Abstract: Pilots use paper-based documentation and electronic systems to guide them following the procedures to ensure safety,efficiency and comfort on commercial aircrafts.The Onboard Context-Sensitive Information System (OC-SIS)is developed to provide operational information on flight,system,performance,and navigation in normal,abnormal and emergency situations.Its content is organized using a hyperlinked three-layer information structure:need-to-know or safety-critical information (Level 1);nice-to-know (Level 2);and need-to-be-understood (Level 3).The claim is that the use of contextual information facilitates access to appropriate operational content at the right time either automatically or on demand.OCSIS is tested using human-in-the-loop (HITL)simulations that involve professional pilots in the simulator. Preliminary results are encouraging because they show that OCSIS is useful for accessing operational information and pro-viding additional features that paper-based documents do not have.