Weather Matters

 

 

I got a request the other day from someone who wanted to use one of my articles in his online aviation course on computer flight planning. His business is called www.PilotWeatherTraining.com,  and I checked it out and it got me thinking about weather.  I haven’t tackled aviation weather since I was writing full time back in the mid 80’s, and with another 10,000 hours of so of experience since then,  I thought it might be time to think about it again. Specifically, what kind of weather matters, and what doesn’t?

First, what do we mean by the word “weather”? Weather is atmospheric conditions. A severe clear day with no wind is still weather.  But in aviation, when we talk about “weather”, we mean the stuff that can adversely affect our flight.  If the skies were never any worse than scattered clouds, visibility greater than 10 miles and winds under 10 miles per hour, we really wouldn’t ever need to worry much about the weather—it’s always a “go”. But that’s not the case, not even in the relatively dry southwestern states (US), so weather is something we have to take into account.

For the VFR only pilot, “weather” is not so much a question of avoiding the stuff that can really hurt you as it is having adequate visibility to navigate and avoid terrain and obstacles.  Of course the VFR pilot wants to avoid freezing rain and thunderstorms and heavy turbulence, but that should largely take care of itself if he or she has adequate visibility in the first place. So what is “adequate”? “It depends” is always a safe answer but doesn’t get us very far.  The normal VFR visibility minimums of 3 miles might be adequate, or it might not be.  The VFR only pilot flying a Champ at 80 mph on a very hazy summer day on a very short trip over terrain he or she is totally familiar with can probably call 3 miles visibility adequate.  Another pilot flying a Piper Arrow or a Cessna 182 on a longer trip over unfamiliar terrain would be asking for trouble in those conditions.  So visibility depends a lot on speed and familiarity with the terrain.

What about clouds? VFR minimums say you must be at least 500 feet under any clouds, 2000 feet away from any clouds, and at least 1000 above any cloud.  It’s okay to fly between them and it’s okay to fly over them as long as you stay that far away from them.  (This is to provide some reaction time in case an aircraft, one presumably operating under Instrument Flight Rules, comes popping out of one of those clouds.) So I guess that means that as long as we are willing to stay under the clouds, we could fly even with overcast skies.  And for short trips that probably is okay.  The problem with overcast skies is that the ceiling almost always gets lower as you approach the system that is causing the overcast.  If you are flying away from that system, toward higher ceilings and eventually broken, then scattered clouds, fine.  Otherwise, you better not be going far because you’re going to find yourself having to go lower and lower to stay under the overcast, and down that road lies trouble.

The real problem with VFR only flying is its intended purpose: If you intend to fly VFR for transportation you are going to run into problems; if you intend to fly VFR for pleasure, you are probably going to have a ball.  (See numerous previous posts on “Oshkosh”—Air Adventure—to get an idea of how much fun flying for fun can be.)  And the reason is quite simple, even if it is still quite hard to accept: flying for transportation, that  is, flying at a given time to a specific place over a given distance and course, requires tools to deal with the realities of weather, and VFR only flying doesn’t have those tools.

The only way to consistently and reliably fly for transportation is under Instrument Flight Rules with an appropriately equipped aircraft and by a suitably qualified and current instrument rated pilot.  That takes care of the visibility limitations of VFR only flying, and it takes the risk out of flying on top of broken clouds or overcast skies, but now the problem of avoiding hazardous weather doesn’t take care of itself.  So what are those hazards, and what can we do to avoid them?

I like to think of hazardous weather as any weather I don’t ever want to encounter in any aircraft.  The L-1011 was a fabulous aircraft, I think the best air transport ever made. (Certainly newer aircraft have better systems and are more efficient, but manufacturers have discovered that aircraft don’t have to be the best that can be made, just good enough.)  As good as it was, I still wouldn’t want to take it into thunderstorms, or  severe turbulence, nor would I want to take it through heavy icing, hail, or freezing rain on takeoff, approach or landing. There are limits to the stresses any aircraft can take, and there are limits to the amount of ice it can carry and damage it can sustain. General aviation aircraft are normally certified to greater G limits than transport category aircraft, but I still wouldn’t want to take any aircraft into a thunderstorm or heavy turbulence.  (That includes an F-16 stressed to plus 10 G’s, not that I’m going to get a chance to try.)

