The attitude indicator shows a descending 60-degree-bank to the right. The directional gyro shows your heading off slightly but in the opposite direction. You can't see the horizon, but your compass and all the other flight instruments indicate straight and level.
The diagnosis: pneumatic systems failure, which can be terrifying or even catastrophic when flying at night or in the clouds.
The AOPA Air Safety Foundation's latest minicourse, Pneumatic Systems, describes both pressure and vacuum systems and teaches the early warning signs of system failure. It also discusses options for system redundancy and the common causes of failures, as well as what a pilot can do to prevent them.
June 28, 2006