What is long-distance flying? For our purposes, it can be defined as flying close to the aircraft's maximum range, with limited alternatives to land short of the destination if something happens. This is typical of an over-water flight.
Our first long flight is mandated by the training requirements set out in Federal Aviation Regulation 61.109(a)(5). A cross-county flight of at least 150 nautical miles total distance must be accomplished (one leg must have a straight-line distance of at least 50nm). While these may be the longest flights we ever take until we fly on our own with a private certificate, they don't really qualify as true long-distance flying. In most aircraft, 150 nm is nowhere near maximum range, and even in a slow training aircraft, it means being aloft only an hour and a half to two hours. Likely there were many alternative landing sites along any longish leg. And the FAA requires no flight training that includes an over-water leg.
Once we have the private pilot certificate, we are faced with decisions that did not arise in training. Flying about 200 nm from New Jersey to Virginia crosses the Delaware and Chesapeake bays. A flight from Saginaw, Michigan, to Oshkosh, Wisconsin, crosses Lake Michigan. Both flights are well within range of most aircraft, but they involve over-water legs. These flights require a lot of additional careful planning. What's more, the pilot in command needs to pay strict attention to fuel management, weather, and other factors. Here are some rules for planning and executing a long-distance flight.
Employ the maximum-range power setting early. Efficient fuel use is most effective when practiced over a long period of time. Deciding to stretch fuel late in a flight is much less effective. Know your aircraft's fuel capacity and fuel flow. The most frequently expressed excuse for running out of fuel was that the pilot did not know that there was so little fuel aboard.
Always carry full fuel, or at least the maximum fuel possible considering weight and balance. Consider carrying less baggage in exchange for maximum fuel. Even when carrying maximum fuel, flying lighter will extend the aircraft's range. The wing has to provide less lift if the airplane is lighter, and thus heavier aircraft must be flown at a greater angle of attack. This results in greater induced drag, and therefore less range.
A long flight -- or even a short one -- will not be completed if the engine fails, and the most common cause for engine stoppage is lack of fuel reaching the engine.
Fuel starvation occurs when fuel aboard does not reach the engine. Fuel may be sequestered because of a mechanical failure -- a jammed fuel valve or blocked vent that prevents fuel from reaching the engine. However, a more frequent cause of fuel starvation is a pilot who doesn't understand the aircraft's fuel system. The larger the aircraft, the more complex the fuel plumbing, and the more likely a pilot could err in managing fuel.
Keep close tabs on the weather along your route and at the destination. Weather forecasts obtained before long flights will likely be stale after several hours. Maintaining an en-route weather watch, paying particular attention to current conditions at the destination and alternate airports, is increasingly important because the time aloft is greater. The longer the distance, the more a promise of good weather is required. This may mean delaying the flight a few hours or even days.
Winds aloft are dominant factors in long-distance flying, and they are also unpredictable. As winds-aloft forecasts are notoriously inaccurate, winds must be carefully monitored in flight.
- If there is any doubt about the completion of a long flight, make a diversion as early as possible.
Accurate navigation is imperative. An error will consume unplanned fuel and can be costly.
It is a good principle to consider a radius of operation while in flight. At takeoff we have the largest radius of operation, and that radius progressively shrinks as the flight proceeds (see "Risk Management," p. 46).
Engine out -- what will you do?
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Long flights could cover rugged mountainous areas, barren deserts, or murky swamps. A flight that traverses water comes with additional planning concerns. What will you do if the aircraft's engine loses power? Are you prepared for a forced water landing? Do you have life vests, an emergency locator beacon, and perhaps a raft -- all of which must be counted in your weight calculations? Assume that you cannot make a forced landing on land, or a diversion to an airport. You will need to plan carefully. Consider the available survival gear for any flight over inhospitable terrain.
After engine failure, most light single engine aircraft glide about 1.5 nm per 1,000 feet of altitude. Whether or not you reach dry land or an airport from some point over water depends on your altitude. The radius of action is directly proportional to the aircraft's height above the ground, modified of course by winds.
Consider the example of crossing Lake Michigan -- 50 nm of water -- on the way to Oshkosh. Assuming you cross at 10,500 feet westbound (or about 10,000 feet above the surface) your aircraft has a potential glide distance of 15 nm. Thus, the wet footprint -- the distance during which an engine stoppage will result in a water landing -- is 20 nm.
However, if you wish to glide to an airport, the wet footprint is greater. Airports are typically inland, and you must plan to arrive over an airport with 800 to 1,000 feet of altitude to spare so that you can make maneuvers in the traffic pattern. Thus, the wet footprint crossing Lake Michigan now is 25 to 30 nm. Clouds or the aircraft's operational ceiling may limit your ability to fly higher to reduce the footprint. Most piston-engine general aviation aircraft cannot eliminate a wet footprint on a 50-nm overwater flight. Consult the airplane's pilot's operating handbook, and calculate the maximum distance that you can fly without a wet footprint. You will need to know the glide ratio and the maximum practical altitude. Then simply multiply.
There are other considerations when flying over water: the point of no return and the equal time point.
Let us say that as you get about halfway across Lake Michigan westbound, airports on the west side of the lake go below minimums or a line of unforecast thunderstorms seems to be blocking the lake's western shore. How far west can you go for a look and still have enough fuel to safely return to the eastern shore? There may be a point at which there is insufficient fuel reserve to turn around. You don't want to be enticed into undesirable conditions. To calculate the point of no return, you must know how much fuel (in hours and minutes) is on board when you cross the last landing point in Michigan, as well as your airspeed and ground speed (see "Calculating the point of no return," p. 44). The equal time point is the point at which continuing across the lake or reversing course are equally good options when considering fuel. In an emergency, this will tell you which way will lead to a quicker landing (see "Calculating the equal time point," below).
These calculations assume that winds aloft do not change, and the wind vector is constant for the entire flight. That cannot be guaranteed, and it is one reason that you cannot use fuel reserves in the calculation.
When flying over water do not miss the obvious. The Delaware and Chesapeake bays offer alternates at mid-crossing that are closer than either returning or continuing. One is Wildwood, New Jersey. This changes the points of no return and equal time.
An airplane does not fly differently over water than over land. However, planning required to make a long-distance water crossing safe is more complex than for a typical cross-county flight.
Dr. Ian Blair Fries is a CFI, senior aviation medical examiner, and ATP, and holds a Lear 35 type rating. He serves on the AOPA Air Safety Foundation Board of Visitors and is cochairman of the AOPA Board of Medical Advisors.
Want to know more?
Links to additional resources about the topics discussed in this article are available at AOPA Flight Training Online.
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