The L-1011 had every kind of anti-icing equipment imaginable, of course, and it also had something else—it could climb rapidly through the lower altitudes where serious icing is normally found up to the flight levels where the temps are so cold that icing is seldom found. Anti icing for turbofan aircraft is mostly  a matter of keeping the engine cowling clear and the pitot/static system heated.  General aviation aircraft are different, not just because they spend a lot of time at altitudes where icing occurs, but because it affects them differently.  It is fairly easy to protect a propeller driven, reciprocating engine from ice: you need “hot “ props and an alternate air source. But keeping the aerodynamic surfaces clean—the wing, the tail, the rudder—that is a different matter.  In some 12000 hours of flying jets, I can count on one hand the number of times I had to use wing deicing.  In some 2000 hours flying general aviation aircraft, I can’t count the number of times I had to use wing deice—“the boots”—and I do remember many times when they didn’t work very well. Approval for flight in known icing is great, but only to get you out of it if you happen to fly into it.  General aviation aircraft should avoid any icing conditions and, if encountered anyway, get out of them as soon as they can. 

The L-1011 also had an incredible radar, with a bunch of power and a great big antenna up in the nose, and I learned from experience to trust it and  to rely on it: If it showed a red area inside a cloud, you could bet your 401(k) that that cloud was a thunderstorm.  If it showed mostly green areas of precip with a few smaller areas of yellow (heavier rain), you could feel safe entering, avoiding the yellow areas. Radar in general aviation aircraft aren't nearly as powerful or as sensitive and can’t be relied on for weather penetration.  They should be used to avoid areas that might contain thunderstorms.  The same goes for ground based weather radar relayed to cockpit displays.  They paint a good picture, better than most aircraft radar pictures, but they are refreshed much less often than aircraft radar, so they aren’t real time.  The two should be used to together, if you have both, to stay completely away from any weather that might contain thunderstorms. Remember, you don’t ever want to fly in a thunderstorm in any aircraft. One time is one too many.

One final note on avoiding thunderstorms from an “old guy” who has been there a lot: the best way to avoid thunderstorms is to flight plan away from them. I don’t care how far out of the way you have to fly, do whatever you have to do to avoid any chance of having to deal with them.  And I don’t care if it means you probably shouldn’t fly at all that day. No airplane can fly anytime under any conditions.  The less weather capability you have, the more often you will come upon those days, and the further out of the way you will have to fly on days you can, but so what? There is no trip so important that taking a chance on hazardous weather justifies it.  And please don’t be tempted to try a “look-see” under VFR.  That leads to nothing but trouble, like when you turn around and the weather has closed in behind you as well.  Just stay away from thunderstorms.

You want to stay completely away from freezing rain and hail in flight, but they are not the same kind of hazard.  Hail comes out of thunderstorms, and you shouldn’t be anywhere near them.  We went over that.  Freezing rain happens when rain falls into colder, freezing temperatures.  At the first hint of freezing rain, climb if you can.  You usually only have to go up a couple of thousand feet to climb into warmer air with rain.  If you can’t do that, turn around. Going lower almost never works, and trying it exposes you that much longer to what can quickly coat the aircraft and add hundreds of pounds of additional weight.  It isn’t worth the gamble.  Go back.

That leaves turbulence not associated with thunderstorms, and it really doesn’t matter what kind of turbulence it is—mountain wave, convective, jet steam, clear air—if the forecast or reported turbulence is severe or extreme, don’t go there.  If it is moderate, you may not want to go there—the ride will be awful and aircraft control will be a tiring, constant battle, but it won’t hurt you.  Unless it gets worse.  Turbulence of any sort is best avoided, but it’s the severe stuff that will hurt you. Again, the best way to avoid turbulence is in the preflight planning, and the only way to find out about it is with a complete weather briefing.

Actually, I tried to summarize all of these elements of safe cross country flying back when I was writing full time, first in my book Fly Like a Pro and later in Improve Your Flying Skills. The result was a mnemonic (like GUMP, for the prelanding check).  My mnemonic for preflight planning was BILAHs, pronounced “bylaws”.  That may have been a long time ago, but the basics never change. Here’s how it works:

• The B is for briefing, meaning weather briefing.  Always get a complete weather briefing for every flight outside the local area.

