore, Vmc will be higher than the published figure during a cold weather takeoff unless the power setting is adjusted to compensate for the lower density altitude.

“With reciprocating engines, use carburetor heat as required. In some cases, it is necessary to use heat to vaporize the fuel. Gasoline does not vaporize readily at very cold temperatures. Do not use carburetor heat in such a manner that it raises the mixture temperature to freezing or just a little below. In such cases, it may be inducing carburetor icing. An accurate mixture temperature gauge is a good investment for cold weather operation. On some occasions in extremely cold weather, it may be advisable to use carburetor heat on takeoff.

“If icing conditions exist, use the anti-ice and deice equipment as outlined in the Airplane Flight Manual. If the aircraft is turbine powered, use the appropriate power charts for the condition, bearing in mind that the use of bleed air will, in most cases, affect the aircraft’s performance.”

SUMMARY.

Preflight preparation is the foundation of safe flying. Accident statistics of recent years indicate that adequate preflight preparation is lacking in many cases. As a result, while the number of general aviation accidents and approach and landing accidents has declined, takeoff accidents have increased. Statistics indicate that takeoff accidents occur because elements of the preflight preparation were:

  • not assigned the proper importance,
  • not incorporated into the preflight routine, or
  • pilots did not anticipate potential takeoff emergencies and the required procedures to follow:

RECOMMENDATION.

To enhance the safety of flying, pilots are encouraged to:

  • form good preflight planning habits and review them occasionally,
  • be thoroughly knowledgeable of the hazards and conditions which would represent potential dangers, particularly during takeoff.
  • be aware of the capabilities and limitations of their aircraft.

 

HOMEWORK.

I’ll start you off easy. Plan some flights! Use your preferred method of finding a destination and plan the appropriate route there.

Fill out a Nav Log, do some fuel calculations, look up the weather and NOTAMs.

You taking passengers? Don’t forget about their weight and baggage.

We’re flying VFR in a C172SP for now so plan with that in mind.

Have fun with this often neglected part of flying be it real or virtual, if yo want a realistic, safe, informed flight you’ve got to preflight plan.

 

Special Thanks to http://www.skybrary.aero a great resource.