Only a massive reserve of excess thrust will get you out of severe wind shear — and sometimes that’s not enough. In writing my last article on wind shear and inertia, I was reminded of the chilling tale of Delta Airlines Flight 191.

Delta 191 was a landmark aviation accident that shook the industry. Flight 191 proceeded much like any other airline flight, right up until the last 40 seconds.

First Officer Rudy Price was at the controls with the assistance of Captain Ed Connors and Second Officer Nick Nassick. The first sign of trouble came at 800 feet AGL while on final approach into Dallas Fort Worth with a 24 knot increasing-performance wind shear.

The crew rightly anticipated a loss of performance and pushed the trust levers “way up” as the airspeed dropped from 173 knots to 133 – a 40 knot wind shear. Despite the L-1011′s nearly 160,000 pounds of thrust, the aircraft still slowed to 119 knots and rapidly descended to the ground where it bounced and skidded into water tanks killing 134 passengers and one nearby motorist.

After the investigation, the NTSB concluded that Delta Flight 191 had entered a microburst. The probable cause faulted the crew for their decision to continue the approach into a cumulonimbus cloud with visible lightning and the airline for lack of specific training and procedures for avoiding and escaping low level wind shear. The NTSB also indicated the lack of real-time wind shear hazard information as another probable cause.

Despite the lack of training cited by the NTSB, this crew really did a great job. There isn’t much to wind shear escape other than applying max thrust and pitching for best climb. That’s probably going to be Vx for your aircraft unless the manufacturer or company training program specifies something else. The chilling truth about Delta Flight 191 is that sometimes you just don’t have enough power to get out of it – and that’s not a comforting thought. As with most weather-related issues, the best strategy is avoidance.

Suppose you are the captain of a Boeing 747 or Airbus A380. You’ve just received a report of wind shear from the Cessna 152 you’re following on final. Should you expect less, similar, or more wind shear?

Before you answer, be sure to consider inertia.

This one harkens back to my last post on inertia and turbulence. Here’s a no-brainer: a 747 is a lot heavier than a Cessna 152. In fact, a Boeing 747-400 at max gross landing weight is about 390 times heavier than a C-152 at it’s max gross! That means the big airplane has a whole lot more inertia, making it more resistant to changes in motion.

Remember last time, we got technical and found the somewhat obvious result that heavy airplanes give a much smoother ride through turbulence. But because of inertia, the opposite is true for wind shear! That’s right, the flying pilot on an A380 had better be careful when a lighter airplane reports wind shear (and had better taxi carefully when CRJ’s are around, but that’s another story).

I know it seems counterintuitive at first, but think about it in terms of inertia. When an airplane experiences wind shear, the shear is actually an external force acting upon the aircraft to change it’s motion.

A light plane has less inertia, and is much more likely to be pushed by the wind. The light airplane’s motion relative to the ground  actually changes with the wind shear. Consider this in terms of groundspeed: when showing a groundspeed of 60 knots, the airplane will rapidly accelerate to say, 70 knots groundspeed upon entering a 10 knot wind shear. Pilots are likely to experience this as more of a turbulent bump along with a momentary fluctuation in indicated airspeed.

Heavy metal pilots are in for something completely different. These airplanes have so much mass and inertia that they are barely affected by the external force of wind shear. If the airplane is showing a groundspeed of 200 knots, the groundspeed will show little to no change, even with a large shear of say, 20 knots. Our 747 continues to move at the same rate and direction of travel, but experiences a large and rapid change in indicated airspeed.

Left on it’s own, the airplane will gradually accelerate back to it’s equilibrium speed without crew action, so long as it doesn’t lose too much airspeed or altitude. Fortunately for the flying public, modern airline crews have specific wind shear training and an enormous amount of excess thrust at their disposal, greatly reducing the dangers of wind shear to the flying public.

In writing this article, I don’t intend to give the GA pilot false confidence. Wind shear can be serious business for all airplanes and the best strategy is to avoid it. Yes, your airplane’s lack of inertia will dampen wind shear encounters, but only a massive reserve of excess thrust is going to get you out of severe wind shear encounters — and sometimes that’s not enough.