·         The I is for IFR.  Always file IFR, if you can, and if you can’t, either accept that your flying is going to be mostly local, or start working on it.  The reason to file IFR every time is that that is the only way to stay current and be comfortable with the ATC system.  If you aren’t comfortable filing IFR on a good day, how comfortable are you going to feel on a lousy day when you have to?

 

·         The F is for flight log.  Always make a flight log with legs, times, fuel estimates and keep it current enroute.  It is the only way to see trouble coming.
 

·         The A is for alternate: always have one, required or not, and make it a good one.  A solid gold alternate with the fuel to get there is the best “out” in aviation. (See January 2010 post, “The Other Part of Flight Planning” for more on this.)
 

·         The H is for hazardous weather.  Stay away from it.  That’s what this post is all about.
 

If you follow these simple BILAHs of cross country flying, you will eliminate 90% of the problems general aviation pilots get into. Commercial pilots don’t have any choice, they have to fly this way.  You have a choice, but do it anyway.  It’s a little more work, but in the long run it’s a lot more fun and sure beats scaring yourself to death.

Ace in the Hole

FAR Sec. 91.3

Responsibility and authority of the pilot in command.

(a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.

(b) In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.

(c) Each pilot in command who deviates from a rule under paragraph (b) of the section shall, upon request of the Administrator, send a written report of that deviation to the Administrator.

People often ask me if I had any emergencies during my flying career, and of course I did, everyone does, but there is a big difference between a simple engine failure on a lightly loaded aircraft and catastrophic failure that takes all of the hydraulics with it. I had the former, the pilots of United Airlines Flight 232 had the latter. We experienced high vibration on the center engine shortly after takeoff from Orlando enroute to Boston. I shut it down, converting our three engine L-1011 into a twin engine L-1011, circled back and landed. Except for the fact that it happened on Christmas Eve, where we spent the night, it was no big deal. The DC-10 that the crew, with the help of a check airman who happened to be onboard, managed to get on the ground in Sioux City, Iowa, after losing all hydraulic power had one of the most serious emergencies in all of aviation. So there are emergencies and then there are emergencies.

You won’t find this elaborated on in the regs, nor will you find a definition of an emergency anywhere in the regs or a list; i.e., “ The following are emergencies, everything else is not.” The reason is simple: an emergency is anything the pilot in command thinks it is. The pilot in command may be asked to explain later why he or she exercised his or her emergency authority, but the point is, “The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.” Period. If you have something that you consider to be an emergency, do whatever you have to do to resolve the matter. We’ll talk about it later, on the ground.

This means you don’t even have to “declare” an emergency. We often use the phrase, “the pilot declared an emergency,” and of course you can: “ATC, this is N1234X, smoke in the cockpit, unknown source, declaring an emergency, making a rapid descent for landing at the large airport five miles ahead.” That would be a good thing do, if you can, but “aviate, navigate, communicate” still rules. The fact the you didn’t “declare” an emergency doesn’t mean you didn’t have one. If you’re still not sure about that, reread 91.3 again. You won’t find the word “declare” there.

Back in my early days in aviation I flew for a corporation out of Lebanon, NH. The Chief Pilot and I took off one morning in a Falcon 20 and, on the climb, fairly high up, the door seal became detached creating a leak and resulting in a rapid decompression. We donned our masks, told ATC we were making a rapid descent and, once things were under control, I called ATC and told them what our intentions were (which was to descend to below 10,000 feet and return to Lebanon). When we got on the ground the tower told us to call Boston Center. All they wanted to know was, did we have an emergency? The Chief Pilot said, “Yes, we did. We may not have declared it but we did.” They said, “Fine, no problem, but since you did deviate from your clearance, we have to make sure you had an emergency.” And that was the end of that.

So does this make FAR 91.3 a “get out of jail free” card? No. It’s more like an ace in the hole. Let me try to explain. Let’s say you leave your aircraft by the fuel pumps with a standing order to top it off. Everyone working the line at the FBO thinks someone else fueled it, it gets put away with whatever fuel was remaining, and the next time you go fly you just get in and go, fail to note or disregard the fuel gauge, run out of fuel, declare an emergency and put it down in a field. You did have an emergency, and you won’t be violated for landing off field, but you will still be held accountable for careless and reckless operation because you failed to conduct an adequate preflight inspection and you were unaware of your actual fuel load. Your emergency authority won’t help you there.

