Mountain Flying with a Trike, Weather Considerations
Mountain flying is stunningly beautiful while also risky. According to the AOPA site on
average 17 people die annually just in the Colorado mountains in general aviation
(GE) airplane accidents.
Trikes are probably the smallest of aircrafts that can do long cross country flights in the
mountains with careful weather planning.
Here is why I think flying a trike is an incredible experience compared to flying larger
airplanes:
Flying in the mountains with a trike is an incredible experience. While not being busy
navigating, wrestling the turbulence or being cold I spent my time looking at the scenery with
complete astonishment.
These are some of the risks of flying trikes in mountainous areas and strategies to
mitigate them:
First of all I have read and watched everything I could about mountain flying - books, online
articles and youtube videos. I also talked to more experienced pilots. Sparky Imeson's
Mountain Flying Bible is a good book to start with.
I religiously watched the winds aloft forecasts and set my personal limit at 25kts. at mountain
peak level. A great way to watch winds aloft is using an internet phone with applications like
ForeFlight or AirWX. Similarly I watched sealing levels and tried to get it at least 2000ft above
my flight level. These programs also provide TFRs, NOTAMs, asos, awos, radar images,
pireps, sigmets and prognostic charts.
Trikes are limited by FAA to fly up to 10.000ft ASL, This is a serious limitation and many
mountain passes are not flyable at this elevation. The recommended clearance over ridges is
2000' which I have always kept. This prevented me from flying over many routes and required
very careful flight planning and finding alternate passes. This also means that one has to get
used to flying below the level of peaks and ridges.
My trike climbs at over 1000ft/min at sea level, but at 10.000ft loaded with gear and fuel the
maximum sustained climb rate is only 150ft/min. This is way below the rate of sinks I have
encountered (1000+ft/min). The right strategy is scary but works - dive through the sinks
instead of trying to out-climb them.
Flying in the middle of the valleys - not always the right strategy. In cross winds it is better to
stick to the windward side of the valley and use the lifts along the ridges. During the day when
the sun warms up the hills the middle of the valley can present down drafts. I felt comfortable
staying close to the mountains since I did a bunch of ridge soaring as a glider pilot. Ridge lifts
seem to neutralize the rotors coming from the leeward side of the valley. One has to be aware
of the dangers of ridge soaring too. You have to be pretty close to the mountain to stay in the
lifting zone - at this elevation and wind speed an engine out with a trike means landing in the
forest within 20 seconds. I did land in the forest with a glider plane - it is a very unpleasant
experience... Cracks and crevices are also dangerous, the wind funnels through them and it
can speed up to 2-3 times of it's normal speed. In this situation the trike can be blown back
behind the mountain and may get into severe turbulence. The third danger of ridge soaring is
wind shear over the trees which tries to turn the trike into the forest. As Sparky recommends in
his book - I tried to visualize wind as water flowing across the mountains and it helped to see
the turbulent zones.
I always tried to be aware of the wind direction and often did 360 degree turns to map it out.
What the book writes is true - wind speed may be multiplied by the mountains. I was flying in
20kt winds aloft and clocked over 110+mph ground speed - while my trim speed is only 60mph.
Not considering the effect of density altitude it means 50+mph wind speed.
Other problem - there are no alternate routes. If the mountain pass is barely VFR or raining
along the route - there is no way to fly around it. This was the reason I spent a whole day on
the ground close to Yellowstone waiting for the rain to clear the pass.
Weather changes extremely fast in the mountains. I was sitting on the ground contemplating on
flying. Between two waves of the cold front a nice blue hole was moving along. I stayed on the
ground and in 5 minutes there were a few innocent looking cumulus clouds in the blue hole. In
30 minutes they merged and grew to a major cumulonimbus. I was so glad to be on the ground.
Sometimes the air is very smooth under the morning inversion as it blocks the rotors coming
from the mountains and it is worth flying low. But most of the time the saying is true - elevation
is your friend.
Quickly changing weather also means that it is best to fly short hops and have designated
emergency airports to land at. I had to use one of my emergency landing spots as the clouds
formed a solid wall in front of me with rain all the way to the ground. Flying in rain is not fun, it
reduces the plane's performance and comes with strong turbulent down-drafts that can go all
the way to the ground just like microbursts.
When flying through long mountain valleys I watch the weather behind me to make sure I do
not loose VFR and have the option to turn back. When you enter the mountains you can
never be sure what the weather will look like in two hours and 120miles down the valley.
In mountain flying the rule is to approach the ridges at a 45 degree angle. This enables the
pilot to turn back to lower ground. For trikes which can turn on a dime compared to GA I just
changed this rule to always have an escape route. I also considered the wind direction,
speed and possible turbulence when selecting escape routes and landing spots.
Forget the traffic pattern when landing on small mountain airfields. They are very rarely used
and the best pattern is that puts you down safely. Often they are tucked between mountains
with areas of rotors. The best is to drop through those rotors or keep the distance from the
hills and other rotor inducing objects.
