• This site moved from forums.flightinfo.com to flightinfo.com. Please update your bookmarks.

300 Rvr T/o


Well-known member
Dec 14, 2001
Total Time

The full requirements for approved equipment for reduced visibility takeoffs are recorded in Advisory Circular AC 120-28D. While a HUD may be part of an approved package, the approval pertains to guidance capability, rather than the display. A variety of different mediums may be used to display the required information, and a HUD may be among them.

Among the requirements for approval is the requirement to track and maintain the runway centerline during a takeoff from brake release on the runway to liftoff and climb to 35 ft. AGL, and from brake release through deceleration to a stop for a rejected takeoff. The use of the takeoff system must not require exceptional skill, workload or pilot compensation. The takeoff system must provide an appropriate transition from lateral takeoff guidance (i.e., at about 35 ft. AGL) through transition to en route climb for a takeoff, and from brake release through deceleration to a stop for a rejected takeoff.

AC-120-28D Appendix 2 spells out the requirements for approval up to 35' AGL, and Appendix 9 spells out the requirements above 35 AGL. The transition mentioned above refers to the transition between the ground portion (up to 35'), and the airborne climb portion.

The intended lateral path may be established in a number of ways. For systems addressed by this appendix, the required lateral path may be established by a navigation aid (e.g., ILS, MLS). Other methods may be acceptable if shown to be feasible by a Proof of Concept (PoC) demonstration. Methods requiring PoC include, but are not limited to:

• the use of ground surveyed waypoints, either stored in an on-board data base or provided by data link to the airplane, with path definition by the airborne system,

• the use of inertial information following initial alignment,

• sensing of the runway surface, lighting and/or markings with a vision enhancement system (Indications of the airplane position with respect to the intended lateral path can be provided to the pilot in a number of ways.),

• deviation displays with reference to navigation source (e.g., ILS receiver, MLS receiver),

• on-board navigation system computations with corresponding displays of position and reference path, or by a vision enhancement system.

In addition to indications of the airplane position, the takeoff system should also compute and display command information (i.e., flight director), as lateral guidance, to the pilot, accounting for a number of parameters including airplane position, deviation from the reference path, and deviation rate. Takeoff system designs which provide only situational information, in lieu of command information, might be found acceptable, but would require a Proof of Concept demonstration. [PoC]

For certificate holders, additional approval is required by OpSpecs.