AFH Chapter 4-30 Environmental Factors

Environmental Factors

Turbulence, or a large variation in wind velocity over a short distance, can cause upset and LOC-I.

 

Maintain awareness of conditions that can lead to various types of turbulence, such as clear air turbulence, mountain waves, wind shear, and thunderstorms or microbursts.

 

In addition to environmentally-induced turbulence, wake turbulence from other aircraft can lead to upset and LOC-I.

 

Icing can destroy the smooth flow of air over the airfoil and increase drag while decreasing the ability of the airfoil to create lift.

 

Therefore, it can significantly degrade airplane performance, resulting in a stall if not handled correctly.

 

Mechanical Factors

Modern airplanes and equipment are very reliable, but anomalies do occur.

 

 

Some of these mechanical failures can directly cause a departure from normal flight, such as asymmetrical flaps, malfunctioning or binding flight controls, and runaway trim.

 

Upsets can also occur if there is a malfunction or misuse of the autoflight system.

 

Advanced automation may tend to mask the cause of the anomaly.

 

Disengaging the autopilot and the autothrottles allows the pilot to directly control the airplane and possibly eliminate the cause of the problem.

 

For these reasons the pilot must maintain proficiency to manually fly the airplane in all flight conditions without the use of the autopilot/autothrottles.

 

Although these and other inflight anomalies may not be preventable, knowledge of systems and AFM/POH recommended procedures helps the pilot minimize their impact and prevent an upset.

 

In the case of instrument failures, avoiding an upset and subsequent LOC-I may depend on the pilot’s proficiency in the use of secondary instrumentation and partial panel operations.