Method for Enabling Landing on an Offset Runway

A method for determining the distance of an aircraft from an offset runway during a landing by offset approach, the offset runway being situated at a distance D from a main runway equipped with at least one elevation beacon, comprising:

• determining the height h at which the aircraft is situated, the height being determined with respect to a point T1 of the offset runway, the height being measured by a radioaltimeter with which the aircraft is equipped,
• determining the angle of elevation φ of the MLS mode by using the information of the elevation beacon provided by an elevation beacon with which said main runway is equipped,
• determining the value of the distance ρ of the aircraft from the azimuth beacon by using the following formula:
• ρ
• =
• (
• h
• Tan
• 
• (
• ϕ
• )
• -
• D
• 
• 
• 2
• Cos
• 
• (
• θ
• )
• )
• 2
• +
• h
• 2
• where θ and φ are the angles decoded by the MMR corresponding respectively to the angle between the aircraft and the azimuth beacon and the angle between the aircraft and the elevation beacon and D2 is defined as the distance between the azimuth beacon and the elevation beacon along the x axis, with x, y and z the coordinates of the aircraft in the reference frame of the elevation beacon,
• using said distance ρ to obtain a point of location of the aircraft in an offset runway reference frame.