Many mountain fields have a significant down-slope that is invisible from the air. Soft field and
cross wind landings and take-offs are also normal, often the direction of the landing strip is
dictated by the terrain and not by the usual wind direction. Check the density altitude on asos,
even trikes can feel sluggish at take off at 8500' DA.
On high plateaus the ground elevation is 3-4000ft, the cloud base is at 8000 and the top of the
clouds reach way over 10000ft. This means that a light sport plane can not climb over the
weather and has to fly in convective air. I found the best elevation to fly is where the thermals
kicking off the ground are already wider and smoother but the influence of the clouds are not
too strong yet. Flying along rivers may help, I found that the Snake River had a strong cooling
effect blocking the thermals.
The great thing about trikes - being exposed to the elements is also a disadvantage. One can
get very cold and exhausted after a few hours of wrestling with the turbulence. Paying attention
to your own well being is very important. Like on sailboats - one hand for yourself, one hand
for your boat (plane). I used up to 5 layers of polartech on top and three on bottom under the
pilot suite. I also made sure never get sweaty when on the ground so I spent a significant
amount of time adding and removing layers. A polartech sweater is about $80 at REI. I did not
want to spend that much so I got them from local thrift stores for less then $10 each... Since I
commute on a motorcycle I am used to cold, rain and wind and built up some tolerance to the
elements. Still at times I felt hypothermic when flying and was glad to land. Hypothermia
reduces the ability to think and stay focused.
My trike's endurance is not great when flying at high altitudes. The fuel consumption goes from
2.4Gal/hour to over 4Gal/hour as the rpm goes from 4000 to 5200 at level flight. The next
instrument I will install will be a fuel flow gauge which can give me a good endurance estimate.
One of my biggest weakness is my spotty weather knowledge. I will learn to read the clouds
better and understand the local and regional weather more. The available weather tools
provide an incredible array of information.
Convective air movement is multiplied by the mountains. I had 900ft/min lifts and similar sinks
along the way. Generally the plane can easily take these air movements and the pilot gets
tired first. For this reason I flew from the early morning and into the early afternoon until I got
too tired and had enough wrestling with the thermals. For my next trip I will install wingtip
position lights so I can fly in civil twilight.
If you were able to take this much "wisdom" in one reading - you must be a very dedicated trike
pilot. Please let me know if you have other or different experiences when flying in mountains.
These are a few photos of pretty clouds and other weather events I have
encountered along the way:
Cumulus congestus:
average 17 people die annually just in the Colorado mountains in general aviation
(GE) airplane accidents.
Trikes are probably the smallest of aircrafts that can do long cross country flights in the
mountains with careful weather planning.
Here is why I think flying a trike is an incredible experience compared to flying larger
airplanes:
- You hold on to the control bar that is directly attached to the wing, you feel every small
(and large) air movement. You control your flight directly, not through a complex set of
wires and push rods. Your body is a significant part of the fuselage and by moving, it
changes the geometry of the flexible wing and steers the trike.
- You sit outside - with no cabin, no isolation, no barrier. Nothing blocks the view between
you and what is around you. You feel the differences of temperatures, the wind blowing,
feel the smell of the forests and rivers you are flying by.
Flying in the mountains with a trike is an incredible experience. While not being busy
navigating, wrestling the turbulence or being cold I spent my time looking at the scenery with
complete astonishment.
These are some of the risks of flying trikes in mountainous areas and strategies to
mitigate them:
First of all I have read and watched everything I could about mountain flying - books, online
articles and youtube videos. I also talked to more experienced pilots. Sparky Imeson's
Mountain Flying Bible is a good book to start with.
I religiously watched the winds aloft forecasts and set my personal limit at 25kts. at mountain
peak level. A great way to watch winds aloft is using an internet phone with applications like
ForeFlight or AirWX. Similarly I watched sealing levels and tried to get it at least 2000ft above
my flight level. These programs also provide TFRs, NOTAMs, asos, awos, radar images,
pireps, sigmets and prognostic charts.
Trikes are limited by FAA to fly up to 10.000ft ASL, This is a serious limitation and many
mountain passes are not flyable at this elevation. The recommended clearance over ridges is
2000' which I have always kept. This prevented me from flying over many routes and required
very careful flight planning and finding alternate passes. This also means that one has to get
used to flying below the level of peaks and ridges.
My trike climbs at over 1000ft/min at sea level, but at 10.000ft loaded with gear and fuel the
maximum sustained climb rate is only 150ft/min. This is way below the rate of sinks I have
encountered (1000+ft/min). The right strategy is scary but works - dive through the sinks
instead of trying to out-climb them.
Flying in the middle of the valleys - not always the right strategy. In cross winds it is better to
stick to the windward side of the valley and use the lifts along the ridges. During the day when
the sun warms up the hills the middle of the valley can present down drafts. I felt comfortable
staying close to the mountains since I did a bunch of ridge soaring as a glider pilot. Ridge lifts
seem to neutralize the rotors coming from the leeward side of the valley. One has to be aware
of the dangers of ridge soaring too. You have to be pretty close to the mountain to stay in the
lifting zone - at this elevation and wind speed an engine out with a trike means landing in the
forest within 20 seconds. I did land in the forest with a glider plane - it is a very unpleasant
experience... Cracks and crevices are also dangerous, the wind funnels through them and it
can speed up to 2-3 times of it's normal speed. In this situation the trike can be blown back
behind the mountain and may get into severe turbulence. The third danger of ridge soaring is
wind shear over the trees which tries to turn the trike into the forest. As Sparky recommends in
his book - I tried to visualize wind as water flowing across the mountains and it helped to see
the turbulent zones.
