Date: 201205
Local time of day: 1201-1800
Location: ACK.Airport, MA
Flight conditions: VMC
Light: Daylight
Aircraft: Gulfstream IV / G350 / G450
Operating under: Part 91
Flight phase: Parked
Reporter organization: Fractional
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown
Anomaly: Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Other / Unknown
Detector: Person Flight Crew
When detected: Routine Inspection
Result: General None Reported / Taken
Contributing factors: Procedure; Airport; Human Factors
Primary problem: Ambiguous

Narrative: The following observation is 'an accident waiting to happen' at ACK (Nantucket; MA): We were parked on the back row; first spot southwest of the new fire house; facing the runway. There was another parked aircraft facing us. The gap between us proved to be tight. After getting our passenger settled; I entered the cockpit just as an inbound jet was taxiing from our left-to-right at approximately 5 KTS; going through the narrow gap described above. There was a marshaller well in front of this taxiing jet giving it a 'thumbs up'; however; the right wing was dangerously close to our nose. I expedited my exit from our aircraft; just as the taxiing jet's right wing was passing our nose--close enough that its; eye-level (for me); wing was slightly underlapping our nose. I reached out and touched both its wing and an area below our nose without a stretch. I estimate the tip of the wing was two feet below the tip of our nose and two and one half to three feet from a striking point under our nose. After the taxiing jet was away from our aircraft and near its parking location; I jogged over to the marshaller and professionally--but very sternly--told him to never marshal a plane that close to 'my aircraft' again. He said he would like to discuss this with me; once he had the other aircraft chocked. I went back to our plane to continue my duties. When the marshaller came near our aircraft; I exited and reiterated how very close he had come to causing damage to two multi-million dollar aircraft. He apologized; but added that they were very busy and needed to 'keep the planes moving.' I doubt my words had any effect. The above situation will likely go on until a wing smashes into another aircraft--or; perhaps; until someone with influence can impress upon the airport management that this type of activity is not in his/her best interest. Troubling; too; is that I know (for a fact) that the other aircraft in this scenario has very conservative procedures--much like ours--that; if followed; would not have allowed this situation to have gone this far. I do not know who should voice our concern; but it takes little imagination to picture how easily this situation could have 1) cost our company an unhappy customer; 2) cost us downtime of a valuable resource; 3) impacted another aircraft in the same way; 4) tarnished the reputation of the well-meaning line folks at ACK; and 5) likely resulted in the loss of a job for at least one person--and a too-late re-evaluation of the taxiing procedures at ACK. Finally; of all the times when there should be extra vigilance; it is when the tempo of ops is great--such as this holiday weekend--rather than a decrease in standards.




Synopsis: A GIV Captain reported aircraft being taxied in very tight confines under a Marshall's control at ACK; suggesting that two to three feet of clearance is not sufficient.