Freezing Rain | SKYbrary Aviation Safety (2024)

FAQs

What should you do if you encounter freezing rain during flight? ›

If you don't have the performance to climb out of the conditions, turning around and flying back to non-icing weather is another option.

Clearly, we cannot operate in those conditions. Traditional deice methods can combat freezing rain, but only in light conditions. Moderate or heavy freezing rain produces conditions that are almost impossible for any airline to operate in.

The METAR code for freezing rain is FZRA. A storm that produces a significant thickness of glaze ice from freezing rain is often referred to as an ice storm.

The answer: Change course and/or altitude; usually, climb to a higher altitude, if possible. Temperature is always wamer than freezing at some higher altitude.

Moreover, de-icing isn't a cure-all. Federal guidelines instruct pilots not to take off in moderate to heavy freezing rain, during heavy snowfall or when ice pellets are falling.

According to the FAA, freezing rain is created when snow falls through a warm layer, then through a sub-zero layer of air - also known as a temperature inversion. These drops fall through the freezing layer so quickly that they don't have time to completely freeze before they get to the ground.

"Only low temperatures will not normally affect flights, planes fly in much colder temperatures at 30-35,000 ft.. Ice and snow are much more likely to cancel flights than just cold temperatures."

Different airplanes have a different maximum operating temperature. Bombardier jets, for example, are designed to operate in temperatures of no more than 118 degrees Fahrenheit, whereas larger Airbus and Boeing jets are able to operate in temperatures of no more than about 126 degrees Fahrenheit.

Bridges, overpasses and elevated roadways are especially suseptible to icing as they are surrounded on all sides by the cold air and freeze more quickly. In addition, ice caused by freezing rain can rapidly add weight to tree branches and power lines, causing them to snap or break.

If the rain falls too heavily, the water washes off and doesn't have time to freeze on contact. It only takes a degree or two to change all of this. We can easily go from 32° to 33° and quickly change from freezing rain to regular rain.

Can rain freeze above 32 degrees? ›

Freezing rain falls when snow encounters a wide warm layer of air, above 32 degrees F, which causes it to melt and re-freeze upon contact with the surface, which is at or below freezing.

If the surface temperature is above 32°F and there is warmer than freezing air above the surface, than you will get just a cold rain. It will not freeze at the ground but will certainly feel cold, especially if temperatures are between 32 and 40 degrees.

Final answer: Flying into rain that freezes on impact can cause aircraft icing, a dangerous scenario where built-up ice alters the aircraft's aerodynamics and interferes with flight sensors or engine intake.

Cold air increases aircraft wing lift and in landing can lead to overshoot or overrun. Inversion can be accompanied with change in wind direction and speed.

Fuel – 100LL or Avgas will freeze at -58°C (-72°F). While the majority of light GA aircraft and pilots will not fly in these conditions, some will fly an aircraft that uses 100LL and has a pressurization system. In this case, you should be aware of this.