| Home | Privacy | Contact |

Pilot's Handbook of Aeronautical Knowledge
Aircraft Performance
Performance Speeds

| First | Previous | Next | Last |

Pilot's Handbook of Aeronautical Knowledge

Preface

Acknowledgements

Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making

Appendix

Glossary

Index

That is the original estimate of 1,600 under planned
conditions plus the additional 640 feet for excess speed
and the tailwind. Given the pilot overshot the threshold
by 1,000 feet, the total length required is 3, 240 on a 3,500
foot runway; 260 feet to spare. But this is in a perfect
environment. Most pilots become fearful as the end of the
runway is facing them just ahead. A typical pilot reaction
is to brake—and brake hard. Because the aircraft does not
have antilock braking features like a car, the brakes lock,
and the aircraft hydroplanes on the wet surface of the runway
until decreasing to a speed of about 54 knots (the square
root of the tire pressure (√36) x 9). Braking is ineffective
when hydroplaning.

The 260 feet that a pilot might feel is left over has long since
evaporated as the aircraft hydroplaned the first 300–500 feet
when the brakes locked. This is an example of a true story,
but one which only changes from year to year because of new
participants and aircraft with different N-numbers.

In this example, the pilot actually made many bad decisions.
Bad decisions, when combined, have a synergy greater
than the individual errors. Therefore, the corrective actions
become larger and larger until correction is almost impossible.
Aeronautical decision-making will be discussed more fully in
Chapter 17, Aeronautical Decision-Making (ADM).

Performance Speeds

True Airspeed (TAS)—the speed of the aircraft in relation to
the air mass in which it is flying.

Indicated Airspeed (IAS)—the speed of the aircraft as
observed on the ASI. It is the airspeed without correction
for indicator, position (or installation), or compressibility
errors.

Calibrated Airspeed (CAS)—the ASI reading corrected for
position (or installation), and instrument errors. (CAS is
equal to TAS at sea level in standard atmosphere.) The color
coding for various design speeds marked on ASIs may be
IAS or CAS.

Equivalent Airspeed (EAS)—the ASI reading corrected
for position (or installation), for instrument error, and for
adiabatic compressible flow for the particular altitude. (EAS
is equal to CAS at sea level in standard atmosphere.)

Vso—the calibrated power-off stalling speed or the minimum
steady flight speed at which the aircraft is controllable in the
landing configuration.
Vs1—the calibrated power-off stalling speed or the minimum
steady flight speed at which the aircraft is controllable in a
specified configuration.
Vy—the speed at which the aircraft will obtain the maximum
increase in altitude per unit of time. This best rate-of-climb
speed normally decreases slightly with altitude.
Vx—the speed at which the aircraft will obtain the highest
altitude in a given horizontal distance. This best angle-of climb
speed normally increases slightly with altitude.
Vle—the maximum speed at which the aircraft can be safely
flown with the landing gear extended. This is a problem
involving stability and controllability.
Vlo—the maximum speed at which the landing gear can
be safely extended or retracted. This is a problem involving
the air loads imposed on the operating mechanism during
extension or retraction of the gear.
Vfe—the highest speed permissible with the wing flaps in a
prescribed extended position. This is because of the air loads
imposed on the structure of the flaps.
Va—the calibrated design maneuvering airspeed. This is
the maximum speed at which the limit load can be imposed
(either by gusts or full deflection of the control surfaces)
without causing structural damage. Operating at or below
maneuvering speed does not provide structural protection
against multiple full control inputs in one axis or full control
inputs in more than one axis at the same time.
Vno—the maximum speed for normal operation or the
maximum structural cruising speed. This is the speed at
which exceeding the limit load factor may cause permanent
deformation of the aircraft structure.
Vne—the speed which should never be exceeded. If flight is
attempted above this speed, structural damage or structural
failure may result.
 

10-17