Safety Article

Maintaining safety of flight with seasonal changes


While every season produces unique obstacles to maintaining safety of flight, the summer months bring with them a consortium of environmental, airspace, and physiological challenges that can easily catch pilots by surprise. Even on perfectly clear days, high density altitudes can compromise aircraft performance capabilities, a dilemma shared in both general aviation and commercial flying. Additionally, thermal turbulence caused by rapidly increasing surface temperatures during the day can rapidly go from being a nuisance to compromising the safety of flight, often fostering the development of afternoon thunderstorms. With the beginning of the fire season, as well, pilots must familiarize themselves with current TFRs (temporary flight restrictions), commonly issued to provide airspace separation for aerial firefighting activities.  Pilots must approach all of these external challenges while combating a number of physiological concerns associated with high cockpit temperatures. While summer flying poses many additional challenges to all pilots, a comprehensive understanding of the factors affecting flight safety inspires confidence in the decisions made both during pre-flight and while in the air.

Higher density altitudes, precipitated by warmer atmospheric temperatures, mean that aircraft will be flying closer to their performance limitations. While weight and balance, and aircraft performance calculations are a pertinent aspect of every pre-flight procedure, these become all more critical when aircraft climb rates are inhibited by reduced air density. Aircraft performance is negatively impacted by decreases in atmospheric pressure, increases in air temperature, and increases in relative humidity. All of these factors act to energize air particles and cause greater separation between individual atmospheric molecules. This energized state affects aircraft operation in a number of ways: a normally aspirated engine will have a reduced capacity to produce horsepower and all aerodynamic surfaces, including a propeller or turbine system, will have a reduced capacity to produce lift. These concerns are not the  sole challenge of low altitude, general aviation pilots; even pilots of higher performance aircraft cruising in the flight levels must consider the effects that higher than standard temperatures at altitude have on aircraft
climb performance and absolute ceiling. Although jet-powered aircraft generate a great deal more thrust than their general aviation counterparts, they tend to be operated much closer to the edges of their performance envelopes. Exceeding specified performance limitations has led to numerous high-altitude upsets, including the loss of Air France Flight 447 (accident report can be found here:  https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf). All pilots must understand and comply with the performance limitations of their aircraft, a consideration that becomes exceptionally pertinent on hot, summer days.

In the Northern Hemisphere, thunderstorms occur most frequently between the months of May and August. The surprisingly fast development and movement of convective areas demands thorough pre-flight weather consideration. Although there are many publicly-available resources from which pilots may become aware of local atmospheric conditions, a weather briefer should be contacted (at 1-800-WX-BRIEF) prior to departing on every flight. A standard weather briefing not only informs pilots of potential adverse conditions along their intended route, but also includes a review of the applicable NOTAMs (Notices to Airmen) along the planned route
and at each airport of intended landing. Although pilots often have multiple routing options to reach their destination, careful flight planning can be life-saving by providing adequate alternatives when an unanticipated weather system moves in. While it can be a challenging decision to cancel a flight for any reason, use of a personal minimums worksheet (available here to fill out: https://www.faa.gov/news/safety_briefing/2015/media/Personal-Minimums.pdf) can remove much of the subjectivity in these determinations regarding current and forecast weather conditions. Although it is always better to make weather decisions prior to departing on a flight,
pilots must continuously use their judgment and learned aeronautical decision-making skills while in-flight. Weather information is available to pilots in most areas from the air by contacting a Flight Service Station. Additionally, in tower controlled airspace, ATC (air traffic control) can provide a great deal of assistance to pilots experiencing challenges. Pilots must learn about, and utilize, the extensive resources at their disposal in order to ensure safety in all flight operations.

In addition to an increase in convective activity, there is an additional increase in special flight operations conducted during the summer months. Especially in the hot, dry climate of Utah, forest fires often complicate civilian airspace through the emergence of TFRs (Temporary Flight Restrictions), issued for the purpose of maintaining separation between aerial firefighting operations and civilian aircraft. To get the most up-to-date information on the activity of Special Use Airspace, including TFRs, it is important to check all NOTAMs (notices to airmen) before every flight; a reliable source for checking current NOTAMs (and weather along your route) is to
call a weather briefer. AOPA released an article providing additional suggestions to ensure avoidance of any and all temporary flight restrictions as they appear: https://www.aopa.org/news-and-media/all-news/2004/march/flight-training-magazine/keepingtrack-of-tfrs. Pilots are responsible for ensuring that their operations are conducted in accordance with all applicable airspace regulations, and invading an active TFR could additionally compromise both pilot safety and the ability for certain special flight operations to be conducted.

Certain physiological conditions often become neglected as pilots gain experience and flying becomes more routine. The IMSAFE (illness, medication, stress, alcohol, fatigue, and eating/emotion) self-assessment can help to effectively assess many physiological conditions that could impair a pilot’s fitness for flight. However, with summer weather upon us, additional precautions are necessary. Even at the low altitudes flown by most general aviation aircraft, dehydration can act to impair pilot judgment, possibly without immediate recognition. In the dry heat of the Salt Lake valley during summer, it can be surprisingly easy to become dehydrated.  The FAA has written an article specifically dedicated to the dangers of pilot dehydration, advising various protocol to avoid falling susceptible to a state of dehydration, including a recommended daily consumption of two to four quarts of water. Additional suggestions given by the FAA to combat dehydration can be found here: https://www.faa.gov/pilots/training/airman_education/topics_of_interest/dehydration/. Summer weather is not only responsible for increased pilot dehydration; the high heat and extended length of summer days can also be surprisingly fatiguing. In addition to numerous environmental factors, summer flying requires the constant analysis of a pilot’s physical condition.


Garret Wilcox

Westminster College CFI