There has been a lot of talk about the “point and wait” trick for cloud clearance since my first post on the subject. To clear up any questions on the matter, I went up and shot some video of this rule of thumb in action. Check it out and spread the word.

It’s a good idea to avoid the clouds as much as possible. For IFR pilots, you’ll typically find a smoother ride in the clear. VFR pilots have no choice on the matter: per cloud-clearance rules, it’s the law! But what about that cloud out on the horizon? You don’t need a Sporty’s sight-level to tell if you’re going to hit that puffy cumulus up ahead. All you need is a finger!

Point at the top of the cloud.

Step 1: Point
Take your pointer finger and literally point at the top of the cloud. Reach forward and physically touch the window at the top of the cloud.

Step 2: Wait
Keep your head and finger in the same position while maintaining unaccelerated flight: straight & level or steady & stabilized climb or descent.

Step 3: Observe
Observe the cloud’s motion relative to your finger.
If the cloud appears to move below your finger, you will pass above the cloud. But if the cloud moves above the finger, you can expect to go IMC in a few moments.

If cloud moves below your finger you will pass above.

If cloud moves above finger, you'll fly into the cloud.

This whole trick is based on the old collision-avoidance rule that any airplane with no apparent motion must be on a collision course. It’s easy to “eyeball” another airplane and detect relative motion.. Because of the slower closure rates and enormous size of some clouds, it is a lot more difficult to judge motion.

If you don’t mind writing on the windows, you can also use a dry-erase marker to free up your hand.

Pilots have some sort of machismo complex when it comes to making a smooth landing. I know it feels good to grease it right on the money. Not to mention that the landing leaves a lasting impression on each and every passenger. But a smooth landing is secondary to the primary goal of landing the airplane safely. Gusty winds and high crosswind components can quickly turn a beautiful flare into a scary situation. Best to err on the conservative side: just plant it! 

Sideloads are put on the airplane by landing in a crab (sideways). Pilots are trained to correct for this by entering a slip and landing one wheel at a time. The problem is that many airplanes start to get squirley on roundout in a crosswind. Control pressures are constantly changing, and the wind can quickly become too much to handle. You suddenly find yourself being blown sideways across the runway, which increases the chances of landing with a high sideload, or worse: getting blown into the ditch!

You can work to prevent a dangerous situation by doing your best to get the airplane down. Don’t try to make it pretty, just stick the airplane on the ground and accept a harder-than-normal landing. Don’t misunderstand me, I’m not telling you to fly nose-first into the runway. That would be a bad thing. Just don’t “milk it” and aim for that satisfying “chirp-chirp” of the mains in a blustery wind.

Summer is upon us and with it comes the inevitable thunderstorm. This is especially true in the Southeast where the forecast for “vicinity thunderstorms” dominates nearly every TAF. Thunderstorms don’t always have to spell out a cancelled flight, but proper thunderstorm avoidance requires a heightened level of awareness from us as pilots.

That being said, we can’t let a little thing like scattered thunderstorms cancel our plans all the time. Scattered cumulonimbus clouds tend to be few and far apart, making it easy pilots to pick their way around the weather. There are two schools of thought on this.

Rainshafts and virga extend from a dissipating thunderstorm

A lot of VFR pilots prefer to stay down low and avoid the rain shafts by a healthy margin. Although this method does work, it has its drawbacks. First off, it’s mighty bumpy down low with all that convective activity going on. Furthermore, a thick haze layer could obstruct your vision just enough to lure you into the weather. Flying around under the clouds with increasing weather can even tempt the most disciplined pilot into scud-running, which is always a bad idea.

Perhaps the best way to dodge weather is to get on top and visually weave your aircraft around the buildups. After flying a variety of aircraft with anything from onboard radar to XM satellite weather, I can personally vouch for Richard L. Collins’ statement that the best weather avoidance tools are your own eyes, or the “Mark II Eyeball,” as he calls it.

