SIGMETs, AIRMETs, PIREPs - What You Need to Know Before You Go (Credit: Meteorologist Jessica Olsen)5/28/2019  Image Courtesy; NOAA NWS Aviation Weather Center DISCUSSION: Hazardous in-flight weather advisory service (HIWAS) is a program for broadcasting hazardous weather information on a continuous basis over selected VORs (VHF omnidirectional range, it effectively allows the receiver the measure its bearing to or from the beacon, when used in conjunction with a DME (distance measuring equipment) the measurements allow for a position fix, posing a two-fold benefit to using VORs. While HIWAS can be transmitted through the VOR, advisories that are sent to pilots include AIRMETS, SIGMETS, convective SIGMETs, and PIREPs (read below).
According to the Aviation Weather Center, AIRMETs, (AIRman's METeorological Information), "advises of weather that may be hazardous, other than convective activity, to single engine, other light aircraft, and Visual Flight Rule (VFR) pilots." These are often considered widespread, affecting an area of at least 3000 square miles, and are typically issued every 6 hours, which can be amended when needed due to condition/issuance change. While a SIGMET (SIGnificant METeorological Information), according to the Aeronautical Information Manual (FAR AIM) is used to, "advise of non-convective weather that is potentially hazardous to all aircraft." These are often unscheduled but valid for a period of 4 hours, unless associated with a hurricane then valid for 6 hours, similarly to the AIRMET, it can be amended when needed. SIGMETs can be issued for reasons such as volcanic ash, severe icing not associated with thunderstorms, widespread dust storms or sandstorms lowering surface visibilities to below 3 miles, and a variety of other phenomena listed in the FAR AIM. Convective SIGMETs can also be issued and are associated with severe thunderstorms, embedded thunderstorms, squall line thunderstorms, and thunderstorms producing precipitation greater than or equal to heavy precipitation affecting 40 percent or more of an area at least 3000 square miles. Lastly PIREPs (PIlot Weather REPorts), as stated by the Aviation Weather Center, "is reported by a pilot to indicate encounters of hazardous weather such as icing or turbulence." PIREPs are not limited to icing and turbulence but could include reports for ceilings at or below 5000 feet, wind shear, volcanic ash, and several other conditions found in the FAR AIM. Aviators are given a variety of tools to interpret weather, in conjunction with present and future flights. While much of the reporting that pilots use are often available within the ATIS (Automatic Terminal Information Service), a tool that disseminates valuable information regarding current conditions, approach/departure, instructions and more, it is all being verified after the pilot reports the ICAO letter associated with the ATIS report indicating the pilot has reviewed current ATIS information to the controller (tower, ground, approach/departure, center), some ATIS reports will communicate SIGMETs/AIRMETs/PIREPs in addition to the standard, abbreviates or outlook brief that a pilot could obtain from 1800WXBrief. For more information on aviation meteorology visit the Global Weather and Climate Center! © Meteorologist Jessica Olsen Referenced: F. (2014, April 3). Retrieved May 27, 2019, from http://www.faraim.org/aim/aim-4-03-14-437.html N. (n.d.). What is an AIRMET? Retrieved from https://www.weather.gov/source/zhu/ZHU_Training_Page/Weather_Keys/AIRMETs/AIRMET.htm
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 DISCUSSION: According to Aircraft Owners and Pilots Associations (AOPA), density altitude is pressure altitude corrected for nonstandard temperature. It has been referred to as the actual altitude at which the plane “feels” it is flying. Whereas pressure altitude is the indicated altitude when an altimeter is set to 29.92 Hg. This density altitude has a direct correlation to aircraft performance. Typical performance is based on 15°C and 29.92 Hg, often found in the Pilots Operating Handbook (POH). However often when flying, conditions are rarely as the published conditions are a brief reference for performance. The Federal Aviation Administration has put out a publication on Density Altitude, in an effort to increase pilot awareness of the subject when flying in other than standard conditions. High density altitude corresponds to reduces air density and thus a reduced aircraft performance. Keeping density altitude in mind, there are 3 factors that contribute to increased density altitude:
Effects on the aircraft are decreased aerodynamic performances, and diminished engine horsepower output. This in turn will influence takeoff distance, power available, climb rate and landing distance. Density altitude is said to increase takeoff distance, decrease rate of climb, increase true airspeed on approach and landing and increased landing roll, all critical elements in a pilot’s operation of the aircraft. The FAA recommend that if the Airplane Flight Manual (AFM)/Pilots Operating Handbook (POH) are unavailable use the Koch Chart to calculate adjustments. In addition to this, this does not account for leaning the mixture may be necessary for maximum power on takeoff, otherwise adding to the decreased performance if mixture is not leaned. © 2019 Meteorologist Jessica Olsen Referenced: Federal Aviation Administration. (2008). Density Altitude. Retrieved April 15, 2019, from https://www.faasafety.gov/files/gslac/library/documents/2011/Aug/56396/FAA P-8740-02 DensityAltitude[hi-res] branded.pdf  DISCUSSION: Since the onset of the global aviation industry, there is no question that winter weather issues are consistently a major concern for the timeliness, the safety, and the overall reputation of given global aviation networks. Across the north-central U.S. and even more so across the northeastern U.S. states, it is not uncommon to find a Winter-time scenario where you find a relatively minor winter weather event or even an all-out blizzard slowing ground and air travel to a slow crawl (or even halt). The obvious impacts which most people think of is how a given winter storm will affect their specific travel plans and what that could mean for their upcoming schedule in terms of arrival times and other corresponding accommodations at their destination.
