4Ascertainment of OLS and PANS‑OPS surfaces

#### 4 Ascertainment of OLS and PANS‑OPS surfaces (1) An OLS for an airport is a surface ascertained in accordance with the procedures in Annex 14 to the Chicago Convention. (2) A PANS‑OPS surface for an airport is a surface ascertained in accordance with the procedures in document number 8168 OPS—611, Procedures for Air Navigation Services, Aircraft Operations, published by the International Civil Aviation Organization on 11 November 1993. > Note: OLS has customary use as an acronym for Obstacle Limitation Surface. PANS‑OPS is an acronym for Procedures for Air Navigation Systems Operations. (3) In this regulation: > Chicago Convention has the same meaning as in the Air Navigation Act 1920.