Effective English communication is vital for airline reservation and ticketing staff, who serve as the primary interface for international passengers. Grounded in an English for Specific Purposes (ESP) framework, this quantitative needs analysis investigates communication challenges among 73 Thai reservation personnel using a structured five-point Likert scale questionnaire. The study evaluates real-world tasks, including customer interactions, documentation, and policy interpretation. Descriptive statistics revealed moderate levels of difficulty across three domains: overall communication, linguistic proficiency, and professional English use in documentation and policy contexts. Participants with less than six years of experience reported higher overall challenges (M=3.69, SD=0.43) than those with six or more years of experience (M=3.48, SD=0.53). An independent samples t-test indicated that more experienced staff reported significantly lower challenges, specifically in professional English for documentation and policy, t(71)=2.47, p<0.05, with a moderate effect size (η²=0.08). However, no significant differences were found in overall and linguistic challenges, suggesting these difficulties persist regardless of experience level. The findings highlight a discrepancy between workplace demands and perceived competence, particularly in tasks requiring high precision. This underscores the necessity for targeted ESP training that integrates authentic aviation scenarios, industry-specific terminology,
and exposure to diverse international accents. Such insights are crucial for developing contextually relevant curricula to improve service quality, operational efficiency, and continuous professional development in the aviation industry.