At this point, you should have enough weather information to make a choice of route and altitude. Unless a detour is indicated because of weather, high terrain, or restricted airspace, you should be looking for the route that will get you where you’re going in the shortest pos- sible time. This usually means the nearest thing to a straight line be- 66
tween departure and destination. For long trips, you should consult an IFR planning chart, which shows the airways from coast to coast and border to border. (The Jeppesen service includes such a chart, or you can purchase one from the government.) You’ll generally find an airway nearly parallel to the direct route. Unless you look at the big picture, you may miss the airway that goes all the way from point A to point B; filing one airway is so much easier than a bunch of short segments, and it eases the pain for ATC, too.
Preferred routes, with major terminals and the airways that ATC would like you to use when traveling certain city pairs, are listed in the Avigation section of the Jepp service and in the AIM. Preferred routes are the fastest, most efficient way to go. Although not always the shortest, they are ultimately the fastest because that’s the way ATC is going to clear you, so you are better off filing the preferred route at the outset. (See Chap. 5, IFR Flight Plans, for the proper way to file a devious route because of weather or limiting altitudes.)
ATC’s preferred routes can also be used to advantage when you plan a trip to a point short of the destination terminal mentioned in the route listing. If you use the preferred route as far as you can, you’ll get better service from ATC.
Standard Instrument Departures (SIDs) are really short-range preferred routes limited to the departure phase of an IFR trip, and if you frequently fly from an airport with published SIDs, you’ll find it worthwhile to have these charts in your flight kit. When SIDs are in use, plan your flight accordingly by noticing the point at which the SID puts you into the enroute structure. Your enroute planning should begin at the VOR (or other fix) specified as the end of the SID and use the preferred route, if applicable, from that point to destination.
At an increasing number of airports, STARs are coming into use. Not heavenly bodies to be wished upon or used for celestial naviga- tion, these STARs are the acronymic way of saying Standard Terminal Arrival Routes. They are just SIDs in reverse and provide specific routings into a terminal area. When you are flight planning to an air- port with a published STAR (big airports may have several), end the airways portion of your route at the VOR or intersection that is the en- try, or gate, to the STAR procedure. Using the STAR when you file your flight plan will save everybody time and trouble because you won’t have to be given a change of routing along the way. STARs are near-exclusive features of high-speed, high-altitude operations.
The ultimate in preflight planning, at least from a routing stand- point, would see you departing under the guidance of a SID, pro- ceeding on your way via a preferred route, and winding up the flight
Chapter Six
with a Standard Terminal Arrival Route (STAR). The key is to realize that the air route structure is a huge system, and where the designers have identified channels (preferred routes, SIDs, and STARs) in the system, you are much better off putting yourself there as soon as pos- sible after takeoff, and as early as possible as you approach the ter- minal area. (If you don’t carry SIDs or STARs, don’t forget to mention that fact in the Remarks block of your flight plan. It’s the best way to let ATC know of your limitations.)
When a SID isn’t published, plan your departure by the most di- rect route that will get you to a VOR or an airway as soon as possible after takeoff. The outstanding advantage of choosing an airway, direct route, or VOR radial to start your flight is that of definition; you know exactly which way to go in the absence of ATC instructions or if your radios quit before you can receive further clearance.
Radar control on departure is the name of the game in IFR flying to- day. At most terminals, you will be picked up on radar almost immedi- ately after takeoff, and the controller will vector you around other traffic and on course just as expeditiously as possible. If you’re not at all sure of the best way to get from the airport into the enroute structure, there’s one more way you can get help; request radar vectors to the first VOR on your route, and Departure Control will lead you by the hand.
There are parts of the country that just don’t have any airways headed in the direction you want to go or don’t connect the particu- lar points A and B you had in mind. So why not devise your own route, direct from one VOR to the next on your intended line of flight ? There are no rules against flying direct (off airways), but there are several very important limitations you must consider before under- taking such a course of action.
1. You should not file a direct IFR flight between VORs that are more than 80 miles apart (this is a low-altitude limit that is expanded to 260 miles for flights at 18,000 feet and above). Designed for frequency protection, the 80-mile minimum guarantees that you will not pick up a signal from another VOR station on the same frequency. 2. You must choose a flight altitude that will provide the same obstruction clearance that is automatically taken care of by airway MEAs and MOCAs. You may have to consult sectional or WAC charts or other topographic references to be sure that your off-airways route is high enough.
