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The Thunderstorm Threat General Aviation News

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The Thunderstorm Threat

By ED BROTAK

With the onset of warmer weather, pilots face the increased risk of encountering thunderstorms.

Although more common in the warmer months, thunderstorms can occur even in the winter, especially in the southern states. It’s estimated that 100,000 thunderstorms occur in the U.S. each year. Some locations in southwest Florida have 100 storms a year, but thunderstorms do occur in all 50 states.

Thunderstorms are most common in the late afternoon, but can occur at any time of the day.

Technically called convective cells, a thunderstorm can cover an area from 200 to 1,000 square miles. Storms can range in height from 10,000 feet to over 60,000 feet. Individual cells can last from less than a half hour to many hours.

THE DIFFERENT TYPES OF THUNDERSTORMS

There are different types of thunderstorms that develop under different conditions. “Air mass thunderstorms” typically develop in the late afternoon and evening due to the heat of the day. Development tends to be random, but they are more numerous over mountainous terrain. Although relatively weak, they can still pose problems and should be avoided. Fortunately, air mass thunderstorms tend to be slow moving.

Dr. Ed Brotak

A greater threat is posed by organized convection. These are stronger storms that often move quickly, up to 60 mph. They are often associated with fronts, especially ahead of cold fronts.

“Squall lines” form when convective cells develop in a line in response to prevailing atmospheric conditions. The line can extend for tens or even hundreds of miles. Although there are breaks between the cells, circumnavigation or remaining on the ground until the line passes is strongly recommended. Individual storms will die out only to be replaced by new cells, with the whole system lasting for hours.

MINIMIZING THE DANGER

It’s a good time to review the risks thunderstorms pose to aviators and what you can do to minimize the danger.

Many things are happening inside a thunderstorm cloud (cumulonimbus) that they pose a wide variety of threats to aircraft.

Lightning can certainly do some structural damage and affect electrical equipment inside a plane.

Hail, which can grow to the size of softballs, can damage windshields and the exterior of the aircraft. The occurrence of hail indicates sub-freezing temperatures at some height in the cloud.

Even with the warmth of summer, towering thunderstorm clouds easily reach and exceed the freezing level. This also means super-cooled water and the risk of icing is present.

One of the more subtle threats thunderstorms produce is erroneous aneroid altimeter readings due to the rapid pressure changes the storm induces. Readings may be off by 100 feet.

But by far the greatest risk is turbulence. Updrafts and downdrafts within the storm can easily reach 50 mph (73.3 feet per second) and can reach 100 mph (146.6 feet per second). Planes can literally be torn to pieces by the turbulence generated between the up drafts and down drafts.

Even if there is no structural damage to the aircraft, loss of control is a distinct possibility.

And obviously within the cloud, IMC exist and the risk of Controlled Flight into Terrain (CFIT), especially in uneven terrain, is great.

Movement and turbulence of a maturing thunderstorm (FAA graphic).

And keep in mind that convection can develop very quickly. What was VMC everywhere can quickly contain areas of IMC.

TROUBLE ALL AROUND

Dangerous weather conditions are not limited to within the storm cloud itself.

Turbulence above the cloud top can extend upwards for thousands of feet.

Interestingly, the massive core of the storm can actually act as a solid impediment to the prevailing winds, almost like a mountain. Clear Air Turbulence (CAT) can be produced in the air flow downwind of the storm and extend tens of miles.

Beneath the storm cloud base, conditions can also be treacherous. Blinding rain and even hail can extend to the ground. IMC conditions are common.

Extreme downdrafts, called downbursts or microbursts, can occur even without precipitation. Once these downdrafts hit the ground, they can spread out, sometimes for tens of miles, producing strong, shifting winds that can exceed 100 mph, and the dreaded wind shear.

Microbusts can product destructive winds greater than 100 kts. (FAA graphic)

BE PREPARED

Before you start your flight, your preflight weather check, including TAFs and FAs, should highlight any convective problems.

Particularly note any CONVECTIVE SIGMETS, forecasts that warn of dangerous flying conditions due to convection in the next two hours.

But keep in mind, it is impossible to predict exactly when and where thunderstorms will develop in advance. And convection can develop rapidly, sometimes in a matter of minutes.

Closer to takeoff, you can check the latest METARs and PIREPS to see if convection has been reported.

Weather radar is the best tool for locating and tracking thunderstorms. The heavy rainfall rates associated with convection are well depicted as areas of yellow, red, or even purple if hail is present.

Movement and changes in intensity can be determined by tracking storms over time.

Major terminals are well covered by land-based radar. Terminal Doppler Weather Radar can detect thunderstorms and even wind shear near an airport. Larger airports also have specialized wind shear monitoring equipment for the runways. Smaller GA airports are often not as well equipped.

IT’S UP TO YOU

It’s up to the pilot to determine thunderstorm risk. Fortunately with today’s technology, a variety of weather radar products are readily available over the Internet and there are even apps for smartphones.

Always check the time on any radar display you’re checking. Delays due to processing are common. The radar image you’re looking at could be up to 20 minutes old. In fast developing convective situations, that could be crucial.

If your aircraft is equipped with radar, it can be extremely helpful in convective situations. Current radar data is always available, allowing you to detect significant convection 300 nm away.

Source: The Thunderstorm Threat — General Aviation News

AIRBUS Adverse Weather Operations Windshear Awareness

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via AIRBUS Adverse Weather Operations Windshear Awareness — Egyptianaviators

KEY  FACTOR : 

Flight crew awareness and alertness are key factors in the successful application of windshear avoidance and escape / recovery techniques. This Flight Briefing Note provides an overview of operational recommendations and training guidelines for aircraft operation in forecast or suspected windshear or downburst conditions.

