B737 flight crew reported windshield de-ice system failure resulted in a divert to avoid weather.
Synopsis
B737 flight crew reported windshield de-ice system failure resulted in a divert to avoid weather.
Narrative
Aircraft X ZZZZ-ZZZ diverted to ZZZ1 for four windshield overheat lights on the overhead panel. I was acting as CA and flying with an LCP (Line Check Pilot); who was performing FO duties; to do my airport qualification at ZZZZ. We arrived at the aircraft and conducted all of the preflight procedures and briefings IAW (In Accordance With) appropriate SOPs. I checked the circuit breakers and did not note any open circuit breakers. My FO performed their preflight procedures and did not note any abnormalities. We proceeded through our pushback; engine start and taxi procedures normally. During the preflight checklist; we both verified the windshield heat was on. During the after start and before takeoff checklist we checked the recall and neither master caution nor the 'Anti-Ice' light illuminated during either recall check. After departing Runway XXL from ZZZZ we started to accelerate and clean up the aircraft. We performed a bleeds off takeoff and while the FO was transferring the bleeds; he noticed that the four window heat switches had the overheat light illuminated. At no point in time did we get a master caution or the 'Anti-Ice' light illumination on the dash. The FO; performing PM duties ran the checklist from the flight manual which eventually led to us leaving the window heat switches in the off position. We called Dispatch and Maintenance Control to discuss the implications of this abnormality. It was during our conversation with Maintenance Control that they directed us to look at the circuit breakers and all four window heat circuit breakers were open. Maintenance Control did not recommend we reset the breakers in flight; so we were left with four inoperative window heat switches. There was forecast icing in ZZZ so the decision was initially made to divert to ZZZ2. However; due to the fuel load we continued on to ZZZ1; so we wouldn't land overweight.We used the diversion planning guide to help us during our diversion. The diversion and diversion recovery went smoothly. When we arrived at ZZZ1 we went to Gate XX and maintenance personnel met the aircraft and were able to resolve the problem. We departed ZZZ1 for ZZZ after approximately one hour on the ground.
Second reporter narrative
On Aircraft X (ZZZZ-ZZZ); we diverted to ZZZ1 for four windshield overheat lights on the overhead panel. WX was day VMC; unrestricted vis.Filling the FO role as an LCP (Line Check Pilot) and giving the CA a ZZZZ checkout; I was the PM for this leg. We arrived at the aircraft and conducted all of the preflight procedures and briefings IAW (In Accordance With) SOP. I did the walk around and the CA performed the initial flight deck security checks and flows. During my normal FO flows; I did not notice any abnormalities. Preflight was standard and during the preflight checklist; we both verified the windshield heat was on (no OVERHEAT lights). Pushback; engine start and taxi were normal. We planned and briefed a Bleeds Off T/O (Takeoff). During the after start and before takeoff checklist we checked the recall and neither master caution nor the 'Anti-Ice' light illuminated during either recall check. We departed Runway XXL from ZZZZ; and on climbout started to accelerate and clean up the aircraft. While transferring the bleeds; I noticed that the four window heat switches had the indicator overheat lights illuminated. At no point in time did we get a master caution or the 'Anti-Ice' light illumination on the dash. I ran the checklist from the FM (Flight Manual) which eventually led to us leaving the window heat switches in the off position.Using SATCOM; we called Dispatch (who conferenced in Maintenance Control) to discuss the implications of the non-normal. Maintenance Control directed us to look at the circuit breakers where we found all four window heat circuit breakers were open. Maintenance Control did not recommend we reset the breakers in flight; so we were left with four inoperative window heat switches. Upon review of the FM and MEL; we discussed with Maintenance Control and Dispatch the conditional note to avoid operations in icing. Dispatch confirmed that we would encounter icing during our descent into ZZZ so the decision was made to divert to ZZZ1 (for landing weight considerations).IAW FM/FOM SOPs (diversion and diversion planning guide) we notified ZZZ Center and coordinated a divert to ZZZ1. The diversion and subsequent diversion recovery went smoothly. At ZZZ1; we coordinated with Operations for a gate where Operations; customs; and MX (Maintenance) met the aircraft. Only MX boarded the aircraft and after a short diagnosis; replaced the Windshield Heat panel (box). This resolved the problem. After an hour on the ground; we departed ZZZ1 for ZZZ; rest of trip was uneventful.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.