Identify the two reduced-thrust climb selections shown on the N1 LIMIT page.

• A. CLB 1 is approximately a 10% derate of climb thrust and CLB 2 is approximately a 20% derate of climb thrust
• B. CLB 1 is approximately 5% derate and CLB 2 is approximately 10% derate
• C. CLB 1 is approximately 15% derate and CLB 2 is approximately 25% derate
• D. CLB 1 is approximately a 20% derate and CLB 2 is approximately a 30% derate

Answer: (A)

On the N1 LIMIT page, two reduced-thrust climb options are shown as CLB 1 and CLB 2. These settings derate the climb thrust from the maximum value to keep engine N1 within safe limits while maintaining a usable climb performance. The values for this airplane put CLB 1 at about a 10% derate and CLB 2 at about a 20% derate. In practical terms, CLB 1 uses roughly 90% of the full climb thrust, while CLB 2 uses about 80%. The lighter derate preserves better climb rate and acceleration, while the heavier derate saves more fuel and reduces engine load at the expense of a slower climb. The specified amounts are the standard representations you’d see on the N1 LIMIT page for these two selections.