FAA is predicting that the piston aircraft market will continue a long slide over the next 10 years, and average a decline in aircraft fleet numbers and hours flown of 0.1% per year over the next 20 years.

At the same time, turbine business aircraft are expected to increase at an average rate of 2.9% per year, FAA says in its 20-year forecast that runs through 2032. Correspondingly, turbine aircraft hours are expected to pick up 4% per year, eclipsing the total number of annual piston hours by the end of the forecast period.

Overall, FAA expects the general aviation fleet to increase from 222,520 in 2011 to 253,205 in 2032, averaging to about 0.6% per year. Hours flown are expect to grow overall at a rate of 1.7% per year, from an estimated 24.4 million in 2011 to 34.8 million in 2032.

FAA predicts piston aircraft will drop from the 2010 total of 159,007 to 151,685 through 2023, with declines in both single and multi-engine fixed wing aircraft. The number of active piston aircraft is expected to increase beyond 2023, but only growing to 155,395 by 2032.

A major driver for the lowered piston-aircraft forecast is a change in the assumptions FAA uses in its forecast. “At a Transportation Research Board meeting with industry and academic experts, we heard pretty loudly from all experts that what we were forecasting was simply too high,” the agency says. “There are a lot of single engine piston aircraft that are getting older, and older aircraft fly less, and they are dropping out of the fleet.”

FAA does expect replacements. “As new aircraft come out, the hours will start to pick up again,” the agency says, but notes that the general aviation market faces plenty of competition for leisure time.

But FAA also sees increased use of piston aircraft for business purposes, alongside business turbine aircraft.

FAA notes that recent shipment activity “indicates cautiously optimistic results that the hard impact of the recession on the business jet market may have come to an end and demand for business jet aircraft is beginning to recover.” The agency points to higher corporate profits and growth of worldwide GDP as drivers behind the improvements in the business jet market. “Additionally, continued concerns about safety, security, and flight delays keep business aviation attractive relative to commercial air travel,” FAA says.

FAA also sees continued growth in the new light-sport category, which was recognized beginning in 2005. The number of LSAs had grown to 6,528 by the end of 2010, and FAA believes the category will grow at a 4% rate through 2013 and then slow to 2% annually per year for a total of 10,195 by 2032.