The U.S. Aviation Safety Team (USAST) explores safety topics with the potential for systemic impact. A culture of continuous curiosity and exploration of National Airspace System (NAS)-wide safety concerns is fundamental to maintaining the gold standard of aviation safety in the United States. The topics presented on this page are intended to provide safety awareness and offer a preliminary understanding of key safety issues.

The most recent safety topics are listed at the top.

Deferred TCAS (Published: December 2025 - Most Recent)

This document explains the operational implications of flying with deferred TCAS or TA-only mode, including loss of RA capability, increased pilot workload, greater reliance on ATC, and reduced traffic awareness. It also outlines recommended practices such as vigilant traffic scanning, use of all available tools, and clear ATC communication to maintain safety until full TCAS service is restored.

New Airport Terminal and Runway — Lima, Peru (SPJC) (Published: July 2025)

Key operational safety considerations following the opening of a new terminal and parallel runway (16R/34L) at Jorge Chávez International Airport (SPJC) in Lima, Peru. Developed in collaboration with the Peruvian Collaborative Aviation Safety Team (P-CAST) and the U.S. Commercial Aviation Safety Team (USCAST), this information sheet identifies emerging hazards such as approach and landing misalignments (ALM), taxiway flow changes, and unpublished hotspots that may increase the risk of runway incursions—especially given the transition from a single-runway to a dual-runway environment. Operators flying into SPJC are encouraged to review these insights and consider them in flightcrew briefings and operational risk assessments.

ILS Autopilot Coupled Approaches – Not Authorized / Not Authorized Below Altitude (Published: July 2025)

Autopilot coupled approaches may contain restrictions due to an excessive rate of change or reversals in the slope of the glidepath. For ILS approaches that contain these restrictions, observations from ASIAS show that some flights keep the autopilot system engaged below the authorized altitude or engaged during a large portion of the final approach where autopilot is not authorized.

Line Up and Wait Overview (Published: July 2025)

Consequences of extended time in Line Up and Wait (LUAW) during mixed use operations include go-arounds, tight spacing or simultaneous occupancy, and late S-turns. A preliminary examination of LUAW and takeoff clearance instructions from ASIAS show a general increase in these undesirable events as the time between LUAW and start of roll increases.

Low Altitude Safety Events (Published: July 2025)

Observations from ASIAS indicate an increased number of reports of low altitude alerts, altitude deviations on approach, and Ground Proximity Warning System (GPWS) events across the NAS from pilots and controllers. The USAST requested more information on the potential causes and risks associated with these types of events.