FAA has revised its annual aviation forecast to reflect a much slower demand recovery than previously expected, although load factor growth continues to surprise.

Projections in the 20-year forecast show there won’t be a “rapid recovery [or] snap-back” to pre-downturn levels, agency officials said. FAA is seeing “no sign of the pent-up demand” that has been a precursor to rapid recoveries seen in the past.

The agency now predicts U.S. airlines will carry one billion passengers a year by FY2023 – two years later than in last year’s forecast, and seven years later than the 2008 prediction.

Last year, FAA forecast 2% growth in domestic enplanements for FY2010, and 2.4% for international. This estimate has been scaled back, and the agency now expects domestic enplanements to grow 0.4% in FY2010, with international numbers up 0.9%.

For the remainder of the 20-year forecast period, domestic and international enplanements are predicted to rise by 2.5% and 4.1%, respectively. While short-term increases are lower than in last year’s forecast, the longer-term growth rates are similar.

Systemwide capacity is now expected to drop by a further 1.6% this year, versus the 2.6% growth predicted last year. Capacity is set to increase 2.5% in FY2011, and grow by an average of 3.4% a year for the forecast period.

Agency analysts “continue to be amazed” at the steady growth of load factors, which are being pushed up by a combination of flat demand and lower capacity. Last year, FAA predicted system load factor would be essentially flat in FY2010. But now it sees loads rising another 1.6 points to top 81%.

There was a sharp decline in yield – in real terms – in FY2009, but FAA expects to see domestic and international mainline yield increase 1.6% and 3.1%, respectively, in FY2010. Over the 20-year forecast period, real yields will decline by an average of 0.9% a year as competitive pressure keeps prices down.

Meanwhile, aircraft operations at towered airports are predicted to decrease by 2.7% to 51.5 million in FY2010, and then grow at an annual average rate of 1.5%. Commercial operations are expected to drop 2.2% in FY2010 and then rise 1.9% a year, with general aviation down 3.1% in FY2010 before increasing by 1.3% a year through FY2030.