Oct. 2, 2015

Denver Center has experienced numerous incidents in the last 13 months in which aircraft have incorrectly flown the YOKES4 RNAV SID, DEHLI transition by making an unexpected turn after YOKES and going direct to DEHLI or some other point in their flight plan instead of correctly following the procedure to CHICI and then DEHLI.

This is potentially dangerous because turning unexpectedly after YOKES direct DEHLI or ONL (eliminating CHICI) may put the aircraft in a head-on conflict with the arrival stream aircraft landing in the Denver terminal area. Denver has seen this happen with many different types of aircraft.

In order to resolve this issue, the YOKES departure procedure (DP) will be updated to delete the DEHLI fix and end the DP at CHICI. The YOKES4.DEHLI DP is scheduled to be changed to YOKES5.CHICI on Feb. 4. Denver Center believes this will correct the problem.

As a short-term mitigation until the YOKES DP is amended, on Oct. 15, Denver Center will implement a new Adapted Departure Route (ADR). Aircraft filed on the YOKES4, DEHLI transition will be assigned DEN.YOKES4.YOKES..CHICI..DEHLI, then the filed flight-plan route.

This ADR should be assigned prior to crews receiving their pre-departure clearance (PDC); however, in order to reduce the impact of this change on Denver International Airport’s (DEN) tower controllers, Denver Center is asking that all aircraft file: DEN.YOKES4.YOKES..CHICI..DEHLI in lieu of the DEHLI transition starting on Oct. 15 until the YOKES DP is amended in February.

NBAA emphasizes the need for pilots to understand the format of their PDC, especially with respect to the identification of an assigned SID/STAR and associated transition. It appears that these errors are occurring because pilots misinterpreted the PDC and missed the fact that a transition was assigned after YOKES. The fact that the Jeppesen chart displays the transitions separately from the SID common route ending at YOKES may have contributed to the misinterpretation and reinforced the pilot’s belief that the SID ended at YOKES and that they were cleared direct after passing that waypoint.