Reacting to last September’s fatal collision of an Embraer Legacy and Boeing 737 over the Amazon jungle, the NTSB yesterday called for improved certification standards for traffic alert and collision avoidance systems (TCAS). The Safety Board wants pilots to receive clearer warning messages when the TCAS has stopped functioning. A report issued by Brazilian authorities said that the Legacy’s transponder stopped providing ATC returns about 55 minutes before the collision. Preliminary findings of the investigation indicate that the Legacy’s TCAS was not functioning at the time of the collision. From CVR conversations, it is clear the pilots were unaware of failures of the transponder or TCAS before the airplanes struck each other. The NTSB urged the FAA to adopt certification criteria requiring pilots to acknowledge TCAS failure messages. The Board also recommended educating pilots about the circumstances of the Brazilian accident, as well as studying whether future terrain awareness and warning systems also should adopt enhanced warnings.