A. In order to efficiently construct, manage, and operate an airport, the defendant is a juristic person established pursuant to the Korea Airports Corporation Act, and the plaintiffs were employed by the defendant to conduct air communication business, etc., and the plaintiffs set up against 273 A, 329 B, 357C, and 579 DD (hereinafter collectively referred to as "Plaintiff A, etc.") set aside on each date indicated in the "date of retirement" in attached Table 4, respectively. The remaining plaintiffs are workers who work for the defendant until the date of closing argument of this case.

B. Under a collective agreement, the Defendant paid wages to its employees under the name of basic monthly pay, position pay, statutory appointment allowance, job grade treatment allowance, performance evaluation performance rating, self-evaluation performance rating, performance performance rating, etc. (2) The Defendant established and operated a defined benefit type (DB, Defined Benefit) retirement plan and a defined contribution type (DC and Defined Confined Befit) retirement pension plan in accordance with the Guarantee of Workers' Retirement Benefits Act.

3) Meanwhile, the Defendant calculated the ordinary wage including only the basic monthly salary, position salary, statutory appointment allowance, and job grade treatment allowance among the wages, and paid annual leave allowance based thereon to its employees. Of its employees, 1/12 of the annual average wage calculated based on each of the above allowances has been paid to its employees as a final and conclusive retirement pension trustee. (c) A collective agreement entered into between the Defendant and the labor union (hereinafter “instant collective agreement”). The Defendant’s in-house regulations and other labor union concluded between the Defendant and the retirement pension trustee.

) 및 피고의 사내규정 중 이 사건과 관련된 부분은 아래와 같다. ▣ 직원연봉규정(2014. 12. 29. 개정되기 전의 것) 제4조(용어의 정의 이 규정에서 사용하는 용어의 정의는 다음과 같다.

4. Piece rates shall be paid differently by reflecting the results of management performance evaluation in the preceding year;