by John Mader, P. Eng., ATPL, Class 1 Instructor, Calgary Flying Club
Flying through the mountains on a beautiful day is one of the great joys that we who are able to fly can experience. Like all other flying, mountain flying has associated risks, and doing so safely is a matter of identifying the hazards and either avoiding them or mitigating them so that the remaining risk is at an acceptable level. Knowing when not to go flying in the mountains is an important skill to develop.
By far the biggest risk area in mountain flying is the weather. Mountain topography itself plays a large part in this, as orographic lift, resulting in cloud and precipitation, can form whenever moist air crosses a mountain range, regardless of direction. Often, fair weather on the east side of the range will be accompanied by poor weather on the west side, and vice versa. Ideal weather occurs when a large, dry, high-pressure system covers the range, with low-pressure gradients giving light winds.
One of the challenges in developing a clear picture of the weather situation is the lack of weather reporting stations in mountainous areas and the variability of weather along any particular route. For example, if planning a flight from Calgary Springbank to Kamloops on collaborative flight planning services (CFPS), the only weather reporting stations that will come up in between are at Golden and Revelstoke, and neither of these have terminal forecasts. Public forecasts can help, but they often lack information like ceiling. Often, webcams along your planned route can be a great help in checking current weather. Make sure they are operating properly, however, and that you are not looking at a frozen picture from last week. Satellite images that can be selected from CFPS can also help in determining cloud cover along the route. Flight information centre (FIC) personnel can help with this, as they reportedly have access to better resolution images than are available on CFPS.
Expected turbulence should play a big role in determining your go/no-go decision. Nothing will turn off a passenger from ever flying with you again more than having to endure long stretches of turbulence waiting for the next airport to arrive. So, check the turbulence graphical forecast area (GFA) to see if any mountain wave is predicted, and check the winds at peak top level. In the Calgary area, this means the 9 000 and 12 000-ft levels. The rule of thumb used here is that if the winds at peak top level are forecast 25 kts or more, cancel your trip for today. If the winds are 20 to 25 kts, it may be okay for experienced flyers, but non-pilot passengers are probably not going to like it.
When flying in the mountains, make sure that you plan things so that you will be safely tied down at destination before dark. Flying at night single-engine visual flight rules (VFR) in the mountains is just a bad idea. Be aware that even before darkness falls, westbound flying may have poor visibility due to glare from the setting sun and growing darkness after the sun sets. It may be difficult to see obstacles, even though it is not yet night.
Arial view of the mountains on a clear day.
Credit: John Mader
It may not be obvious in the mountains with so much rock above you, but some mountain airfields can be at quite high altitudes. This, plus high summer temperatures, means high-density altitudes. Transport Canada defines density altitude as pressure altitude corrected for non-standard temperature. I prefer a definition that I think is a bit more meaningful:” Density altitude is a measure of air density, expressed as an equivalent altitude in the ICAO Standard Atmosphere.” In Springbank in the summer, with temperatures in the +30°C range, we frequently have density altitudes above 6 500 ft. In other words, your airplane will act like it is above 6 500 ft in the standard atmosphere. This means lower engine power (unless turbocharged or supercharged), longer takeoffs and landing runs, lower climb rates and larger turning radii. Take this into account when planning landings and takeoffs at mountain airfields. In some cases, it may be better to reduce load and wait for cooler temperatures or more favourable winds before taking off. In addition, since most light aircraft need more room to take off than to land, make sure you don’t land at an airfield you won’t have enough room to take off from.
Pick your routings to reduce your risk in the event of mechanical problems. Aircraft engines are very reliable, as long as you give them fuel, air and ignition, but sometimes they do fail, and I would rather not be a long way from civilization if that happened. My preference is to stay within gliding distance of major roadways, just in case. If you can’t land on the road, you can usually find some smaller trees beside the road, and help is more likely to be near. Also, consider taking survival gear with you when flying through the mountains.
Safe flying through the mountains also means having alternate plans and routes, should things not turn out as planned. Think about where else you could go, should your route to destination be blocked. Would you have sufficient fuel to get there? What if you had to go all the way back to your departure point from almost getting to your destination? Would you have the fuel to do that? Often there are few or no aerodromes along your route where fuel is available. Think these issues through ahead of time. Even if the Canada Flight Supplement (CFS) says there is fuel available at an aerodrome, it is a good idea to call the supplier and make sure of availability before you go.
Arial view of the mountains on a clear day.
Credit: John Mader
With the popularity of GPS and Foreflight, getting lost in the mountains is becoming less and less likely. However, I still believe that charts are the ultimate backup, and knowing how to map read is an essential basic skill. Checking your charts beforehand can help you identify alternate routes to use if, for example, a thunderstorm is blocking your way. Making sure you always know where you are can help you avoid inadvertently turning up the wrong valley.
Flying through the mountains on a day with great weather can be an exhilarating experience for you and your passengers. Preparation, hazard identification and risk mitigation are the keys to a safe and successful trip. Pick your days and never commit to making a particular trip on a particular day. I have given mountain checkouts that have been done on the first try and others that had to be cancelled five times before we finally got a good day. Be patient and take your time. And if you have never flown in the mountains or would like to improve your skills, contact any flight school near the mountains, and they will be able to help you safely transition into mountain flying.