ACCELERATE – STOP DISTANCE AVAILABLE (ASDA). The runway plus
stopway length declared available for the acceleration and deceleration of an
aircraft aborting a takeoff.

LANDING DISTANCE AVAILABLE (LDA). The runway length declared available and suitable for landing.
DISPLACED THRESHOLD. A threshold that is located at a point on the runway other than the designated beginning of the runway.
DISTANCE MEASURING EQUIPMENT (DME). Equipment (airborne and ground) used to measure, in nautical miles, the slant range distance of an aircraft from the DME navigational aid.
DNL. The 24-hour average sound level, in A-weighed decibels, obtained after the addition of ten decibels to sound levels for the periods between 10 pm and 7 am as averaged over a span of one year. It is the FAA standard metric for determining the cumulative exposure of individuals to noise.
DOWNWIND LEG. A flight path parallel to the landing runway in the direction opposite to landing. The downwind leg normally extends between the crosswind leg and the base leg. Also see Traffic Pattern.
EASEMENT. The legal right of one party to use a portion of the total rights in real estate owned by another party. This may include the right of passage over, on or below property; certain air rights above property, including view rights; and the rights to any specified form of development or activity, as well as any other legal rights in the property that may be specified in the easement document.