Interview Questions

[Flyforfood]

Hello everyone,

I am trying to prepare for an interview. I have hit the usual "gouge" websites and have been stumped on a few questions. I have looked in the AIM, the PCD, and an instrument oral exam guide. I've never been the best at playing seek and find in the AIM, so here it goes:

1. What is balanced field length?


2. How far past the end of the runway does the ALS (Approach Lighting System) extend?


Thanks in advance everyone.

 

[avbug]

Balanced field length is the runway length in which the takeoff distance is the same as the number of feet required to accelerate an airplane to a go/no-go speed, decide to abort the takeoff, and come to a complete stop. The condition of equal distances for either stopping or continuing the takeoff is called a "balanced" field length.

Balanced field length where the runway length (or runway plus clearway and/or stopway) where, for the takeoff weight, the engine-out accelerate-go distance equals the accelerate-stop distance.

Acclerate-go distance is the horizontal distance from the start of the takeoff to the point where the airplane reaches the prescribed screen height above the takeoff surface with the critical engine having failed at the designated speed.

Accelerate-stop distance is the horizontal distance from the start of the takeoff to the point where the airplane is stopped in the runway or runway and stopway, when the stop is initiated at V1 and completed using the approved procedures and specified conditions.

In conjunction with these definitions, it's well to know about critical field length. This is defined as the minimum runway length (or runway plus clearway and/or stopway) required for a specific takeoff weight. This distance may be the longer of the balanced field length, 115% of the all engine takeoff distance, or established by other limitations such as maintaining V1 to be less than or equal to VR.

The operator of a turbine-powered category airplane must determine that the runway being used, plus any available stopway or clearway, is long enough to either safely continue or reject the takeoff from a defined go/no-go point. The go/no-go point occurs while the airplane is accelerating down the runway for takeoff when the airplane reaches a speed known as V1.

The assure that the takeoff can be safely continued from the go/no-go point, the length of the runway plus any clearway must be long enough for the airplane to reach a height of 35 feet by the end of that distance, even if a total loss of power from the most critical engine occurs just before reaching the V1 speed. This distance is commonly referred to as the accelerate-go distance.

In case the pilot finds it necessary to reject the takeoff, the runway plus any stopway must be long enough for the airplane to be accelerated to the V1 speed and then brought to a complete stop. This distance is known as the accelerate-stop distance.

The choice of V1 speed affects the accelerate-go and accelerate-stop distances. A lower V1 speed, corresponding to an engine failure early in the takeoff roll, increases the accelerate-go distance and decreases the accelerate-stop distance. Conversely, a higher V1 speed decreases the accelerate-go distance and increases the accelerate-stop distance. When V1 is selected such that the accelerate-stop distance is equal to the accelerate-go distance, this distance is known as the balanced field length. In general, the balanced field length represents the minimum runway length that can be used for takeoff.

The V1 speed selected for any takeoff depends on several variables, including the airplane's takeoff weight and configuration (flap setting), the runway length, the air temperature, and the runway surface elevation (airport altitude). The takeoff performance and limitation charts in the Airplane Flight Manual (AFM) are developed in accordance with the FAA airworthiness standards in subpart B of the Federal Aviation Regulations (FAR), part 25--"Airworthiness Standards: Transport Category Airplanes," using data gathered during comprehensive flight tests completed as a part of the FAA's approval of the airplane's type design.

An easy way of considering balanced field length is to think of it as the distance in which an engine failure may occur at V1, and the takeoff either continued or aborted. V1 is selected such that the distance to abort and stop equals the distance to continue and climb to 50'.

For certain airplanes, The 115% (unbalanced field length) all-engines takeoff distance is usually the controlling distance. A V1 selected to achieve a balanced field length usually exceeds VR, a condition which is not allowed by the regulations. For these airplanes, V1 is normally selected as identical to VR and the balanced field length concept is not applicable.

Approach Lighting Systems extend 2400 - 3000 feet from the runway threshold for precision instrument runways and 1400 - 1500 feet for nonprecision instrument runways.