However, there is substantially more than just that which goes into figuring out how and to what extent winter weather can affect both national and international aviation networks and interconnected aviation networks therein. For starters, one of the major issues is that when a major snowstorm impacts (for example) the Interstate-95 (I-95) corridor from roughly Washington D.C. to Bangor, Maine, such a storm can impact major airports including (but certainly not limited to) Washington Dulles International Airport, Philadelphia International Airport, Newark Liberty International Airport, John F. Kennedy International Airport, LaGuardia Airport, and Boston Logan International Airport in a dramatic fashion. Now, as much as such flight delays and/or cancellations can be a major inconvenience for impacted travelers trying to fly out of those cities, there are other “pieces to this puzzle” which are not always quite as obvious to the average traveler. More specifically, whenever a given flight is delayed and/or cancelled out of a given airport, all the passengers who are ticketed for a delayed and/or cancelled flight are consequently not able to make connecting flights at other airports which leads to increased airport and travel congestion in each impacted region due to a winter storm. Thus, this acts to prevent passengers from leaving and thus leads to a surplus of people awaiting flight arrangements for the following day with a finite number of flights scheduled to leave the airport on a given day. Thus, making the travel headaches in an impacted city that much more complicated. Moreover, not only do major winter storms have the potential to impact regional and national travel, but they can often impact global aviation networks via a given winter storm preventing other flights from around the world to depart for any of the above impacted cities along the I-95 corridor. Therefore, many larger aircraft which are responsible for most of the service for longer international flights are consequently grounded which can potentially leave hundreds of thousands of passengers stranded and waiting for alternate connecting flights to get around the worst of a given snowstorm from cities spread around the world. Furthermore, there are only so many aircraft in a given commercial airline company which can sustain the mileage needed to get across large oceanic basin such as the Atlantic and/or the Pacific Oceans. This reality will place further limits on how long it will take a given airline to restore a sense of balance in their global aviation flight plan for the days and even to up a week after a given snowstorm comes to an end. Thus, this goes to show that the national and international impacts from a blockbuster winter storm are not even close to as simple as one may think. To learn more about other interesting global aviation topics, be sure to click here! © 2019 Meteorologist Jordan Rabinowitz  Image Courtesy: Airbus DISCUSSION: Often many do not see the connection between aviation and meteorology, there can be a basic assumption that aircraft can withstand a wide variety of weather phenomena, which is often true but some are lacking in overall capability. In addition to specialized instruments needed for aircraft, basic meteorology is on the forefront of a major phenomena that most airline passengers typically ask meteorologists about, turbulence.
