Performance Margins

At one time or another, weve all passed an FAA knowledge test requiring us to calculate aircraft performance for various phases of flight, such as takeoff, cruise and landing. Even though weve been trained and tested on our ability to interpolate the answer down to the foot, mile, minute or gallon, these calculations alone dont ensure were always operating the aircraft prudently. For one thing, they dont account for poor technique, worn equipment or errors.

Robert Wright

Friday, April 21, 2017 at 12:00 AM ET

Verified

Key Takeaways:

Standard aircraft performance calculations from the Pilot's Operating Handbook (POH) are insufficient for safe operation alone, as they often fail to account for real-world variables, pilot technique, equipment issues, or environmental factors like density altitude and runway surface conditions.
Pilots must actively establish "performance margins" or "fudge factors" and practice comprehensive risk management to compensate for these imperfections and ensure safety across all flight phases (takeoff, climb, and landing).
Many pilot-related accidents, particularly during takeoff and landing, result from inadequate performance analysis and a failure to build in additional safety factors, ignoring environmental and aircraft-specific risks.
Unlike transport category aircraft, Part 23 certified light twins do not guarantee safe engine-out takeoff performance, requiring meticulous accelerate-stop/go distance calculations and significantly longer runways than might initially be perceived for adequate safety margins.

See a mistake? Contact us.

At one time or another, we’ve all passed an FAA knowledge test requiring us to calculate aircraft performance for various phases of flight, such as takeoff, cruise and landing. Even though we’ve been trained and tested on our ability to interpolate the answer down to the foot, mile, minute or gallon, these calculations alone don’t ensure we’re always operating the aircraft prudently. For one thing, they don’t account for poor technique, worn equipment or errors.

Effective risk management requires us to go further and build in what some might call a fudge factor, something that, for example, helps us compensate for less-than-perfect technique. We can do that in various ways, including regular training and practicing maximum-performance takeoffs and landings, carrying more fuel, opting for the longest runway available and avoiding non-cooperative weather. Whether we realize it or not, we establish safety margins, allowing us to err in performing the maneuver or its calculations yet still complete the operation. I call them performance margins.