Narrative:

We were in full compliance of both company procedures and the alert for ENDEE3 22L RNAV Y. We had selected; verified; executed; and briefed miing transition since it was closest and afforded less time to reprogram and re-brief. We had discontinuity as discussed after wadll. Approaching miing; we agreed it looks like we should re- select stere [RNAV Y] transition since we would not be getting miing [RNAV X]. Pm re-selected 22L RNAV Y and then stere transition. We both verified it on legs page. We agreed and executed it; with it showing miing as active waypoint; next was wadll; then the discontinuity followed by stere. At this point; we were crossing miing and got an LNAV disconnect. Within two seconds; recognized and put wadll up top and executed to go direct thus correcting the discontinuity caused lateral deviation. ATC informed us in the turn we turned the wrong way and issued a heading which we complied with (same as direct wadll which we were doing). We followed all guidance issued and were fully aware of the recent issues pilots are having with this arrival. I see two separate issues with the same arrival. One is masking the other. Fortunately there is a very simple corrective action needed to rectify the latter.ATC needs to issue a transition to the RNAV Y 22L. Leaving pilots guessing; especially in IMC conditions; on which to set up and brief is unacceptable. There simply is not enough time after crossing mingg at 4000 feet in congested airspace to rebuild and re-brief an approach.

Related reports:

Google
 

Original NASA ASRS Text

Title: B737-700 Captain describes FMC anomalies that occur when changing from the RNAV X RWY 22L to the RNAV Y RWY 22L approaching MIING on the ENDEE3 arrival to MDW. This change results in the entire ENDEE3 arrival being entered into the FMC and creates a route discontinuity after MIING.

Narrative: We were in full compliance of both Company procedures and the alert for ENDEE3 22L RNAV Y. We had selected; verified; executed; and briefed MIING transition since it was closest and afforded less time to reprogram and re-brief. We had discontinuity as discussed after WADLL. Approaching MIING; we agreed it looks like we should re- select STERE [RNAV Y] transition since we would not be getting MIING [RNAV X]. PM re-selected 22L RNAV Y and then STERE transition. We both verified it on LEGS page. We agreed and executed it; with it showing MIING as active waypoint; next was WADLL; then the discontinuity followed by STERE. At this point; we were crossing MIING and got an LNAV disconnect. Within two seconds; recognized and put WADLL up top and executed to go direct thus correcting the discontinuity caused lateral deviation. ATC informed us in the turn we turned the wrong way and issued a heading which we complied with (same as direct WADLL which we were doing). We followed all guidance issued and were fully aware of the recent issues Pilots are having with this arrival. I see two separate issues with the same arrival. One is masking the other. Fortunately there is a very simple corrective action needed to rectify the latter.ATC needs to issue a transition to the RNAV Y 22L. Leaving Pilots guessing; especially in IMC conditions; on which to set up and brief is unacceptable. There simply is not enough time after crossing MINGG at 4000 feet in congested airspace to rebuild and re-brief an approach.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.