According to the American Meteorological Society, aircraft turbulence is, “ irregular motion of an aircraft in flight, especially when characterized by rapid up-and-down motion, caused by a rapid variation of atmospheric wind velocities.” Which, “this can occur in cloudy areas (particularly towering cumulus and lenticular clouds) and in clear air. Turbulence is the leading cause of nonfatal passenger and flight attendant injuries. The U.S. Federal Aviation Administration (FAA) classifies aircraft turbulence as follows:
While there are a variety of aircraft that do not have operational limitations, some aircraft such as the Canadair (CRJ) 200 or Embraer (ERJ) 140/45, often must remain grounded (until weather should pass) due to lack of ACARS (Aircraft Communications Addressing and Reporting System) (CRJ 200), and weight and balance issues. Aircraft and its flight are also limited to the use of visual flight rules (VFR) or instrument flight rules (IFR) based on aircraft and pilot ratings. Turbulence is by far one of the most noticeable connections between aviation and meteorology, of course behind the use of air as a fluid, the forces of flight and Bernoulli’s Principle. As we investigate turbulence, we can often just deduce that turbulence is the flow of atmospheric winds due to the rising and sinking of air in the atmosphere. Should we further explore wind in turbulent flow we can consider that all turbulence is, is atmospheric motion, and as height increased, pressure typically decreases, with wind increasing, creating various components of vertical motion going on while moving horizontally in the atmosphere within an aircraft. Airbus has created the A220-100, built as the smallest jetliner in the Airbus family, designed to serve the 100-135 seat market, in addition to the A220-300 to serve the 130-160 market. These new aircraft are attempting to put down the days of the MD-80, and B717 while providing an economical and efficient aircraft, compared to previous iterations. What is of note is its turbulence avoidance technology which according to CBS News, “shows pilots where the smooth air is by crowdsourcing data from all of Delta's aircraft.” Pilots are hailing this new technology, rather than attempting to maneuver the aircraft to find it, it can be found on the instrument panel. In addition to this valuable technology the aircraft was designed for hot, and high, city-like environments, an ideal aircraft for places like Phoenix’s Sky Harbor International Airport where extreme temperatures often limit aircraft arrivals and departures in the summer months. For further information on aviation and weather visit the Global Weather and Climate Center! © 2019 Meteorologist Jessica Olsen Resources: “A220-100.” Airbus, Airbus, www.airbus.com/aircraft/passenger-aircraft/a220-family/a220-100.html. Van Cleave, Kris. “Delta's New Airbus A220 Features Wider Coach Seats and Turbulence Avoidance Technology.” CBS News, CBS News, 28 Dec. 2018, www.cbsnews.com/news/new-delta-airbus-a220-features-wider-coach-seats-turbulence-avoidance-tech/.  DISCUSSION: As more and more people find various needs to travel via commercial aviation from around the globe, there is an increased demand for there to be more and more flights offered to various destinations around the world. There is no question that this increased flight demand puts substantial strain on Earth-bound fossil fuel resources which are continuing to be depleted at a greater and greater rate with every passing day, month, and year. Having said that, in a modern era which we are living in where we have direct access to cutting-edge fuel-based technologies, there is much more that mankind can still do to offset the tremendous environmental impacts which are imposed by global commercial and private aviation. For starters, several airplane manufacturing companies have already begun in earnest with the development of new and innovative aircraft and aircraft engine designs to greatly improve the overall fuel efficiency of various aircraft types.
However, even with the reduction of the impact of commercial and private global aviation flight demands in terms of the net fuel consumption issues, there is still more which can and is starting to be done behind the scenes. For example, as the story attached in the link below reflects, there are several different ways in which global aviation companies and component developers thereof can make further progress in how aviation can evolve as we continue moving further into the 21st century. In light of large amounts of scientists also traveling to global science research conferences around the world on a yearly basis such as the American Meteorological Society's 99th Annual Meeting being held in Phoenix, Arizona here in the 1st to 2nd week of January here in 2019, this is most certainly a relevant and a hot-button topic without question. Whether it is developing solar cell-based technologies or water and hydrogen-based fuel technologies, there is a tremendous amount of current and future versatility which will be possible for the continued improvement of mitigating environmental impacts of air travel. Having said that, it is still important to point out the fact that the best way to limit any individual impact to Earth’s global carbon footprint is to limit the amount of flying which is done. When you can, try to utilize other means of travel which have somewhat less of a net carbon impact on planet Earth which is also referenced in a bit greater detail in the article attached below. Having said that, the development of more modern aircraft such as the Airbus A350-900 and newer versions of the Airbus A-330 are most certainly a step in the right direction. To learn more about this particular article which was courtesy of dw.com, click here! To learn more about other neat aviation topics from around the world, click here! © 2019 Meteorologist Jordan Rabinowitz  DISCUSSION: Around the world every day, there are major issues when it comes to airports and private and/or commercial aircraft dealing with various types of fog. First and foremost, the more common types of fog which include ground fog and advection fog, will often create substantially reduced visibilities in and around area airports during such circumstances. Reduced visibilities are a major hazard to approaching and departing aircraft since such conditions can make simple aircraft functionality a very dangerous precedent. More specifically, when it comes to flying through or around fog banks early in the morning or at night, there can often be points at which the fog is present at variable concentrations from top to bottom. For that reason, the idea of flying through a fog bank can be even more concerning since the unpredictable variability of a fog bank’s thickness can lead to a pilot or set of pilots being unable to see the runway.
