Hot, High and Heavy in Penticton

by Gerhard Schauble, CPL (A), SMELS, GL25, IR, Penticton, B.C.

aerial view

Photo © Mike Biden

Penticton Regional Airport (CYYF) is an absolute jewel in British Columbia. It is ideally located on VFR routes to the Pacific coast, the B.C. interior and Alaska. Recent crashes of aircraft departing from CYYF have begged the question, “why?”  While the accidents are under investigation by the TSB and we recognize that there are complex issues in determining the cause of aviation accidents, several of the accidents share common threads. These flights

  • departed from Penticton;
  • departed in the afternoon on a clear, hot summer day;
  • departed with full fuel and four persons on board;
  • flew over mountainous terrain; and,
  • terminated when the aircraft flew into terrain.

The best source of information about local weather, navigation and specific airport nuances is often local pilots. So, on an August afternoon in Penticton, a group of experienced mountain pilots sat in the shade of a hangar and shared their thoughts on “why?” with a view to preventing similar accidents.

Density altitude: We learned about it in ground school. It is commonly referred to as the actual altitude at which the plane “feels” like flying. The pilot examiner in the group tells us that candidates will answer density altitude questions correctly but often seem surprised by the lack of performance in the air. For instance, it is 5:00 pm on a mid-August day at CYYF. Field elevation is 1 130 ft. It is the hottest time of the day, at 32ºC. Dew point is 11ºC. Clear skies with visibility at 15 SM. Winds out of the north at 7 kt. Barometric pressure is 29.86.  It is a typical Penticton summer day. Perfect, right? Well, we haven’t left the tie down area and density altitude has already placed our aircraft at 3 562 ft.
Density altitude will sap power from your engine. It can eliminate any chance of a climb rate on departure. Density altitude not only affects the take-off distance and rate of climb, but it also applies to the service ceiling of the aircraft while flying en route. It may be possible to fly your aircraft with a service ceiling of 12 650 ft toward the mountains near Princeton that top out at 10 000 ft, yet because of density altitude the aircraft is unable to clear the mountains.

Weight: In a typical light aircraft, you have four seats, a baggage compartment and fuel tanks. Fill them and your aircraft will be overloaded. This creates the following problems:

  • the aircraft will need a higher take-off speed, resulting in a longer take-off run;
  • both the rate and angle of climb will be reduced;
  • the service ceiling will be lowered;
  • the cruising speed will be reduced;
  • the cruising range will be shortened; and,
  • manoeuvrability will be decreased.

Mountain flying: It is different out here. It is different from the prairies and it is different from the coast. Mountain flying requires specific decision-making challenges resulting from the mountain flying environment, mountain weather trends, density altitude, pre-flight planning and preparation, take-off and departure techniques, and approach and landing considerations.
We have mountainous terrain on all sides of Penticton; the beauty is unsurpassable but requires our respect. Route planning is critical and GPS direct navigation to and from Penticton may not be the best way to go. Pick a route that avoids the rugged areas and highest peaks, where an emergency landing cannot be made. It usually takes little extra time to bypass the most mountainous areas and follow the designated VFR routes through lower terrain.

Let’s go flying! Let’s go back to that mid-August day. Let’s pull out that rental, top it up with fuel and invite three of our buddies. Our take-off roll into wind on Runway 34 takes us past the terminal building. Our rate of climb is 200 fpm. We call clear of the zone over Trout Creek Point in Summerland and decide to continue north, because, at this rate of climb, we haven’t cleared the valley ridge on the west side of Lake Okanagan yet. Somewhere between Summerland and Peachland we gain enough altitude to clear the valley ridge and set our course on a GPS heading to the west. At some point it becomes clear that we cannot out climb the next ridge, that we don’t have enough altitude to turn away from the ridge, and that we have left ourselves no options.
So, let’s rewind this video. Before departing Penticton on a hot summer day:

  • take a mountain flying course with a qualified instructor, or, at the very minimum read Sparky Imeson’s book Mountain Flying, prior to arriving at Penticton;
  • know the density altitude, the field elevation, the temperature and the wind speed and direction;
  • know your aircraft weight and performance limitations;
  • know when and why you should abort the takeoff; 
  • fly as light as possible; 
  • consult your VFR charts, plan your flight, and do not rely solely on GPS navigation;
  • plan to cross ridges at 45º and at least 1 000 ft above the ridges;
  • depart in the cooler time of day, preferably early morning; and,
  • on departure climb to cruise altitude before departing the valley.

Fly safe and come back to visit us in Penticton.

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