When rolling the aircraft the up-going wing will experience more drag than the down-going wing. This will result in a yawing moment that directly opposes the desired direction of turn. (i.e.: rolling left will cause a right yaw.)

An ILS (Instrument Landing System) is defined as a precision runway approach aid based on two radio beams which together provide pilots with both vertical and horizontal guidance during an approach to land.

The ILS aerials transmit two lobes. For a pilot on final, the lobe to his right is modulated at a frequency of 150 Hz and the one to his left at 90 Hz. The point where the lobes meet is the centre line of the runway. As the signals on the lobe move from the centre line to either side, their amplitude increases. This means the magnitude of their depth modulation increases. The depth modulation can be considered as a percentage. For example, if an aircraft receives a 15% depth modulated signal from the left and a 5% depth modulated signal from the right, the difference of modulation becomes 10% to the left. This electrical imbalance is sent to the aircraft and the localizer needle is designed in such a way that it will show a deflection to the opposite direction, telling the pilot to go to the right.

When on the centre line, the modulation difference is zero and the needle centres itself.

The glide slope or the glide path provides the pilot with vertical guidance. The glide slope is set such that a glide slope angle of 3 degrees is maintained by the pilot. The needle of the slope moves up, if the aircraft is too low and moves down if it is too much above the required path. The glide slope is on the UHF band (329.15 - 335 Mhz).

The glide slope operates the same way as the localizer. The only difference is that the lobes are emitted on the vertical plane. The upper lobe is modulated at 90 Hz while the bottom one at 150 Hz. Exactly the same way as before, the needle of the slope moves based on the difference in depth modulation. As like before when the modulation difference is nil, the glide needle moves to the very centre of the instrument.

TORA= Takeoff Run Available, the length of runway declared available and suitable for the ground run of an aeroplane taking off.

TODA= Takeoff Distance Available, the length of the take off run available (TORA) plus the length of the clearway, if available.

ASDA= Accelerated Stop Distance Available, the length of the takeoff run plus the length of the stopway, if available.

A clearway is an area beyond the paved runway, free of obstructions and under the control of the airport authorities. The length of the clearway may be included in the length of the takeoff distance available (Take Off Distance Available (TODA)). For example, if a paved runway is 2000 m long and there are 400 m of clearway beyond the end of the runway, the takeoff distance available is 2400 m long.

The stopway is an area beyond the runway which can be used for deceleration in the event of a rejected takeoff.

Screen height: TODR is the distance from the brake release point to the point where the aircraft gains a height of 35 ft above the ground. This 35 ft is what we call the screen height. While 35 ft is the screen height for class A airplanes, it is 50 ft for class B airplanes.

On a wet runway, the screen height is reduced to 15 ft.

Windshear is a change of wind speed and/or direction from place to place, including updraughts and down draughts.

It is ussualy characterized by a strong change over a short distance. Windshear can effect the flight path and airspeed and can be hazardous.

Altimeter errors:

Instrument error Pressure error Time-lag error Barometric error

Angle of attack is the angle between the chord of the aerofoil and the relative airflow.

Angle of incidence is the angle between the chord and the aircrafts longitudinal datum.

V1 is lower when the runway is wet than when the runway is dry, because of the longer ASDR on a wet runway.

Decision altitude (precision), the altitude at which a decision must be made during an ILS, MLS, or PAR instrument approach to either continue the approach or to execute a missed approach.

To increase the strength of the surfaces.

The same strategy is employed by plastic water bottles, by adding ridges to a surface you increase it's structural rigidity

Precision Approach Path Indicator