B747-400
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Flight Crew Overcame Equipment Problem
Procedure; Human Factors; Weather
After following all extensive local and all company supplemental procedures for remote pad de-icing with the engines shut down; the aircraft was successfully de-iced and returned to take off configuration with engines running using company supplemental and normal procedures without any issues. On intercom; the ground crew was dismissed and they acknowledged by telling the crew to look for hand signals on the left side of the aircraft. Ground crew was observed moving to their vehicles on the left side and waved off with a flash of the taxi light to indicate we see them safely away for our taxi departure. After receiving clearance to taxi for takeoff on RWY XXL; FO (First Officer) began to apply breakaway power to gently taxi the heavy aircraft forward so as not to affect the aircraft behind. Our crew applied as much power as was prudent; but then heard screaming on the interphone (mostly unintelligible) and the only word we could understand was 'chocks'. Fearing injury to ground personnel or worse; taxi operations were immediately terminated and power immediately reduced to idle. Ground crew relayed chocks were still installed and to hold position. Crew complied with instructions and chocks were removed. It is unclear when/how this person was on interphone after the ground crew was dismissed and wave off given; but one of them either never left with the rest of the ground crew or came back from a safe position to the intercom perhaps noticing chocks were still installed. No ground crew personnel; vehicles or aircraft were harmed or damaged; but a language/cultural barrier was definitely at play here and could have resulted in tragedy. This is a taxi in/out remote pad de-ice operation and no marshaller was used for us to leave where a possible hold position signal could have been given instead of ground personnel risking injury to themselves by returning to the aircraft after being dismissed.
We went to deice pad at ZZZZ. All 4 engines were shut down and the aircraft was deiced and anti-iced. All 4 engines were re-started and all checklists were completed. Captain cleared the ground person off the intercom and verified the ground personnel departed on the left side of the aircraft. In addition; he saw the waveoff. After receiving taxi clearance; I attempted to taxi the aircraft. I only advanced the thrust levers a small amount because I knew there was another aircraft waiting behind us. Our aircraft did not move so I used a little more thrust and still the aircraft did not move. Two more times I advanced the thrust levers and the aircraft still did not move. Power got up to about an N1 of 37%. At that point; someone on the ground reconnected to the flight intercom and was screaming something unintelligible. I immediately reduced thrust to idle. It took a couple of seconds before I was able to understand the word CHOCK. I believe the crew that deiced us did not remove a chock and that is why we were unable to taxi. I also believe the chock was accidentally left in place and they did not realize it until they saw we could not move; even though the engines were producing enough thrust. The chock was then removed and we were able to taxi normally. Suggestions: Ground should verify all chocks removed more carefully before clearing off intercom.
B747 flight crew reported a communication breakdown between flight crew and deicing ground crew resulted in an unsafe situation.