Turbulence Penetration

Question 1

Define Light Turbulence

Answer 1

Slight changes in attitude/altitude, changes in IAS of 5-15kts

Question 2

Define Moderate Turbulence

Answer 2

Similar to light turbulence, but greater intensity.

16-25kts fluctuation in IAS but aircraft remains in positive control.

Question 3

Define Severe Trubulence

Answer 3

Abrupt changes in attitude/altitude.

Momentarily out of control.
≠25kts fluctuation in speed.

Occupants forced against seatbelts, unsecured objects thrown about.

Question 4

What are suggested actions for light/moderate turbulence?

Answer 4

Seatbelt signs on

Verify CON in FMC N1 limit.

Question 5

What mode should never be used in severe turbulence?

Answer 5

ALT HLD.

Question 6

Actions for severe turbulence?

Answer 6

Disengage autothrottle. Set FMC TURB N1. Don’t chase the airspeed.

Start switches - FLT

Maintain wings level / pitch attitude.

Don’t change stabiliser trim or use large control inputs.

Don’t change the altitude.

Sacrifice altitude for attitude and airspeed.

Question 7

What is the optimum speed for climb/descent during severe turbulence?

Answer 7

280kts / M.76.

If below 15000ft, can slow down to 250kts.