Heavy Transport
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Flight Crew Diverted; Flight Crew Executed Go Around / Missed Approach
Weather; Company Policy
At 300 feet on the ILS 8L (IAH); the windshear alert and guidance system activated and we accomplished the escape maneuver. We were then vectored for the ILS 8R and the windshear system activated again at approximately 1;200 feet. At the same time; we were maintaining visual separation from an RJ on approach to 8L. When we initiated the escape; we were not able to safely continue straight ahead due to severe weather at 12 o'clock and we also began to encounter hail and had no choice but to turn left towards the RJ traffic. I maintained visual separation during the climbing windshear escape maneuver while crossing well above the traffic. The controller insisted that we fly runway heading but we could not safely comply. We maintained safe separation from the RJ while we turned in the only direction we could go. No TCAS alerts occurred. The controller then cleared us to climb and maintain 3;000 feet; but I was unable to get the aircraft leveled off before reaching 3;900 feet and then descended back to 3;000 feet.
[Report narrative contained no additional information.]
Air cargo crew executed two go-arounds at IAH due to windshear system activation with an approaching thunderstorm and then diverted.