Even with state-of-the-art technologies built into modern aircraft and various tools which allow pilots to more easily handle flying through various types of inclement weather, deep fog can still be especially dangerous to any type of private or commercial aircraft. Therefore, any time that pilots are confronted with situations which involve deep fog banks and must abort an approach and landing at a given airport, do not get frustrated with your pilots since there is a good chance that they had a very legitimate reason for aborting the landing and making another approach from a different direction. Another issue tied to the presence of fog and corresponding flight delays is very much like the issues faced by airports with any other type of inclement weather situation. That is, the reality that any situations involving persistent fog will often lead to scenarios where there are corresponding flight delays. Thus, a deep, persistent fog bank can create substantial regional, national, or possibly even global flight delay issues for some period as a result of passengers not being able to make subsequent flights and planes being forced to wait for the arrival of large numbers of passengers from delayed flights. Thus, this just goes to show that there is always a corresponding impact which can be observed in a statistical manner with respect to flight delays from regional fog events. To learn more about other global aviation topics, be sure to click here! © 2019 Meteorologist Jordan Rabinowitz  DISCUSSION: Every day around the world, millions and millions of people travel via private and/or commercial aircraft to get to various places they need to travel to for business or leisure. Thus, it goes without saying that the international aviation network is a complex organism which needs near-constant attention from global air traffic control networks. Whenever there are “disturbances” which impact any part of the global aviation network, there are always consequential “ripples” in the timing of departing and arriving aircraft and corresponding connecting flights. One such example of this issue has to do with the impact that sandstorms have on private and commercial aviation.
To elaborate on this issue, whenever airports across the Southwest United States, the Middle East, and other places around the world are impacted by sandstorms which are induced by stronger winds which push across desert or desert-like regions, there are some major issues which arise. First off, whenever sandstorms impact airports, there is a substantial impact on local and potentially regional visibility extent. For this reason, this makes the paths for departing and arriving aircraft much more dangerous since pilots of any aircraft will not be able to see critical airports markers and lights as they attempt to taxi to the runway or approaching the start of the runway. Another issue when it comes to taking off or landing on a given runway within a progressing sandstorm is the fact that sandstorm will often bring with them very unpredictable wind flow patterns. Thus, the corresponding erratic wind speeds and directions within a given sandstorm has the potential to create incredibly hazardous cross-winds which can make the dangerous unpredictable wind flow regimes as well as the greatly reduced visibilities a seriously life-threatening situation when it comes to general aviation interests. One of the other primary issues which can sometimes arise when it comes to sandstorm impacts on aviation is the inherent associated with damage to aircraft and aircraft engines. When sandstorms impact various sized aircraft either on the ground or even more so in the air, the high speed of the aircraft combined with the effective “pelting” of the sand particles on the fuselage, the wings, or even the engines of the aircraft can have a substantial impact on the physical integrity of the engine components which help to power major parts and functions of any aircraft. Depending on how the size of the sand particles are distributed within a given sandstorm, the fan blades of many turbofan engines can often be damaged by ingesting too much sand within a given sandstorm event. Thus, it goes without saying that sandstorms can have profound impacts on general aviation safety. To learn more about other global aviation topics, be sure to click here! © 2019 Meteorologist Jordan Rabinowitz  DISCUSSION: During a typical Winter Storm, there is no question that one of the biggest stresses for world travelers are the impacts delivered to the global aviation network. First and foremost, one of the biggest threats to both private and commercial aviation threats is the inherent threat tied to both ground and in-flight icing which can unfold do to snow and ice accumulating on aircraft bodies and wings as well. The reason for why this is so hazardous to aircraft of any kind is because any accumulation of snow and/or ice can often lead to a loss of stable flight via a disruption of even, balanced airflow over the length of the wings as well as a common imbalance in the distribution of weight via ice accumulation during a given flight.
