Description of the decent through a wave hole and flight under the cloud deck through a ridge gap to land back at Sugarbush Airport.

Trace of C-FVKA's flight over Roxbury GapI was at 10 000 ft when the hole over Sugarbush airport started to close. I circled down with full dive brakes but by the time I reached the top of cloud at about 5000 ft, the gap above the airport was nearly closed and I had drifted down wind to be over Roxbury in the valley east of the airport.

Momentarily, I thought of trying for the small hole over the airport but realized that by the time I reached it, it would be closed and I would have dropped into cloud on the way. My only option was to descend through the hole over Roxbury and fly under the clouds to the airport 4 nautical miles (7.5 km) upwind. The base of the clouds was about 4000 ft. On the advice of a pilot who had just done the same thing, I stayed as near cloud base as possible as I headed under the cloud deck. Luckily, I had already positioned my self due east of the Roxbury Gap using its waypoint on my GPS.

My only worry was having enough height by the time I went through that gap in the East ridge. I was at just under 4000 ft about 2.2 nm from the gap flying upwind (I do not know what the windspeed was at the time). Diagram 1 shows my track and diagram 2 shows my barometric trace for that portion of my flight. The latter diagram view is such that you are seeing the flight from the north looking south. I have added the level of the terrain over which I flew to show ground clearances. I need not have worried since I made it over the gap with 800 ft to spare (It seemed much small at the time). I did not have a flight computer and at the time was concerned as to what the speed of best glide over the ground should be. At the beginning of the glide I was at 60 kts but that was too fast and I slowed

Analysis of my track shows that when I descended from 10000 ft the airspeed was about 62 kts and the drift of the circle indicated a 24 kt wind from the west. At 13000 ft the decending track indicates that windspeeds were 35 kts. The final few turns of my descending spiral indicate an airspeed also 62 kts but the wind is only 13 kts just above cloud level. Presumeably this is the headwind C-FVKA faced going back to the airport over Roxsbury Gap. The ground speed varied from 40-48 kts during this section of the flight with the speed increasing as I approached the Gap. The sink rate varied from -0.5 to -3.0 kts while overall glide slope over the ground was 19:1. If the headwind was 13 kts then I was flying from 53 to 61 kts airspeed.

If the Ka6e has a practical best glide of 30:1 and is flown at best glide airspeed (45 kts), then a 13 kt head wind would decrease the glide slope over the ground to (45 - 13)*30/45 = 21. However, as we see, I was probably too fast and that decreased my glide slope. It is here that a flight computer would have been very useful. But the time involved was short, only three minutes from hole edge to the Roxbury Gap. It seemed much longer in real time.

Barographic Trace of flight over Roxbury Gap