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PilotSchool Knowledge Base

Understanding Flap Speeds

Introduction

In the realm of basic aeronautical knowledge, especially concerning aircraft operations and performance, it’s crucial to understand the limitations associated with flap usage during flight. Two key terms in this context are Flap Extended Speed (VFE) and Flap Operating Speed (VFO). This section aims to elucidate these concepts relevant to pilots under the CASA RPL (Recreational Pilot License) framework.

Flap Extended Speed (VFE)

Definition

Flap Extended Speed (VFE) is the maximum speed at which an aircraft can be safely flown with its flaps fully extended. This speed is significant for preserving the structural integrity of the aircraft during operations with extended flaps.

Characteristics

  • Display: VFE is typically displayed on the Primary Flight Display (PFD) when the slats or flaps are extended.
  • Determination: The value of VFE is determined by the structural limit speed for specific flap configurations, incorporating a safety margin tailored to each aircraft model.
  • Availability: VFE is listed on the aircraft’s speeds placard, located in the cockpit.

Implications

Operating an aircraft above its VFE while the flaps are extended can lead to structural damage or potential flap loss. Exceeding this speed compromises the aircraft’s safety and performance.

Speed Variability

The VFE is not uniform across all flap settings and varies by aircraft model. For instance:

Sources

Flap Operating Speed (VFO)

Definition

Flap Operating Speed (VFO) indicates the maximum speed at which an aircraft can be safely operated while the flaps are transitioning — moving to or from the extended position — rather than being fully extended.

Characteristics and Implications

While VFO is not universally detailed in flight manuals, it is understood to be significant in maintaining safe operational practices during phases when the flaps are not fully retracted or extended Part 61 MOS Schedule 3 - CASA.

Considerations for Pilots

Understanding the differences between VFE and VFO is crucial for ensuring operational safety, particularly during takeoff and landing phases when flap settings are actively managed. Aspiring pilots are encouraged to consult their specific aircraft’s Pilot Operating Handbook (POH) or Aircraft Flight Manual (AFM) for accurate information on these speeds.