Flight Dispatchers & Thunderstorms
As summer kicks off so do the thunderstorms and this means a busy time for the dispatch world. Despite advances in technology, these summer storms still pose a threat to aircraft and it's vital for an aircraft dispatcher to properly plan and monitor flights while operating in such an adverse environment. Constructing tailored routes specific to each thunderstorm’s movement and velocity demands a high level of focus and understanding of the life of a thunderstorm.
What exactly is a thunderstorm and what causes one?
Well, plain and simple, a thunderstorm is a storm that contains lighting and thunder, usually producing gusty strong winds, heavy amounts of precipitation and occasional hail. For a thunderstorm to develop into a full blown storm you need three main ingredients: moisture, unstable air, and some sort of lifting action. Moist air will cause clouds to develop in the atmosphere. The unstable air is relatively warm and can cause the air to rise rapidly. Finally lift can be produced from fronts, sea breezes or even with the help of mountains.
Life of a Thunderstorm
There are three stages of a thunderstorm: the cumulus, mature, and dissipating stages. The cumulus stage is the beginning stage of the storm, where you’ll see rapid updrafts and towering cumulonimbus clouds. The mature stage is the point where the thunderstorm is fully developed and the heaviest rain occurs. This is also when downdrafts begin within the system and the associated clouds approach their peak altitude, the tropopause, where the troposphere meets the stratosphere. The dissipating stage is the thunderstorms last ditch effort in its “fight,” where downdrafts take over the entire storm and with that, the storm deprives itself of supersaturated air (taking itself out). Precipitation decreases and the clouds taper off.
Dispatchers work really hard to construct and produce a route that complies with air traffic constraints and safely allows complete thunderstorm avoidance. However, weather can be very dynamic, altering flight plans while in-flight. This is where a dispatcher's multitasking skills must be utilized. Not only does the dispatcher need to produce a tailored route to the flights on the ground, they must also keep track of developments and provide safe weather deviations to airborne flights.
Clear air turbulence is another threat that needs to be considered, especially when flying over storms, which is why if it's permitted, the flight will go around the weather and not over.
Clear air turbulence is the turbulent movement of air masses in the absence of any visual cues like clouds. It's caused when bodies of air that are traveling at different speeds meet, something that cannot detected by radar.
Information relayed to the flight crew is not only the obvious location of the moving thunderstorm cells but also the intensity/echo tops. The dispatcher has the ability to look at other traffic in the vicinity (company and other airlines) and see how they’re being routed around the significant weather. Comparing the different types of planes that are going through weather is also a great way to interpret ride reports coming from those flights and the intensity of the weather. For example, a report of severe turbulence for a CRJ might be considered light/moderate to an Airbus A380. Bottom line, avoiding these nasty storms generally means flying around them because they can reach as high as 60,000 feet, well above the service ceiling of any commercial jetliner.