Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 208; Flight Crew Type 4582
Situational Awareness; Troubleshooting; Distraction; Confusion
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Weather / Turbulence
General None Reported / Taken
Human Factors; Procedure
This does not refer to our aircraft; but the departing aircraft we witnessed being deiced. We arrived in ZZZ and had to hold off the gate while the departing aircraft got deiced with a 'two-step' process. This was during the difficult weather conditions of the winter storm this past week. ZZZ apparently has one truck to deice. I can't be sure; but I think it may even have been driven by the Boom Operator rather than in the cab. So a one man/ one truck operator.As I watched him deice the aircraft I was concerned that he was not deicing correctly and would like guidance.  The way I have always understood the process to work was Type 1 the complete aircraft to deice and Type 4; then to provide the anti-ice for the specified holdover time. The whole Ramp operation appears to be contract rather than (Company) Personnel.The Iceman started at the nose and moved to the left wing with Type 1.  He then switched to Type 4 and applied that. He then moved to the tail and did the same. Type 1 followed by Type 4; he then moved to the right wing with Type 1 and Type 4. The process took quite a while even like that. My concern would be contamination of the Type 4 with Type 1 and subsequent reduction or nullification of the anti-ice ability of the Type 4 and any holdover time.If I am right and the process was incorrectly done; then it's a Safety issue that needs resolved and correct (Company) deicing procedures should be taught. If I am not; then I would like to know for my own edification.
Air carrier First Officer reported witnessing what they determined to be an inappropriate deicing procedure.