3. Your course must be direct —in a straight line between VORs —no doglegs on this trip!
4. You'll not receive an IFR clearance for a route that goes beyond or below ATC's radar coverage.
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Filing direct takes on new and wondrous significance when you’re flying an airplane equipped with approved Loran or GPS. Now you can file from airport to airport and expect to be cleared that way. There are times when traffic volume or other ATC problems won’t permit you to fly on such a long leash, but it’s always worth a try. And if the first controller you talk to comes up with an airways clearance, ask again to go direct when you’re handed off. Loran or GPS direct works nine times out of ten. (See Chap. 10, Area Navigation, for more details.)
In summary, you should consider the following order of routing priorities when planning an IFR flight (disregarding deviations for weather or other limitations and the availability of Loran or GPS):
1. The preferred route between departure and destination. 2. Victor airways that work out closest to a straight line between
here and there.
3. A direct, off-airways route at an altitude high enough to provide comfortable clearance from terrain and obstructions (1000 feet above everything 4 miles either side of your course in the flatlands, 2000 feet in those parts of the country that qualify as mountainous).
Altitude
Many pilots pay surprisingly little attention to the selection of an IFR altitude, even though it plays a huge part in putting the most miles behind you for the fewest dollars or making the difference between a miserable experience and an aesthetic adventure. Of course, there are some practical limits, like the Minimum Enroute Altitude (MEA), availability of oxygen, and the optimum performance altitude for your plane; turbulence, icing, wind, and weather problems cannot be ignored, but they’ll be thoroughly hashed out later.
MEAs and optimum performance altitude provide the absolute floor and probable ceiling for a nonsupercharged airplane. You can’t plan an IFR flight at less than MEA, and unless there’s a real whopper of a tailwind, you will probably lose money by climbing above your airplane’s optimum altitude. (This is usually the highest altitude at which the engine can maintain 65 percent of its rated horsepower.) Check the route for the highest MEA— that will even- tually become your cruise altitude. Although you can file (and be cleared at) a lower altitude before you get to that particular airway segment, ATC will move you up to the MEA at the appropriate
Chapter Six
time, so plan on it. The abnormally high MEAs will occur over the mountains, because they must provide 2000 feet of obstacle clear- ance in those areas.
For normally aspirated (nonsupercharged) engines, it sometimes comes down to a choice between less performance at high altitude or a much longer route to avoid the higher levels. There’s almost al- ways a westerly wind at altitude, so clawing your way up to 12,000 or 13,000 feet in an airplane with an optimum altitude of 7000 is not necessarily a bad move if you’re eastbound; the extra groundspeed on a long trip may more than make up for the time spent in the climb. There’s only one way to decide, and that’s to dig out a computer and compare the estimated time enroute for the high altitude versus a lower one. (A friend was proceeding eastbound in his nonturbo Bonanza a while back, taking full advantage of the tailwind at FL210. An airline captain overheard one of his position reports and inquired, “What’s a Bonanza doing at 21,000 feet ?” My friend answered with aplomb, “Struggling!”)
In general, when weather conditions are not a factor, it is usually better to file as high as practical, at or above the appropriate MEA, and at or above your airplane’s optimum altitude. The benefits that accrue to high flight often overcome the extra minutes spent climb- ing, and maybe it will put you above an icing level, keep you out of turbulence, or treat you to groundspeeds you can brag about at the bar. And if nothing else, why not climb up above the choking brown gunk that is the rule rather than the exception over our country these days? Why not climb up into the only place left where you can see forever and, at least for a little while, treat your lungs to some really clean air?
There’s also something to be said for the safety aspects of flying high. The very fact that fewer pilots use the higher levels means that there will be fewer people to run into at altitude; and given the usual situation of being in the clear (or at least between cloud layers) when you’re operating in the upper reaches of the sky, you’ll have more time to observe and react to other air traffic.
At any rate, give “high flight” a try on your next few trips and de- cide for yourself. Keep records of how much time is required to climb, how much fuel is burned, and the difference in elapsed times for similar wind and weather conditions at lower altitudes. Then compare the hard facts with your memories of the smooth, crystal- clear air up there; remember the pleasant glow you experienced when that first-time passenger became a believer after flying high with you.
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