EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness; Workload
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Flight Crew Became Reoriented; Flight Crew Returned To Gate; Flight Crew Took Evasive Action
Company Policy; Environment - Non Weather Related; Weather; Procedure
We experienced a deice fluid failure due to heavy snow which resulted in a return to gate; delayed flight; and delayed flight the next morning. We taxied to the deice pad without delay. We requested Type I and Type IV fluid because the snow was falling. While being deiced we figured our holdover time was between 1:15 and 2:00 based on snow fall with a temperature of 1C using the Type IV Kilfrost ABC-S Plus chart. We figured the snow intensity as moderate based on the ATIS's available to us which indicated visibility of between 1 1/2 and 2 1/2 SM which put the snowfall at moderate intensity according to the QRH chart. After the first application of Type IV fluid I noticed that my Direct Vision (DV) window had snow on it and requested that the aircraft be inspected again. The deice crew must have noticed snow on the rest of the aircraft because they immediately started applying Type I and another round of Type IV. After the second application of Type IV I noticed the same thing on my DV window. The de-ice crew located a third truck to help with a third application. After the third application the aircraft seemed to be clean so we made our way to Runway 3 as quickly as we possible. While approaching the runway we did the required pre-takeoff check from the cockpit. I was having trouble seeing my wing and the First Officer said he thought there was snow on his winglet. I asked the flight attendants to check the wings from the cabin but they couldn't see much. I went to the cabin to inspect the wings for myself and discovered that every window on the left side of the aircraft was snowed over and though it was difficult to see there was snow on both wings (the left; upwind side of the aircraft had much more snow). I coordinated with Dispatch to return to the gate for fuel since we only had about 500 LBS left and we had already been off the gate for about 1:30. While researching for this report I discovered that the visibility dropped to 3/4 SM during this time period for 35 minutes. This put the snowfall intensity to heavy; for which no holdover time exists. Our final application began at about the mid time frame of that 35 minutes but we never saw an ATIS that indicated visibility as low as 3/4 SM. Had we known that it would have been clear why the deice fluid had failed. I made announcements though the whole event updating our status. I also coordinated with Dispatch via ACARS and phone when able. When we returned to the gate I made the required FAA 3 hour rule announcement. About half of the passengers decided to leave the aircraft while we refueled and some decided not to return. The second time we pushed back we were able to deice without incident. The flight was uneventful. We were late getting into our filed destination which took us below required rest so Crew Scheduling put us on reduced rest and delayed our flight in the morning. They took us off of our second flight so as far as I know; the only flights that were affected were the two that we operated.We didn't notice that the snow fall had reached the level of Heavy. It's possible that there were ATIS reports which we missed (they were updating frequently) or that the ATIS never reported visibilities of 3/4. Either way; I'm not aware of a program to stop deicing when no holdover times exist. It seems that it is entirely up to crews. I'm guessing that every carrier uses the same charts we do so it would make sense that deicing stops when holdover times don't exist. This would add a layer of safety to the system. My First Officer and I were primarily responsible for spotting the failure of the deice fluid which is concerning because of how limited our view of the aircraft is from the cockpit. It seems that the deice crew was going to let us go after the first application of fluid. Later on they told us that the snow was sticking to the aircraft nearly as quickly as they could spray it. I don't know what the safety culture is with deice crews but if they don't feelthey can speak up when they see something unsafe there may be a problem. I asked if we could position the aircraft into the wind in order to minimize the wind factor but the logistics of the deice pad wouldn't allow it. I'm being critical but in the end the procedures in place stopped an unsafe situation before it became a problem. It's a rare event that deice fluid fails. In this case; training and the resources we had available (QRH; WOP on EFB) allowed us to identify and correct the situation.
An ERJ-170 flight crew deiced four times before the aircraft remained acceptably clear of snow and he determined after the fact that during the first deice cycles heavy snow was falling for which no holdover time exists. During the final deice cycle the Deice Crew acknowledged the aircraft did not remain clean during the first three cycles; but they failed to alert the crew.