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Performance Fundamentals

Flight Performance - Lesson 1

· Education

Introduction:

Modern aircraft are designed and built according to strict standards which are laid down by national and international authorities to conform with ICAO Annex 8 (Airworthiness). In Europe, aircraft design must conform to EASA standards.

Aircraft manufacturers publish full details of aircraft performance in the Aeroplane Flight Manual (AFM), together with the approved aircraft operating technique necessary to achieve AFM performance.

Aircraft must be able to operate safely throughout their flight regime in such a way that a safe outcome will result from specified malfunctions (e.g. power unit failure), occurring at any point throughout the flight range.

When we speak of aircraft performance we’re usually answering three basic questions:

- How much can I haul ?

- How far can I go ?

- How long will it take me ?

It sounds simple but a specific set of interdependent variables must be considered in

order to answer each of these questions. Most of these variables have to do with aircraft

performance.

Weight and Balance

A good way to plan a flight is to decide how much weight you want to haul to what destination.

Start with the crew and passengers. Then add cargo.

If these items alone exceed your aircraft’s capability, you’ll either have to make multiple trips,

or get a bigger aircraft.

Once you know how much you want to haul, you can figure out how much fuel you can take, and

that, together with your weather information, will tell you how far you can go. If you have enough to

get to the destination plus alternate and reserve, you’re golden. If not, you’ll have to plan an en route

fuel stop.

We are going to go through this better futher.

Take-off and Landing Performance

The maximum aircraft mass at take-off must is the maximum mass calculated for the aircraft type, the runway elevation, length, slope and braking action, and the prevailing weather conditions such that the aircraft can:

  • Maintain specified minimum rates of climb after take-off with full power and with one power unit inoperative;
  • If a power unit failure is detected during the take-off run, either:
    • abandon the take-off and stop within the runway length; or,
    • continue the take-off, clearing all obstacles during the climb-out path by a specified margin.
  • Continue the flight with one engine inoperative, either returning to the departure airfield, the destination, or a specified alternate airfield clearing all terrain en-route by specified margins.
  • Land safely at the departure airfield, the destination or the specified alternate airfield.

The correct operating technique requires the aircraft to be flown at specified configurations, power settings and speeds corresponding to the actual aircraft mass throughout the take-off, initial climb, approach, and landing. (Configuration refers to the number of power units operating, whether flaps, landing gear or speed brakes are extended, etc.).

En-route Performance

The manufacturer specifies the maximum operating altitude when full power is available and also when operating with one or more engines inoperative. Climb, cruise and descent data is also published for one or more operating techniques and for all permissible altitudes and temperatures. Data comprises power settings, indicated air speed or Mach No, true air speed and fuel consumption.

See you soon

Bruno Stefano Rodriguez

Private Pilot - Flight Planning & Air Navigation Expert

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