Just to add to Buff's post, the discipline involved in the HR department is referred to as Human Resource Management, or HRM (also sometimes referred to as Strategic Human Resource Management - or SHRM).
The progression from "Personnel Management" to "HRM" was more than just a 90's name change however.
The progression from PM to HRM is described as an evolutionary rather than revolutionary one. The main difference between the two are the former refers to a set of functions or activities, where the latter "assumes all personnel activities are integrated with each other, and strategically with the organisational objectives," (Nankervis et al, 1996).
A typical HR department within an airline would not only look after what are traditional PM functions (salaries, sick leave, etc..), but also be actively involved in the selection of the "human resource" itself, providing an effective induction and review program, training, employee welfare and career counceling (to name a few).
As you could imagine, selection and training within an airline is paramount to the success of that airline. This is due to both the background work required to maintain safety standards, and the amount of people you have with direct contact to the public.
P.S. Looking at a move to Airline Industrial Relations Legalman?