Jul 4, 2021
While New Zealand is often appreciated for its stunning mountain ranges and pristine alpine valleys and lakes, this picturesque landscape also makes for an exciting and challenging learn-to-fly environment for prospective pilots.
New Zealand’s North Island provides somewhat limited mountain flying seeing as there is only a couple of fairly standalone mountains, it’s the South Island offers a wide variety of varied terrain amongst the majestic mountain range – the Southern Alps.
4 Basic Factors Of Mountain Flying
Mountain flying training is a requirement for obtaining your Commercial Pilots Licence in NZ, and greater terrain awareness is necessary for your PPL, so it is essential to get a good grasp of the basics of mountain flying. There are four essential elements to building greater terrain awareness and improving mountain flying techniques. Pilots need to master each of the factors equally.
The restrictive size and shape of New Zealand commonly dictates relatively low altitude flying, which means the weather strongly influences almost all types of flight operations. This is why it is essential to undertake an extensive weather briefing before departure and keep a close watch on weather conditions in-flight.
Perhaps the one thing you can count on when flying through mountains is that the weather is prone to rapid and sometimes violent changes. The visibility, external temperatures, turbulence patterns, and wind shear can all significantly alter multiple times over the course of the flight path.
NZ’s mountainous terrain can vary from immense peaks and deep shadow clad valleys through to alpine lakes, deep winding rivers, steep gorges, and tree and tussock covered hills. There are considerable variations in altitude, ground cover and geological structure, all with different effects on the principles of flight.
Often the size, slope and elevation of the geographical conditions of mountainous terrain can be difficult to judge due to the lack of visible horizon, glare and low flying altitudes. The pilot must take into account these variances to safely navigate through the mountains.
3. Aircraft Performance
Under mountain flying conditions, the reactions, capabilities and responses of an aircraft can be significantly distorted. This means the aircraft may not perform in the way that pilots are used to under routine flight.
Fully understanding your aircraft performance capabilities and limitations is critical when mountain flying. This includes turning radius, load configuration, speeds, and density and pressure adjustments.
4. Pilot Skills
Traditional low flying training does not adequately prepare pilots for flying in the more demanding weather and terrain conditions of mountain flying. Lack of flight training and awareness in the mountains is proven to lead to a higher risk of accidents.
Decision-making and situational awareness are absolutely vital skills for any mountain flying. Pilots must master the ability to make sound in-flight decisions drawing on specialised training and flight experience while forming an assessment of current flight conditions.
Mountain Flight Pilot Skills
Some of the specific skills pilots need to master under a qualified flight training instructor are:
- Aircraft Performance, Engine Management and Cooling
- Valley Flying, Turns in Confined Areas
- Saddle crossings, Ridge Crossings
- Horizon Orientation
- Disorientation and Illusions, Sun Glare and Shadows
- Weather Interaction and Analysis
- Low-Level Navigation, Adequate Terrain Clearance
- Flight Emergencies and Survival Equipment
- Route Planning
- Abort or Continue Decision Making
- Short Field Techniques
- Crosswind Mountain Flying Techniques
6 Biggest Risks Of Mountain Flying
While many factors influence the safety of mountain flying, there are a few common reasons why things go wrong. Take a look below for our top 6 biggest risks associated with mountain flying in New Zealand.
1. Pilot Error
The single most common factor for accidents occurring during flight in mountainous terrain is the failure of the pilot to make sound decisions. This includes when to turn back if encountering deteriorating weather conditions, counteracting severe turbulence, succumbing to hypoxia or losing situational awareness.
2. Changes In Density Altitude
High density altitude and its effects on aircraft performance are among the most dangerous risks of mountain flying. Higher density altitude means the air is ‘thinner’, which means serious adjustments in aircraft control for pilots. This can include longer take-off and landing roll, reduced climb performance and less lift and thrust. Flying at higher density altitudes requires much greater attention to detail whether you are a trainee pilot or a seasoned professional.
3. Mountain Airports
Sloping runways are typical in mountainous terrain, as is taking off downhill/landing uphill and/or on a grass runway. A pilot needs to understand the differences these conditions will make to flight to be able to adjust calculations of aircraft performance.
4. The Weather
Adverse weather conditions are one of the most significant risk factors in mountain flying. Mountains generate unpredictable weather patterns with rapidly changing conditions. A pilot must know where areas of dangerous turbulence, downdrafts, and wind shear are likely to be found in order to avoid these risks.
5. Changes In Elevation
The rate of change in terrain in mountainous areas is highly variable; valleys can be narrow with limited visibility or wide and obstructed, unseen dead ends are common, along with abrupt changes in ridge heights. Understanding the terrain you are about to fly through is a critical component of planning safe mountain flying. Always ensure that the elevation changes on the planned route are within the performance capabilities of the aircraft.
6. Distorted Ambient Lighting
Large shaded areas due to steep peaks and shape inclines can disguise the presence of an obstruction such as a hill or outcrop that does not conform to the terrain expectation is one of the biggest causes of collision in mountain flying. This situation is most likely to occur when flying towards the sun as a result of increased glare and the additional contrast between shaded and non-shaded terrain.
10 Tips For Mountain Flying
While mountain flying can be a rewarding experience it is important to be prepared for all possible situations. Test your knowledge here with our top 10 mountain flying tips.
- Obtain Qualified Mountain Flying Instruction. Always choose flight training from a reputable and qualified instructor or flight training school.
- Make Turnback Decisions Early. Do not continue into deteriorating weather, do not rely on aircraft performance and do not wait until it is too late. Using your common sense will usually keep you out of trouble.
- Prepare And Plan. For the weather, for the terrain, for the changes in density altitude and most of all for the possibility something might not go according to plan!
- Always Have An Escape Route. Similar to the concept of defensive driving, when mountain flying, it’s essential to plan for evasive manoeuvres continuously. Always have a Plan B!
- Pack Survival Equipment. You never know what’s going to happen, and it always pays to be prepared. Include distress signalling devices, a medical kit, and enough warm clothing, food and water for each passenger.
- Fly Early In The Day. As a general rule of thumb in aviation, adverse wind and turbulence conditions are likely to be less of a factor earlier on in the day. At the same time, if leaving later in the day, ensure you have enough time to get there before the sun sets.
- Don’t Fly In The Bottom Of The Valley. Always fly partway up one side of a valley as this allows you to take advantage of updrafts and gives more room to manoeuver, providing better evasive options if need be.
- Always Maintain Situational Awareness. Do not try to make what you see out the window ‘fit’ the map. This can lead to misjudgement of your position and an increased chance of collision. If you are uncertain of your location, the safest option is to turn back.
- Understand The Limitations Of Your Aircraft. Always ensure the elevation changes along the planned route are within the performance capabilities of your aircraft. And remember to factor in the effects of density altitude.
- Obtain A Comprehensive Weather Briefing. Before setting out, always make sure you are well aware of the weather you are likely to encounter. Importantly, ensure the lowest ceiling is at least 2000 feet more than your highest planned ridge crossing.
If you are interested in finding out more about mountain flying or flight training in New Zealand, get in contact with Southern Wings Flight School for hands-on mountain flight training so that you can put the concepts discussed in this post into practice!
**Please note the information provided in this post is designed as a general guide only; it is not intended to replace professional mountain flying advice from a qualified flight instructor.