Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain BAE Systems (Operations) Limited Model BAe 146 series airplanes. This proposal would require modification of the flight annunciator box. This action is necessary to prevent traffic collision avoidance system (TCAS) aural messages and resolution advisories of the TCAS from being inhibited following a ground proximity warning system alert or test message, which could prevent the TCAS from providing attention-getting alerts, and could result in the consequent possibility of a mid-air collision or near mid-air collision. This action is intended to address the identified unsafe condition.