The Other Part of Flight Planning

There is probably no aspect of aviation that has been talked and written about more, and practiced less, than flight planning. I wrote a book on flight planning myself; it was the slowest selling book I ever wrote.

Most general aviation pilots flight plan by filling up the tanks, estimating airspeed and fuel flow with basic “rules of thumb”—“I figure I cruise at 130 knots and burn 10 gallons an hour”—and select an altitude based on how high they have to go to get smooth air. Departure airport is a given, destination whichever airport is closest to the final destination—what’s the point of having an airplane if you end up having to drive further than you want to?—and alternates are something they don’t think about too much because they seldom need them and if they do there are usually a bunch to choose from, all within comfortable range since they started with full tanks and don’t usually fly all that far on any one leg anyway. If the weather looks like they have to file IFR, they pick a route that they would like to get—you never know, you might get it and you sure won’t if you don’t ask, and anyway, if maybe enough people keep filing for a route that makes sense instead of the stupid routes ATC usually gives you, maybe they might someday get the message. And for most pilots most of the time, this so called “flight planning” works. Most of the time.

The problem isn’t that it isn’t really flight planning—it is flight planning of a very rough and inefficient sort. The problem is that it doesn’t tell you anything about how the flight is actually going—it just assumes that it is going well. The only back up is a bunch of fuel, but without a clear cut plan of action, that bunch of fuel can not only disappear quickly, it can lead you to all kinds of trouble, flailing about trying to figure out what to do when Plan A didn’t work.

I’m not just picking on non-professional pilots here either when I say general aviation pilots: when I flew corporate Citations and Falcons we did exactly the same thing: filled the tanks, filed for a standard airspeed and altitude, estimated range based on rules of thumb for airspeed and fuel burns, and launched. We didn’t always fill the tanks when away from base, where it cost more, but we still put plenty on: you know, the old,”… except when you’re on fire” cliché. But the airlines do it differently, and I think there is a lot to be learned from the differences, and I think it is a big factor in explaining their much lower incident and accident rate compared to general aviation.

There are really two parts to flight planning: one, flight planning, and two, planning the flight. Sounds like the same thing, but the first part pertains to the flight from takeoff to touchdown, and the second part answers the question, “What sort of flight are you planning?” Every pilot who has ever passed a private pilot written test or done a dual cross country flight knows what flight planning is: plot a true course, convert it to magnetic, adjust for winds and compass deviation, estimate true airspeed and fuel flow, establish check points, make up a flight log, etc. But they seldom think about the second part because it seems like a given: I’m going to fly from here to there; what’s there to plan?

In terms of the departure airport, there isn’t much to plan: short of taking the wings off and trucking the aircraft to another airport, the departure point is determined by the aircraft location. (But if you rent, presumably you do have some choices there, and the most suitable departure airport then becomes a factor.) But whether you file IFR or VFR, your choice of destination airport, and your alternate airport selections, are big factors in safe and reliable flight planning—the “planning the flight” part.

Let’s look at the IFR versus VFR choice first. Obviously, if you’re not instrument rated or current, you have no choice here, but let’s assume you are (and if you’re not, start working on it right now). Most instrument rated pilots only have the rating to “keep themselves out of trouble,” meaning, so they can fly in the clouds legally if they have to. It isn’t something they want to use or like to use, it’s there just in case they need it, but the fun part is flying VFR.

The problem with that is that the only way to stay proficient in instrument techniques is to file an IFR flight plan and fly IFR all the time, regardless of conditions. If you always fly on an IFR flight plan, it will become second nature to sometimes fly in the clouds and sometimes not, to sometimes shoot a full instrument approach and other times do a visual approach. But if you only have the rating for the times you have to use it, how comfortable are you going to be in those clouds or on instruments on approach when it isn’t something you normally do? The simple truth is, if you aren’t comfortable filing IFR on VFR days, how comfortable are you going to be filing IFR on IFR days?

I know all the arguments for not filing IFR and none of them hold any water—they’re just excuses, really. But I’m not going to try to argue you out of not filing IFR all the time, because if you don’t want to hear it you won’t hear it. Just remember what I said and think about it.

