Performance Theory & Jet Engine Performance

Why are there performance regulations?

So there is an acceptable level of safety

What is an acceptable probability?

10^-6, once in every one million flights

What are the different categories of accidents?

Minor (likely)

Minor (unlikely)

Major

Hazardous

Catastrophic

What is measured performance?

Average performance, aircraft of the same type under test conditions

What is gross performance?

Average performance, fleet of newish aircraft, same type, operated by average pilots (50/50)

What is net performance?

Gross performance plus an increment (safety)

What are unqualified gross distances?

Aircraft measurement

- TOR

- TOD

- ASD

What are available distances?

Runway measurement

- TORA

- TODA

- ASDA

What are required distances?

An aircraft measurement

- TORR

- TODR

- ASDR

How do thrust and SFC change with altitude?

They decrease as altitude increases (effect of pressure greater than effect of temperature)

How do thrust and SFC change above the tropopause?

Thrust continues to decrease (constant temperature, decreasing pressure) while SFC is constant

What is flat rating and why is it done?

Thrust is constant with increasing temperature until Tref (when it decreases)

For

- Avoiding excessive wear

- More constant performance

What is Tref?

The reference temperature at which lower than that still produces a constant thrust (like thrust reduction)

What are the TOGA limits?

Takeoff Go Around thrust

- AEO is 5 mins

- OEI is 10 mins

What is MCT?

Maximum Continuous Thrust

What is CRZ?

Maximum Cruise Thrust

What is CLB?

Maximum Climb Thrust