The operational/functional requirements for the new Microwave Landing System (MLS) are examined for STOL operations. The study utilizes a nonlinear six-degree-of-freedom simulation of a De Havilland Buffalo C-8A aircraft and automatic flight control system to assess the MLS/STOL accuracy, coverage, and data rate requirements for the azimuth, DME, primary elevation, and flare elevation functions. The aircraft performance is statistically determined for representative curved flight paths through touchdown. A range of MLS errors and coverages, environmental disturbances, and navigation filtering are investigated. The study indicates that STOL applications do not place any unique requirements on the MLS.

Microwave Landing System Requirements for STOL Operations

Nonlinear trajectory following in the terminal area - Guidance, control and flight mechanics concepts using the microwave landing system

The results of an investigation made to assess the Microwave Landing System (MLS) Requirements for use by civil STOL aircraft are described. The principal MLS characteristics investigated in the report were signal accuracy and volume of coverage. The study utilized a nonlinear six-degree-of-freedom digital simulation of a De Havilland Buffalo C-8A aircraft. Fully automatic control of timed curve flight down to touchdown was simulated. Selected MLS accuracy and coverage parameters for the azimuth, primary elevation, flare evelation and DME signals were varied. The resulting STOL aircraft system performance in following a representative curved flight path was statistically determined. Coverage requirements for STOL aircraft operating in the terminal area environment were also investigated.

https://ntrs.nasa.gov/api/citations/19740003318/downloads/19740003318.pdf

Preliminary assessment of the microwave landing system requirements for STOL operations

The results of analysis directed towards determining Microwave Landing System (MLS) signal requirements for conventional aircraft are discussed. The phases of flight considered include straight-in final approach, flareout, and rollout. A limited number of detailed problems in performance analysis are studied. Data from computer simulation, covariance propagation and system optimization, with a careful selection of variables provides a means for generalizing from the results of specific experiments to more comprehensive functional, data rate, beam noise, and I control system requirements for automatic landing in turbulence. Conclusions point toward the requirements for a re-evaluation of the MLS as sole primary landing aid; the problem arises during flareout in turbulence, when elevation information is inadequate to maintain precise sink rate control. Minimum suitable data rate and maximum allowable noise for final approach are also recommended.

Maurice H. Lanman

Papers

Microwave Landing System signal requirements for conventional aircraft