One of topics last week for severe weather awareness week was severe thunderstorms. We chose to focus on their impact on aviation through the creation of microbursts.
As we head into this week, the possibility of severe weather looms on the horizon. This could bring the potential of seeing microbursts to our region.
Why Should I Care?
If you have ever traveled somewhere in an airplane, then you may have experienced the following situation.
You are getting ready to land with thunderstorms in the area. All the sudden your aircraft speeds up and you take off back into the sky instead of landing. You might have been annoyed at the fact your flight had to circle back around again before landing.
This would be especially true if you had a short layover, and had to sprint across the airport in order to catch your next flight. You might have thought that your pilot was being inconsiderate, but did you ever stop to think that it might have been a move that potentially saved your life?
Your pilot could have been avoiding a potential run in with a microburst. Aviation and microbursts don’t mix well!
What is a Microburst?
A microburst occurs as a thunderstorm’s updraft collapses and plummets towards the ground. When it hits the ground, it spreads out in all directions. The wind gusts produced by these can reach speeds of over 100 mph! That is the equivalent of an EF-1 tornado. To learn more about these check out our Weather 101 segment on them.
How Do Microbursts Affect Aviation Operations?
In order for an aircraft to land safely, it must decrease its airspeed dramatically. We are talking going from about 500 mph to around 160 mph wheels down.
As an aircraft slows down, the amount of lift decreases as the amount of drag increases. Right before the aircraft lands, it is dangerously close to stalling out. At these slow speeds, an aircraft becomes a target for microbursts.
Upon entering the microburst, the aircraft experiences a sudden increase in airspeed and lift. The strong headwind pitches the nose of the aircraft up. This may cause an inexperienced pilot to pull back on the throttle to bring the nose back towards the ground.
As the aircraft continues through the microburst, it encounters an extremely strong tailwind. This is NOT a good thing, because an aircraft needs to land into the wind in order to maintain lift over the wings. This tailwind takes the lift away from underneath the aircraft’s wings. At such low airspeeds and height the aircraft cannot recover from the loss of lift! It stalls, and crashes into the ground.
Microbursts unfortunately led to an increase in aviation accidents through the 70s.
Aviation and Microbursts Today
Nowadays most major air airports in the United States have installed LLWAS (low level wind shear alert system). These systems are able to warn pilots of a sudden shift in wind speed or direction. Being aware of these changes can allow the aircraft to either avoid or prepare for microbursts.
Certain recovery techniques can also be implemented. As the pilot experiences the strong headwind, they are supposed to increase to full throttle and pitch the nose of the aircraft up until the stall warning sounds. This way when the aircraft hits the strong tailwind they are already at full power, and have the nose of the aircraft pitched up ready to recover from the loss of lift.
Impacts of Microbursts to You
As mentioned earlier, these microbursts can create wind gusts well over 100 mph! These straight-line winds can produce EF-1 tornado damage in some cases. They can tear apart roofs, knock things down, or blow them around. It can be hazardous to be out in these strong winds so make sure to take severe thunderstorm warnings very seriously. If you see a warning issued for your area, make sure to seek the proper shelter immediately.
For other exciting digital weather content, check out other Weather 101, Weather Blog, and Weather Word of the Week pieces.