Archive for September, 2012

Too Short?

Thursday, September 6th, 2012

There are some immutable laws of physics that come into play when we fly. One of them that really should be respected is the landing distance required. There was an accident last week at Falmouth Airpark (5B6) on Cape Cod, Mass., involving a Cirrus SR22, a young CFI, a student pilot, and his wife. My usual caveat applies that this is perhaps slightly educated speculation on what happened since the NTSB factual report is months away.

The SR22 is a high-performance aircraft with a high wing loading and relatively high stall speeds. Most aircraft are able to land at an airport but then may be unable to take off in the available distance. The Cirrus is one of the few where the opposite is true—it needs more runway to land than to get airborne.

According to the SR22 Pilot Information Manual, under standard day, sea-level conditions, which would be close to those at 5B6, the landing distance to clear the 50′ obstacle is 2,636’ at a speed of 78 knots with additional speed added for wind as needed. The runway is just under 2,300′ and about 40′ wide which doesn’t allow much maneuvering in a crosswind. As can be seen in the photo, there’s not a lot of overrun, and most of us typically will clear the obstacle by at least 20′.

Short, narrow runway, perhaps some gusty winds, and pilots with unknown experience add up to a very high-performance situation. The Air Safety Institute recommends starting with a 50% margin over the best the test pilots can do during certification with a brand new aircraft using maximum braking. Call it 2,600′ plus 1,300′ equals just shy of 4,000′.

The epilogue, for what appears to be a slight miscalculation, is the 24-year old CFI was fatally injured, and the student and his wife were severely injured. This is not always a benign activity, and it’s good to remember that.