I always tried to be aware of the wind direction and often did 360 degree turns to map it out.
What the book writes is true - wind speed may be multiplied by the mountains. I was flying in
20kt winds aloft and clocked over 110+mph ground speed - while my trim speed is only 60mph.
Not considering the effect of density altitude it means 50+mph wind speed.
Other problem - there are no alternate routes. If the mountain pass is barely VFR or raining
along the route - there is no way to fly around it. This was the reason I spent a whole day on
the ground close to Yellowstone waiting for the rain to clear the pass.
Weather changes extremely fast in the mountains. I was sitting on the ground contemplating on
flying. Between two waves of the cold front a nice blue hole was moving along. I stayed on the
ground and in 5 minutes there were a few innocent looking cumulus clouds in the blue hole. In
30 minutes they merged and grew to a major cumulonimbus. I was so glad to be on the ground.
Sometimes the air is very smooth under the morning inversion as it blocks the rotors coming
from the mountains and it is worth flying low. But most of the time the saying is true - elevation
is your friend.
Quickly changing weather also means that it is best to fly short hops and have designated
emergency airports to land at. I had to use one of my emergency landing spots as the clouds
formed a solid wall in front of me with rain all the way to the ground. Flying in rain is not fun, it
reduces the plane's performance and comes with strong turbulent down-drafts that can go all
the way to the ground just like microbursts.
When flying through long mountain valleys I watch the weather behind me to make sure I do
not loose VFR and have the option to turn back. When you enter the mountains you can
never be sure what the weather will look like in two hours and 120miles down the valley.
In mountain flying the rule is to approach the ridges at a 45 degree angle. This enables the
pilot to turn back to lower ground. For trikes which can turn on a dime compared to GA I just
changed this rule to always have an escape route. I also considered the wind direction,
speed and possible turbulence when selecting escape routes and landing spots.
Forget the traffic pattern when landing on small mountain airfields. They are very rarely used
and the best pattern is that puts you down safely. Often they are tucked between mountains
with areas of rotors. The best is to drop through those rotors or keep the distance from the
hills and other rotor inducing objects.
Many mountain fields have a significant down-slope that is invisible from the air. Soft field and
cross wind landings and take-offs are also normal, often the direction of the landing strip is
dictated by the terrain and not by the usual wind direction. Check the density altitude on asos,
even trikes can feel sluggish at take off at 8500' DA.
On high plateaus the ground elevation is 3-4000ft, the cloud base is at 8000 and the top of the
clouds reach way over 10000ft. This means that a light sport plane can not climb over the
weather and has to fly in convective air. I found the best elevation to fly is where the thermals
kicking off the ground are already wider and smoother but the influence of the clouds are not
too strong yet. Flying along rivers may help, I found that the Snake River had a strong cooling
effect blocking the thermals.
The great thing about trikes - being exposed to the elements is also a disadvantage. One can
get very cold and exhausted after a few hours of wrestling with the turbulence. Paying attention
to your own well being is very important. Like on sailboats - one hand for yourself, one hand
for your boat (plane). I used up to 5 layers of polartech on top and three on bottom under the
pilot suite. I also made sure never get sweaty when on the ground so I spent a significant
amount of time adding and removing layers. A polartech sweater is about $80 at REI. I did not
want to spend that much so I got them from local thrift stores for less then $10 each... Since I
commute on a motorcycle I am used to cold, rain and wind and built up some tolerance to the
elements. Still at times I felt hypothermic when flying and was glad to land. Hypothermia
reduces the ability to think and stay focused.
My trike's endurance is not great when flying at high altitudes. The fuel consumption goes from
2.4Gal/hour to over 4Gal/hour as the rpm goes from 4000 to 5200 at level flight. The next
instrument I will install will be a fuel flow gauge which can give me a good endurance estimate.
One of my biggest weakness is my spotty weather knowledge. I will learn to read the clouds
better and understand the local and regional weather more. The available weather tools
provide an incredible array of information.
Convective air movement is multiplied by the mountains. I had 900ft/min lifts and similar sinks
along the way. Generally the plane can easily take these air movements and the pilot gets
tired first. For this reason I flew from the early morning and into the early afternoon until I got
too tired and had enough wrestling with the thermals. For my next trip I will install wingtip
position lights so I can fly in civil twilight.
If you were able to take this much "wisdom" in one reading - you must be a very dedicated trike
pilot. Please let me know if you have other or different experiences when flying in mountains.
These are a few photos of pretty clouds and other weather events I have
encountered along the way:
Cumulus congestus:
Mountain waves with layers of lenticulars:
Cumulonimbus, virga (rain):
Crest clouds:
Dirt Devils:
