Date: 201602
Local time of day: 1801-2400
Location: MDT.Airport, PA
Flight conditions: IMC
Weather elements / visibility: Snow
Light: Night
Aircraft: Medium Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Human Factors; Weather; Procedure
Primary problem: Ambiguous

Narrative: We requested deice and anti-ice fluid treatment after pushback before our departure. Station personnel sprayed the aircraft with Type 1 and Type 4 fluids. The aircraft configuration and method used for deicing was the one step method; with the aircraft engine shutdown on the side receiving deice/anti-ice and the other engine operated. The APU remained off the entire time. Station advised that the Type 4 fluid being used was Clariant Max Flight 04. Consulting the HOT (Holdover Time) charts in the aircraft; the minimum holdover time using the Clariant fluid under the weather conditions should be 1:03. After being sprayed and commencing taxi to the runway; ATC advised us of a ground stop to our destination; so we returned to the gate. While sitting at the gate for some time; the First Officer and I both noticed snow accumulating on top of both wings after only approximately 45 minutes since the commencement of the application of the Type 4 fluid. We pointed out the snow accumulation to the station personnel and wanted to make sure that they understood that the Type 4 fluid was not holding up to the minimum Holdover Time. After our release by ATC; we had the aircraft deiced and anti-iced again in the same manner and departed without delay to our destination. I don't know why the Type 4 fluid underperformed its HOT. The First Officer and I both reviewed the HOT tables for the Clariant fluid; making sure that we were looking at the proper table and reading it correctly. We also double checked the current weather on the ATIS and along with the snow intensity reported on the ATIS; we also used the charts provided with the HOT tables to independently determine the snow intensity. In both instances the intensity was determined as LIGHT. The surface wind was reported as 5 knots and we were never subjected to any jet or prop blast that would have reduced the effectiveness of the fluid. In my opinion there are several possibilities why the fluid became ineffective sooner than it was supposed to.1 The fluid was somehow contaminated or diluted2 The fluid applied was not Type 43 This fluid is not appropriate for the way we configure our aircraft for deice/anti-ice4 The fluid is not a suitable Type 4 fluid as it is manufactured.5 The fluid was not actually applied at 100% as stated by the station.Make sure the anti-ice fluid is tested for quality [and] that it is applied properly and is designed to be applied with the appropriate aircraft configuration.




Synopsis: Air carrier Captain reported his aircraft was treated with Type 1 and Type 4 de-ice/anti-ice fluids; but they failed to perform as expected with regard to published holdover times.