Narrative:

During the approach, the captain was watching a call develop and push across the airport. I relinquished the controls to the captain. Ord was landing on runway 14R and 22R. The line was approximately 30 mi long, 3-5 mi wide and appeared to be over the field. It printed solid magenta on the turbulence mode of our radar. The tower frequency was extremely congested. At 700 AGL, we noticed 2 lightning discharges at 11 and 1 O'clock, then encountered moderate turbulence and moderate rain. At this point, the captain made a decision to go around. The captain made his intentions known to me and instructed me to tell the tower. The congestion on the frequency was so bad all we heard from tower was 120 degree heading. That was a good heading for us because the cell was worse to the west, and the published miss called for a turn north which would have run us into the cell as well as into traffic for 14R. It took a while to confirm heading and altitude the tower wanted. Initially attempted to climb to 4000 ft as published. While in the turn we entered into one of the cells and encountered +/- 200 ft altitude excursions, with moderate to severe turbulence. While in the turn to 1200 approach control told us to tighten the turn and continue to 90 degree. While in a 30-35 degree bank at 4300 ft (we had been cleared to 5000 and on the way), we received a 'terrain' warning on the GPWS (possibly indicating a near miss). We continued around and made a normal approach and landing. The tower queried us as to the reason for the go around (was it because of 'that block cell'). We responded that we had, and tower said that 'the cell looked bad to them too.' no one else was going around. That's why we delayed until 700 ft AGL. The captain made an excellent decision to abort the approach and go around. Sometimes following the pack can lead you astray. Callback conversation with reporter revealed the following information. The captain secondary reporter took over the controls as he had a brand new first officer. The chief pilot called the tower to see if there had been any problem generated by the go around and to see if the non standard heading was for the reporting aircraft. It was, and there was no problem. The GPWS warning remains a mystery, although it may have been another aircraft. The reporter does not know if his TCASII was on and working, but it probably was. There was no TCASII warning.

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Original NASA ASRS Text

Title: AN ACR MLG FLEW A NON-STANDARD MISSED APCH IN HVY WX AT ORD.

Narrative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

Data retrieved from NASA's ASRS site as of July 2007 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.