My eyeballs tell me I don't want to fly through that.

Visually dodging works great, but piston driven (and even turboprop) aircraft can’t always stay out of the muck. That’s right, the instrument rated pilot might find himself blindly flying towards embedded thunderstorms! Without onboard weather radar, this is a very dicey proposition and serious thought should be given to landing and reevaluating your options.

If you are continuing (are you sure this is such a good idea?) then it would be prudent to make full use of air traffic control and local flight service stations. You might be blind, but the controllers and FSS personnel may be able to suggest alternate routing that will keep you out of the worst of it. Sure, there are no guarantees, but it’s better than nothing.

The darker areas will usually have more severe turbulence.

Even in the clouds, the window can play a role in thunderstorm avoidance. Near nasty weather, it is not uncommon to see gradients of white and grey in the windshield. As a rule of thumb, avoid the dark patches for the smoothest ride and don’t ask, but tell the controllers what you need in terms of heading and altitude.

Thunderstorms are serious business, and ought to be avoided at all costs. This doesn’t mean that you can’t fly, but it does mean that you have to be careful. Visual avoidance is always your best bet, and the decision to enter a region of thunderstorms in IMC needs to be well thought out. Use all available resources to plan and reevaluate your flight, and know that there is no shame in landing and waiting out the storm.

A lot of VFR pilots talk about punching through holes in the cloud deck and flying on top. This usually raises a few eyebrows, and brings up a few questions. Is this legal? And more importantly, is it safe?

To answer the first question, yes it is perfectly legal to fly VFR above a cloud layer. In fact VFR over the top has a specific FAA definition under 14 CFR 1.1:

VFR over the top, with respect to the operation of aircraft, means the operation of an aircraft over the top under VFR when it is not being operated on an IFR flight plan.

A lot of pilots prefer to fly cross country on top to avoid low-level turbulence which usually stops above the bases of cumulus clouds. Keep in mind that VFR flight visibility and cloud clearance rules still apply, so you can’t get too close to those clouds.

Is it safe?

This is a difficult question to answer, and it depends on the pilot’s individual experience and decision making skills.

As a VFR pilot, flight on top presents a variety of new hazards. Without reference to ground landmarks, a pilot must maintain a higher level of situational awareness through onboard navigational aids. It’s easy to get lost up there.

Cloudscapes can be a hazard of their own. VFR pilots are trained to fly the airplane primarily by reference to the horizon. Sloping cloud layers can create false horizons which may lure the pilot into a descending turn. The attitude indicator and heading indicator will be your best bet to notice and rectify the situation.

Perhaps the greatest hazard is that of getting stuck on top. There is no guarantee that the hole you climbed through is going to be there when you want to come back down. Pilots need to monitor the weather and get back down before the broken layer becomes an overcast.

Flying VFR on top is as safe as you can to make it. If you’re new to the game, then might I suggest that you stay below the deck for a while. For those of you going up top, keep your guard up and fly safe!

Several years ago, NASA produced a video for pilots detailing their research in tailplane icing and tailplane stalls. Produced by the Imagine Technology Center at NASA’s Lewis Research Center, the video describes signs indicative to the onset of a tailplane stall, aerodynamics and recovery techniques. The video was produced as a result of insights gained from the NASA/FAA Tailplane Icing Program.

We’ve all been there. The weather is marginal and you are faced with the infamous go/no-go decision. Many questions go through your mind. How accurate are those forecasts? Has the weather already begun to improve, or is it getting worse. Can I climb above that cloud layer? These and many more can be answered by a PIREP. In this article, you will see how easy it is to submit your own PIREP.

A PIREP is a pilot report of actual weather conditions encountered by an aircraft in flight. PIREPs are usually transmitted by radio and encoded as a block of text describing the location, time, altitude, aircraft type, and weather phenomenon observed.

Unfortunately, PIREPs tend to be few and far between. For example, as of the time of writing, I count a total of seven PIREPS in the Southeast United States, and that is with an advancing cold front and rain showers blanketing the area. You can improve the aviation weather reporting system by submitting your own PIREP next time you fly.