REAL DATA : 

Adverse wind conditions (i.e., strong cross winds, tailwind and windshear) are involved in more than 30 percent of approach-and-landing accidents and in 15 percent of events involving CFIT. Windshear is the primary causal factor in 4 percent of approach-and-landing accidents and is the ninth cause of fatalities.

Defining Windshear : 

Windshear is defined as a sudden change of wind velocity and/or direction.
Windshear occurs in all directions, but for convenience, it is measured along vertical and horizontal axis, thus becoming vertical and horizontal windshear:

Vertical windshear: − Variations of the horizontal wind component along the vertical axis, resulting in turbulence that may affect the aircraft airspeed when climbing or descending through the windshear layer − Variations of the wind component of 20 kt per 1000 ft to 30 kt per 1000 ft are typical values, but a vertical windshear may reach up to 10 kt per 100 ft.
 Horizontal windshear: − Variations of the wind component along the horizontal axis (e.g., decreasing headwind or increasing tailwind, or a shift from a headwind to a tailwind) − Variations of wind component may reach up to 100 kt per nautical mile.
Windshear conditions usually are associated with the following weather situations:

• Jet streams • Mountain waves • Frontal surfaces • Thunderstorms and convective clouds • Microbursts.

MICROBURSTS:

 Microbursts combine two distinct threats to aviation safety :cof

• The downburst part, resulting in strong downdrafts (reaching up to 6000 ft/mn of vertical velocity) •

The outburst part, resulting in large horizontal windshear and wind component shift from headwind to tailwind (horizontal winds may reach up to 45 kt).

Windshear and Aircraft Performance :

Headwind gust instantaneously increases the aircraft speed and thus tends to make the aircraft fly above intended path and/or accelerate ( item 1).

. A downdraft affects both the aircraft Angle-Of-Attack (AOA), that increases, and the aircraft path since it makes the aircraft sink ( item 2).

Tailwind gust instantaneously decreases the aircraft speed and thus tends to make the aircraft fly below intended path and/or decelerate ( item 3).

NOTE: 
Windshears associated to jet streams, mountain waves and frontal surfaces usually occur at altitudes that do not present the same risk than microbursts, which occur closer to the ground.

KEY FACTOR : Flight crew awareness and alertness are key factors in the successful application of windshear avoidance and escape / recovery techniques. This Flight Briefing Note provides an overview of operational recommendations and training guidelines for aircraft operation in forecast or suspected windshear or downburst conditions. REAL DATA : Adverse wind conditions (i.e., strong […]

via AIRBUS Adverse Weather Operations Windshear Awareness — Egyptianaviators

The 7 Hardest Parts About Becoming A Private Pilot 

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Everyone knows that crosswind landings are usually challenging for student pilots. But beyond landings (and money!), there’s a lot about learning to fly that can be pretty tough. Here’s what you should be ready for.

The 7 Hardest Parts About Becoming A Private Pilot

By Swayne Martin

Everyone knows that crosswind landings are usually challenging for student pilots. But beyond landings (and money!), there’s a lot about learning to fly that can be pretty tough. Here’s what you should be ready for…

1) Aircraft Systems
One of the toughest topics for private pilot students is aircraft systems. As less and less people grow up working on cars or around machinery, there’s diminishing knowledge behind what makes that engine turn.Want to know more about the systems and equipment in your aircraft? Dig into your POH and read section 7. Better yet, find a local A&P at your airport and have them walk you through a few systems with the cowling off. Getting hands-on with the equipment behind closed panels is a great way to learn how your airplane flies.

2) The National Airspace System
It’s more than identifying lines of airspace on a sectional chart. You’ll need to know what weather minimums exist at different altitudes (day and night), what your equipment requirements are, and what your communication requirements are.
We can help – give our National Airspace System course a try.

3) Learning Regulations
There are hundreds of FAA Regulations that govern how, where, and when you can fly. Some of them can be pretty confusing. As a student pilot, you’re just as responsible for adhering to the FARs as any fully certificated pilot. Keep yourself out of trouble and learn those regs!

4) Aerodynamics
A huge part of learning to fly is understanding the physics behind how it all works. But how can a strong foundation of aerodynamics save your life? One simple example is the lift to drag ratio for your airplane. At L/D max, or the best lift to drag ratio, you’ll find an approximate best glide speed.

5) Decoding Textual Weather
Whether it’s a METAR or PIREP, it’s your responsibility as a pilot to maintain your skills for decoding textual weather.
Need a refresher? Give our Aviation Weather Products course a try.

6) “Radio Talk”
Learning how to actively listen for your callsign in busy airspace with dozens of airplanes on-frequency is tough. Adding that to learning the correct verbiage provides quite the task for brand new student pilots. Here are some things you shouldn’t say over the radio.

7) Getting Into “School Mode”
First and foremost, getting your brain into a “school mode” can be tough, especially if you haven’t sat in a formal classroom setting in years. Learning to fly is undoubtedly fun, but there’s also a lot of work outside the cockpit.

Microlight Trikes Active Recreation by GleBB

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Travel and active recreation. Photo outdoors. Series « Travel, nature and active recreation». Landscape. The natural lighting. via 500px http://ift.tt/2jIMd2B

via Popular on 500px : Microlight trikes _ active recreation by GleBB — Photo Snapping

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