Taxiway, Apron Entrance--A taxiway which connects a parallel taxiway and an apron.
Taxiway, End Turnoff (Entrance Taxiway) (Connecting Taxiway) (Crossover Taxiway)--A
taxiway located at the end of the runway that serves as both an access and departure location for aircraft
at the runway thresholds.
Taxiway, High-Speed Turnoff (High-Speed Exit) (Acute-angled Exit Taxiway)--A taxiway located
intermediate of the ends of the runway and "acute" to the runway centerline to enhance airport capacity
by allowing aircraft to exit the runways at a faster speed than normal turnoff taxiways allow. Aircraft
turning off runways at high speeds (maximum 100 kph [55 knots]) require sufficient length for a high-
speed turnoff taxiway to decelerate to a full stop before reaching the parallel taxiway.
Taxiway, Normal Turnoff (Ladder Taxiway) (Intermediate Taxiway) (Exit Taxiway)--A taxiway
located intermediate of the end of the runway, typically perpendicular to the runway centerline that
allows landing aircraft to exit and clear runways as soon as possible.
Taxiway, Parallel--A taxiway which parallels the runway. The curved connections to the end of the
runway permit aircraft ground movement to and from the runway and are considered part of the parallel
taxiway when there are no other taxiway exits on the runway.
Taxiway Turnoff--A taxiway leading from a runway to allow landing aircraft to exit and clear the
runway after completing their initial landing roll.
Threshold Crossing Height--The height of the straight line extension of the guide slope above the
runway at the threshold.
Tiedown Anchor--A device, installed in certain airfield pavements, to which lines tying down an
aircraft are secured. Grounding may be provided. This is not to be confused with the aircraft trim pad
and thrust anchor shown in Attachment 16.
Touchdown Point--A designated location on a landing lane, taxiway, or runway for permitting more
rapid launch or recovery of helicopters in a high density area.
Towway--A paved surface over which an aircraft is towed.
Transitional Surface-- An imaginary surface that extends outward and upward at right angles to the
runway centerline and the runway centerline extended at a slope ratio of 7H:1V. The transitional
surface connects the primary and the approach departure clearance surfaces to the inner horizontal, the
conical, and the outer horizontal surfaces.
Transitional Surfaces (Rotary-Wing)--The imaginary plane which connect the primary surface and
the approach-departure clearance surface to the horizontal surface, or extends to a prescribed horizontal
distance beyond the limits of the horizontal surface. Each surface extends outward and upward at a
specified slope measured perpendicular to the runway centerline or helipad longitudinal centerline (or
True North--The direction from an observer's position to the geographic North Pole. The north
direction of any geographic meridian.
Unsuppressed Power Check Pad--A power check pad without an enclosure or other type of noise
suppressor. It is generally used as a back up or interim facility to a suppressed power check pad. The
unsuppressed power check pad, in its simplest form, is a paved area on which full power engine
diagnostic testing can be performed without noise or jet blast limitations.