So maybe it’s more like a carte blanche or a wild card: once I have an emergency I can do whatever I want. Not really. Paragraph (b) says you may deviate from any regulation “to the extent required to meet that emergency.” So there a limits. An emergency, for instance, does not justify doing what is convenient for you, like continuing on to your home airport. It allows you to land at the nearest suitable airport. After that your emergency authority runs out.

But here’s the important part that many pilots don’t fully comprehend: when bad things happen to good pilots, your emergency authority is your ace in the hole. This is a very powerful card the FAA has given you. Maybe the best way to illustrate this is with another “war story”. This one again involved an L-1011.

The trip was a charter from Newark, NJ to Oporto, Portugal. We were flight planned for one of the mid 30’s flight levels, I can’t remember exactly which one, but probably FL 330 at Mach .84. But when we picked up our Atlantic clearance we were held down to FL 280, still at Mach .84. I knew this meant we were going to be going like stink—the lower the altitude the higher the true airspeed for a constant Mach— but I also knew we would burn a lot more fuel per hour, and the net would be a negative, a higher fuel burn than planned. But we had a lot of fuel at that point, so I talked it over with the crew and we agreed to watch it closely approaching the Azores, which was on our route of flight, and if we didn’t like what the fuel remaining at destination looked like at that point we would shoot into Lajes. We had an “out.”

Approaching Lajes the estimated fuel remaining at Oporto looked good and the weather there was good, broken clouds, six miles visibility, forecast to stay that way. Estimated fuel remaining at the alternate, Lisbon, was a little bit tighter, but the weather there was even better, it was very unlikely we would ever need to go there and technically an alternate wasn’t even required anymore. So we trucked on.

That turned out to be a bad decision. The winds aloft shifted, the fuel situation got worse, and at some point I said, “We no longer have the option of doing a missed approach at Oporto and continuing on to Lisbon. Whichever airport we head to is the airport we’re going to land at.” The weather and the facilities at each were both good, and Lisbon was a little further away, so there really was no advantage to going there. So, again, we trucked on.

Arriving at Oporto, the flight engineer checked the ATIS and said, “We’re not approved for Cat III approaches, are we?” I said, “No…why?” He said, “Visibility is RVR 300 meters, ceiling indefinite. They are only approving Cat III approaches.” Oporto is right on the ocean, and a fog bank must have moved in. That visibility was well below our authorized landing minimums of 200 foot ceiling and ½ mile visibility. The L-1011 is perfectly capable of Cat III landings, its autoland system is probably the best ever made and will put you right on the centerline, right in the middle of the landing zone, on speed, every single time, and we often used it when shooting ILS approaches at or near minimums. But, due to the considerable extra expense of maintaining it to Cat III minimums, we were not authorized to use it below standard ILS minimums.

We no longer had the fuel to divert to Lisbon. We didn’t even have enough fuel to hold for awhile and hope conditions got better, which was pretty unlikely anyway. We were going to have to land at Oporto, Cat III authorized or not. And we did. The L-1011 autoland system did a perfect job—I knew it would. But it required me to exercise my emergency authority, my ace in hole, which I didn’t hesitate to do, nor should you if you find yourself in a jam.

Could I have handled this better? Absolutely. Everything I did was according to regulation and if the FAA had wanted to come after me for getting in a situation where I had to exercise my emergency authority and land below minimums they would have had a very tough time making the case. But just being legal is a fairly low standard. What I should have done, as soon as we got our clearance to cruise at FL 280 instead of FL 330, was call Stockholm Radio on HF and get a phone patch through to the company and have dispatch run another flight plan through the computer for FL 280, Mach .84, get current weather, talk to operations, and together come up with plan. It might well have been the same plan, but that help was available and I didn’t use it. Instead I took a “wait and see” approach that went sour and ultimately required me to turn over my ace.

I don’t want anyone to think for a moment that I am encouraging you to take a chances because you always have this ace in the hole to use if it doesn’t turn out alright. But I also don’t want you to make a bad situation worse because you were afraid to exercise your emergency authority. Do the best job as a pilot you possibly can, be as careful as you can, exercise good, conservative judgment , and when it still doesn’t work out, do whatever you have to do to get it on the ground. You have that authority. You’re the pilot in command.


(I want to thank my good friend Rusty Sachs, lawyer, former FAA Pilot Examiner and former head of the National Association of Flight Instructors, for reviewing this post and offering several very helpful suggestions.)