To dive deeper into this process courtesy of the How Stuff Works website, “Deicing agents are compounds made up of the chemical glycol and water. Glycol lowers the freezing point of the solvent, water. The agents are used in different formulations for different weather conditions, but whatever the formulation, the compound is applied in the same way. It is heated and sprayed through a hose over an airplane to remove snow, ice or frost. Pilots make the call for deicing when necessary and oversee the process, which must be done in accordance with detailed Federal Aviation Administration (FAA) rules. In fact, the FAA rules chapter on deicing runs more than 30 pages and covers everything from makeup and handling of the deicing compound to its application, how quickly it must be applied and the documentation required following each deicing occurrence. Speed and thoroughness are essential in applying deicer. As such, applications must be performed in a timely and well-ordered fashion, with an eye on what's called holdover time, the amount of time following deicing before the plane has iced-over again and must be re-treated. Holdover time varies based on the makeup of the compound and is set by the fluid manufacturer. With deicing compounds costing upwards of $5 per gallon, the procedure can cost thousands of dollars (factoring in handling and storage costs), so it's essential that holdover times not be exceeded. Holdover time also explains why deicing is performed after everyone is on board and the plane is otherwise ready to take off. Holdover time may only be a few minutes, so the plane must be ready to taxi onto the runway and get into the air soon after deicers are applied. Deicing agents are generally not designed to keep ice or frost from re-forming on the plane. So, if snow, sleet or freezing rain is actively falling as an airplane is being deiced, the plane may also need an anti-icing application to keep ice from re-forming before the plane takes off. Anti-icing fluids are also made up of glycol and water, but with a higher concentration of glycol than deicing fluids. A thickening agent is added to help the compound adhere to the plane as it takes off.” Thus, this explanation just goes to show that even during the heart of the worst Winter storms which you may face in life, it is imperative to always be understanding when it comes to ground-stops which may come to reality at a given airport. Namely, since many larger airports cannot always keep up with icing both on the aircraft and the wings of aircraft both on the ground and in the air. Hence, the phrase “patience is a virtue” will often come into play during the cold days of Winter. To learn more about other interesting aviation topics, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  DISCUSSION: There is no question whatsoever that there is a lot of mystery when it comes to understanding various things about the aviation industry. One such mystery is all about what it takes to fly a plane under different types of low and/or mid-level environmental conditions. This difference primarily has to do with whether a pilot or co-pilot of a given aircraft is flying under IFR or VFR flight rules. That is whether a situation has sufficiently clear and calm conditions for a given pilot to steer a plane via natural eye-sight abilities or if a pilot needs to rely on aircraft-based instrumentation as well as regional air-traffic controller (ATC) staff members at a given airport.
Attached above is a short video briefing detailing the most important differences between IFR and VFR flight rules to learn more about these unique differences. To learn more about this topic via the original article, feel free to click here! To learn more about other interesting aviation-based topics/issues from around the world, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  DISCUSSION: During a given Winter season, there is no question that various types of wintry weather can have a profound impact on aviation. For example, during icing events, there are often major delays which are created across the aviation industry. The reason for this is a result of the fact that as ice accumulates on both airport runways and aircraft of all sizes, this makes for an increasingly more hazardous situation for both crew and passengers alike. One of the key factors involved in creating a safe environment for both takeoffs and landings is the presence of enough friction between aircraft tires and tarmac as well as the corresponding runways which given aircraft will taking off from and landing on.
Hence, during an ice storm, this reality is often not met and thus, will quite often lead to massive flight delays and/or cancellations across the industry as a result of global aircraft route “ripple effect” which occurs. This a big part of the reason for why even though a snowstorm may impact only region of the United States or a specific section of Europe, the regional delays and/or cancellations create a chain reaction on a global scale which ultimately acts to “ground” other people both around the country and around the world. In addition, during more intense parts of snowstorms, icy runways are not the only aviation concern. From an even simpler perspective, intense parts of given snowstorms inherently have heavier falling and/or blowing snowfall which will often lead to reduced visibilities. Hence, the reduced visibilities associated with more intense snowstorms can create insufficient aviation-based conditions for takeoffs and/or landings which makes for very hazardous scenarios for any aircraft which attempt to land during snowstorms. Therefore, if you make plans to travel via commercial and/or private aircraft near the time of or during a given winter storm, this can lead to tremendous travel hazards for you and your family. To learn more about other interesting aviation-based weather topics from around the world, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz |
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