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This rule applies to the destination airport, the destination alternate airport, or any en route alternate airport. 

J. APPENDIX 

1. APPENDIX 1 : ALTIMETRY - TEMPERATURE EFFECT 

Here’s a concrete example: Consider the case of Switzerland’s Sion airport. 

During an ILS approach on Runway 26, it is required to overfly given waypoints at given geometrical altitudes, whatever the temperature conditions (Figure J1). For example, at 21 Nm from the glide antenna, the aircraft must be at a height of 8,919 feet above the runway, or at a true altitude of 10,500 feet above mean sea level. 

The transition altitude shown on Figure J1 is 16,000 feet, corresponding to a height of 14,419 feet. 

Figure J2 provides the indicated altitude values to maintain the required true altitude for different temperature conditions: 

When temperature is ISA - 10: 

True altitude 16,000 feet 10,500 feet 

Indicated altitude 16,600 feet 10,900 feet 

 altitude 600 feet 400 feet 

When temperature is ISA - 20: 

True altitude  16,000 feet 10,500 feet 

Indicated altitude 17,300 feet 11,350 feet 

altitude 1,300 feet 850 feet 

Conclusion: 

When the temperature moves away from the standard, altimetric errorincreases. 

The altimetric error induced by temperature is proportional to altitude. 

2. APPENDIX 2 : TAKEOFF OPTIMIZATION PRINCIPLE 

This section is specifically designed to explain the takeoff optimization principle. The optimization objective is to obtain the highest possible performance-limited takeoff weight, while fulfilling all airworthiness requirements. 

For that purpose, it is necessary to determine what parameters influence takeoff performance and offer a freedom of choice. For instance, the Outside Air Temperature is a parameter which influences takeoff performance, but which cannot be chosen. This is a sustained parameter. 

The following table gives an exhaustive list of parameters which influence takeoff performance. The left column shows sustained parameters, while the right one indicates parameters for which a choice is possible (free parameters). 

Table J3: Influent Takeoff Parameters 

2.1. Takeoff Configuration 

Takeoff can be accomplished with one of the following three possible takeoff configurations: Conf 1+F, Conf 2 or Conf 3, on fly-by-wire aircraft. 

Each configuration is associated with a set of certified performance and it is, therefore, always possible to determine a Maximum TakeOff Weight (MTOW) for each takeoff configuration. As a result, the optimum configuration is the one that provides the highest MTOW. 

As a general rule, Conf 1+F gives better performance on long runways (better climb gradients), whereas Conf 3 gives better performance on short runways (shorter takeoff distances). Sometimes, other parameters, such as obstacles, can interfere. In this case, a compromise between climb and runway performance is requested, making Conf 2 the optimum configuration for takeoff. 

 

2.2. Air Conditioning 

Air conditioning, when switched on during takeoff, decreases the available power and thus degrades the takeoff performance. It is then advisable to switch it off during takeoff, but this is not always possible as some constraints exist (high air temperature in the cabin or/and company policy), unless APU bleed is used. 

2.3. Takeoff Speed Optimization 

Takeoff speeds represent the most important source of optimization and MTOW gain. The following section shows how this optimization is achieved thanks to speed ratios (V1/VR and V2/VS). 

2.3.1. Speed Ratios: V1/VR and V2/VS 

2.3.1.1. V1/VR Range 

The decision speed V1 must always be less than the rotation speed VR. But, as VR depends on weight, the maximum V1 value is not fixed, whereas the maximum V1/VR ratio is equal to one (regulatory value). 

Moreover, it has been demonstrated that a V1 speed less than 84% of VR renders the takeoff distances too long and doesn’t, therefore, present any takeoff performance advantages. Consequently, the minimum V1/VR ratio is equal to 0.84 (manufacturer value). 

This is why the V1/VR ratio is used in the optimization process, since its range is well-identified: 

0.84 ≤ V1/VR ≤1 

Any V1/VR increase (resp. decrease) should be considered to have the sameeffect on takeoff performance as a V1 increase (resp. decrease). 

2.3.1.2. V2/VS Range