So let’s assume you have decided to file IFR. The next question is, from where to where? Departure is normally a given, but the destination is not—there are almost always a variety of destination airports to chose from in the vicinity of your final destination. Some will be closer, some will have cheaper gas, some will have full service FBOs, some will have multiple runways, some may have long runways, some will have only non-precision approaches and some may have precision approaches, either ILS or LPV (localizer performance with vertical guidance, which requires approved GPS or DME/DME equipment), and a few may even have precision approach guidance to multiple runways. So how do you chose? Easy, chose the best one. If you’re talking about making your flights simple, easy, reliable, uneventful and routine, you go to the airport that has the most of everything: the longest runways, at least one precision approach to standard minimums (200 & 1/2), a full service FBO, operating control tower during the expected time of arrival, approach and departure control, the full works. I know the folks at the local grass roots airports can be very friendly and helpful and need the business, I know I don’t have to have a long runway, I know that most of the time the weather will let me get in with a non-precision approach or maybe even a contact approach, and I know I would really prefer to be as close to my final destination as I can get, but what I also know is that, when I take off, I want to have everything going in my favor to complete the flight safely and routinely.

Why not file to the close-in airport, the one without long runways and precision approaches, take a look, and if it doesn’t look good, then go to the big one? Sounds reasonable, but it isn’t just about whether the weather cooperates and lets you sneak in, it’s also about all the other little “surprises” the less than fully capable airports have in store: obstructions, narrow runways with soft shoulders, non-standard patterns, minimal lighting, poor taxiways. (As a young Part 135 pilot I once took a Cherokee 6 down a road I thought was a taxiway, tried to get back to the taxiway by cutting across the grass and dinged the prop when the nose wheel went into a ditch. The boss let me drive the prop to the prop shop for repair, on my time, as part of my “education”.) Even if you’re very familiar with the airport and don’t expect to be taken by surprise, why take any unnecessary risks when you have another nearby airport with a nice big long wide runway with a full approach light system and an ILS that will take you right down to within ½ mile of that runway, 200 feet over the approach lights, virtually guaranteeing a safe arrival?

There’s another reason not to follow this strategy, this “take a look” approach, and that is that it is human nature to want to make it work out once you’re there, to do more than just “take a look” because you don’t want to have admit that you would have been better off to just go to the big airport in the first place, so you fudge a little bit on the MDA, or maybe you do a little bit of scud running, diving through a hole because you know once you get underneath it will be “right there”, or you go back and try the approach again because you caught a couple of glimpses of the runway as you went around and you know you have a good chance of making it the next time, or you try a different approach because, “It looked like the weather was breaking up at the other end,” and so on. Those are just not safe, routine arrivals.

So you filed IFR to the best airport in the area, you shot an ILS approach to minimums, a good approach, but the “runway or runway environment” just wasn’t there, or there were thunderstorms in the vicinity, or freezing rain, or snow flurries, or a truck hit a regional jet and closed the main runway, or for whatever reason you weren’t able to land at your preferred destination. Now what?

You aren’t always required to have an alternate; if weather reports and forecasts indicate that, “For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles” [FAR 91.167], an alternate is not required. What’s the significance of this? Fuel. An alternate airport requirement means you have to have enough fuel to fly from your destination to the alternate airport, so more fuel is required. This is almost never a problem for general aviation aircraft because they usually have a lot more fuel capacity than is ever really needed. And anyway, who would want to take off on an IFR flight plan with only 45 minutes more fuel than needed just because the destination was forecast to be just a little bit better than basic VFR minimums (3 miles and 2000 feet)? So the question isn’t, “Do you need an alternate airport?” but, “How do you select one?”