So how do you submit a PIREP? It’s actually a very simple process. Begin by contacting the nearest flight service station (FSS) and tell them that you would like to submit a PIREP. Now, report the following items:

1. Location relative to a VOR or airport
2. Altitude of your aircraft
3. Type of aircraft
4. Time of the weather observation (example: “five minutes ago,” or “1655 Zulu”)
5. One or more weather observations (example: “cloud tops 4,000,” or “continuous light chop,” or even “OAT 04 degrees”)

A simple pilot report might sound a bit like this:

You: “Atlanta Radio, Cessna 12345 monitoring 122.2″
FSS: “Go ahead Cessna 12345.”
You: “Cessna 12345, We’d like to submit a PIREP.”
FSS: “Ready to copy Cessna 12345.”
You: “Cessna 12345, over two-five east of ABC at four thousand five hundred feet, type C182, time 1655 Zulu, cloud tops at four thousand.”
FSS: “Thank you Cessna 12345.”

To make PIREPs even easier to report, AOPA has put together a great form that you can print out and fill out in flight before you contact the flight service station. To become a certified expert on PIREPs, take the Air Safety Foundation’s SkySpotter mini-course.

Sometimes it pays to pull the power back and take your time. In fact, sometimes it can save an awful lot of time.

I was operating a flight from Chattanooga to Memphis on a foggy winter day. I had been flying this trip all month, and the flight had become quite routine. Today, the weather put a slight kink in our plans. The latest forecast read as follows:

TAF KMEM 300530Z 3006/3106 29005KT 2SM BR SCT001
      TEMPO 3006/3010 1/4SM FZFG VV001
     FM301000 29005KT 1SM BR SCT001
      TEMPO 3010/3013 1/4SM FZFG VV001
     FM301500 27010KT P6SM BKN100
     FM302000 25010KT P6SM SCT050 BKN100
     FM310000 30005KT P6SM BKN050

We were scheduled to arrive in Memphis at 13:30 Zulu time. Our minimums for shooting a Category 2 ILS approach required a runway visual range (RVR) of 1,600 feet, or about 1/4 statute miles visibility. The latest METAR from Memphis revealed an RVR of 1,200 feet, well below our minimums. Although the weather was forecast to improve, we had reason to suspect the timeliness of that improvement. There was still a good chance that we would wind up at one of our alternates. Not cool.

It was my leg to fly and my captain made the insightful suggestion to fly slowly. Although we were in a hurry to get back, I agreed that this was the best course of action and kept the speed down, and that made all the difference.

By maintaining a lower cruise speed, we improved the safety of flight and shaved hours off the trip. How is this possible you ask? Read on.

For starters, a lower cruise speed resulted in a much more efficient fuel burn, allowing us to arrive with a few hundred pounds of extra fuel. Had the weather not been conducive to an approach, the extra fuel could have bought us a little more time to wait and see if the visibility would cooperate before diverting to an alternate.

We also reasoned that the slower cruising speed would also allow us to arrive a few minutes later, well into the time period in which the visibility was forecast to improve. En route, Memphis’ ATIS revealed an RVR of 1,200 feet, which gradually improved to 1,800 feet just prior to our approach. We were legal to land.

At no point did we have to enter a holding pattern, and we landed uneventfully on 36-Left after a textbook approach right down to minimums.

If we had made a speedy dash to Memphis, we might not have been legal to shoot the approach, and our passengers would have experienced an unpleasant delay in Huntsville complete with missed connections and frayed nerves. Instead, we took our time and completed the flight just a few minutes late, as opposed to a few hours for the would-be diversion.

Don’t let get-there-itis trick you into rushing towards the sky. If the weather at your destination is uncooperative, but scheduled to improve, it may be prudent slow down. In some cases, it might even be wise to delay your departure until the weather begins to clear. With a little patience, you can beat the weather and find your runway well above minimums.