ASRS CALLBACK includes excerpts from ASRS incident reports with supporting commentary. In addition, CALLBACK may contain summaries of ASRS research studies and related aviation safety information. CALLBACK is one of the ASRS's most effective tools for improving the quality of human performance in the National Aviation System (NAS) at the grass roots level.

Tuesday, April 28, 2009

CALLBACK Issue 352

From NASA's Aviation Safety Reporting System

Issue 352

April 2009


Problems with PDC Formats

In 1990, the Pre-Departure Clearance (PDC) program was introduced at a number of U.S. airports. This system allows pilots to obtain IFR clearances through aircraft ACARS (Aircraft Communication Addressing and Reporting System) display units prior to taxi. The program has dramatically reduced voice communications and related frequency congestion on Clearance Delivery frequencies at participating airports.

ASRS performed analyses of PDC related incidents in 1993 (Directline Issue #5) and 1996 (Operational Issues Bulletin), and found that confusing PDF formats were one of the leading problems reported. Both the Directline article and the Operational Issues Bulletin are available on the ASRS web site (, under "Safety Publications."

Another increase this past year in PDC-related reporting prompted ASRS to revisit PDC issues. A recent review of 71 relevant incident reports confirmed that a concern we first identified 16 years ago—PDC formats—is still a problem for many pilots. Specifically, our recent review identified the following PDC format issues:

• Listing of both filed and cleared routes

• Unclear routing formats

• Unnecessary route revisions (amendments).


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