Under Part 121, the part under which the airlines operate, a flight cannot be release unless both the Pilot in command and a certified dispatcher have agreed on the flight plan. Discussion and negotiation are allowed, but eventually you have to agree on a plan. I used to have more disagreements with dispatchers over alternate airports than any other part of the dispatch release, because fuel planning (i.e. fuel conservation) is a big part of the dispatcher’s job, and the selection of an alternate airport determined the amount of extra fuel required, a nearby alternate requiring less extra fuel, a faraway alternate more. So dispatchers, who aren’t bad people, mind you, but they have their job and I had mine, almost always look for the closest alternate, in order to save fuel. (You sometimes wouldn’t know it, but airlines are in business to make money.) But I was the one who had to actually go there if I couldn’t get in to my original destination, and I sure didn’t want to have a problem getting into the alternate as well. If it came to diverting, I wanted to be sure it was going to be a big non event, and not more of the same only now with that much less fuel.

For example, on flights from DTW to LAS, the dispatchers would almost always select LSV, Nellis Airbase, just a few miles from LAS on the north side of town, for an alternate. If the weather went down at LAS, thunderstorms for instance, then Nellis would probably also be affected. So it really wasn’t a very good alternate, but it was close, and if thunderstorms weren’t forecast it would be legal and the dispatcher didn’t have to allow for very much extra fuel. So I would call and say I wanted a more distant alternate, LAX, for instance, and they would usually agree and give me a revised release with a little more fuel, or if they gave me a hard time I’d just put the extra fuel on, knowing I could get to LAX if I had to. Another time I was going somewhere in the Caribbean, St. Martin I think, and the dispatcher gave me some little island airport I had never heard of for an alternate, it had one runway, a non-precision approach, and was listed as a Special Airport, meaning there was something unusual enough about it to require an airport briefing or prior experience, but it was nearby. I called and got quite of bit of resistance, the dispatcher telling me that it was all legal and the weather was good in St. Martin anyway and what was the problem? I said the problem is, this is the Caribbean, where anything can go wrong, single airport runways get closed because of damaged aircraft, thunderstorms roll in unexpectedly, radars go down, power fails, five aircraft arrive at once and four have to hold, all kinds of things that lead to diversions, and when that happens I don’t want to have to go to another airport with only one runway, a non-precision approach, no radar, and special approach restrictions. So I got a better alternate, probably San Juan, and no, I didn’t need it, but I sure was glad to have it and to not have to worry all the way to St. Martin about it.

Under Part 91 you don’t have to have a dispatcher sign off on your flight plans, so you can pick any alternate you want, even none at all if the destination weather is good enough. And because of that it often doesn’t get much thought, just a quick check to make sure there are some other airports with decent weather forecast nearby, the assumption being you probably won’t need it anyway and if you do you’ll deal with the weather that actually exists at that time, real reports, not forecasts, so you’re good to go. And that is absolutely not the way to do it, for all kinds of reasons, but the main one is if you are shut out at your destination for any reason—weather, runway closures, security threats, lost pilots in the vicinity—you don’t want to have to figure out what to do at that point, you want to already know what you’re going to do and then just do it. Before you left you should have said, “I’m going to fly from this airport to that airport, and if that doesn’t work out I’m going to fly to this other airport, an airport that has several runways, several approaches including an ILS, approach radar, excellent weather forecast, and I’m going to land there, and that is that. Not that it can’t be changed if needed: if you get to your destination, and can’t land, and you advise ATC that you want to go to your alternate, and they tell you it isn’t available for some reason, or it is but the ILS is out of service and the weather is marginal, or you head that way and check the weather, and the same weather that shut you out at your destination is headed that way also, of course you can ask ATC to check the conditions for you at other airports nearby and change your alternate. But changing your alternate is a lot different than not really having one in the first place, or having to pick one quickly after having just done a missed approach because a snow flurry hit the field and visibility dropped to zero.

So let me summarize how I think you should plan a flight: Choose a destination airport that is the best you can find within a practical distance from your final destination; select an even better airport for your alternate, one with excellent approach and landing facilities and good weather, one that virtually assures a safe arrival; fly to your destination; if that doesn’t work out, go to your alternate and land. That’s the easy way to plan a flight, and the best way I know to make sure your flight ends up with everyone walking away happy.