Narrative:

I was working sectors 88/90 which are the non-radar oceanic sectors which primarily work traffic between the new york and boston metro areas to the eastern caribbean. I had two aircraft; aircraft Y and aircraft X which were in trail and on the same routing through my airspace into the san juan cerap's airspace. Both aircraft were assigned mach numbers as required by the ZNY SOP and mach number technique was being utilized to allow for a reduced 10 minute longitudinal separation standard. The aircraft were getting near the san juan boundary and I called san juan to coordinate both aircraft (and a few others) as required per the LOA; SOP; and faah 7110.65.I first gave the sju controller aircraft Y (front aircraft); which was crossing hancy with an estimate of xa:09; FL350; and speed M.79. I then proceeded to coordinate other aircraft and then coordinated aircraft X which was behind aircraft Y. I passed aircraft X's estimate of hancy at xa:21; FL350; and M.81. The controller told me unable and that I did not have adequate separation between the two aircraft. After being told I did not have adequate separation; knowing I did; I questioned the controller about what he meant. I was proposing two turbojet aircraft who were assigned mach numbers with 12 minutes in trail at the boundary. At hancy; sju has known radar coverage which would reduce the separation standard to 5 miles after they proceed south beyond hancy. As such; I am only required to provide a minimum of 10 miles separation between the turbojet aircraft at the exit point. The sju controller adamantly argued that I needed 14 minutes of spacing between the aircraft because the back aircraft was two mach numbers faster. I asked him what rule he was basing this on and his response was the faah 7110.65 the only mention of 14 minutes within the non-radar oceanic section is the mach number technique table in section 8-3-3 which states the time required between aircraft at their entry point into oceanic airspace based upon the speed difference and distance traveled. This table takes into account that the aircraft will have the required 10 minutes of separation at the exit point if they enter with the proper time spacing. According to this chart; if I had entered the airspace at 14 minutes of spacing; I would have 10 minutes at the boundary exiting as long as it was not more than 1200 miles (when the trailing aircraft is 2 mach numbers faster). The sju controller was adamant and made me reduce the back aircraft to M.80; and approved 12 minutes of separation.I am concerned as this is a blatant misapplication of a non-radar rule which puts extra workload on the oceanic controllers; delays aircraft by unnecessarily slowing them down; and creating confusion while on the line during coordination. We use these rules all day long and the fact that it is so misunderstood in this case is unfathomable. The issue was brought to the supervisor's attention after the incident occurred. There were no losses of separation or further incident regarding these two aircraft.provide clarification/reminder to the sju center control personnel of the proper application of mach number technique with aircraft which are faster behind entering radar airspace.

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Original NASA ASRS Text

Title: ZNY Center Controller was instructed to reduce the speed of an in-trail aircraft by an adjacent Center to comply with non-radar oceanic separation standards. The Center Controller was using appropriate separation and states the adjacent Center's instruction was unnecessary.

Narrative: I was working sectors 88/90 which are the non-radar Oceanic sectors which primarily work traffic between the New York and Boston Metro areas to the Eastern Caribbean. I had two aircraft; Aircraft Y and Aircraft X which were in trail and on the same routing through my airspace into the San Juan CERAP's airspace. Both aircraft were assigned Mach numbers as required by the ZNY SOP and Mach Number Technique was being utilized to allow for a reduced 10 minute longitudinal separation standard. The aircraft were getting near the San Juan boundary and I called San Juan to coordinate both aircraft (And a few others) as required per the LOA; SOP; and FAAH 7110.65.I first gave the SJU Controller Aircraft Y (Front Aircraft); which was crossing HANCY with an estimate of XA:09; FL350; and speed M.79. I then proceeded to coordinate other aircraft and then coordinated Aircraft X which was behind Aircraft Y. I passed Aircraft X's estimate of HANCY at XA:21; FL350; and M.81. The controller told me unable and that I did not have adequate separation between the two aircraft. After being told I did not have adequate separation; knowing I did; I questioned the controller about what he meant. I was proposing two turbojet aircraft who were assigned Mach numbers with 12 minutes in trail at the boundary. At HANCY; SJU has known radar coverage which would reduce the separation standard to 5 miles after they proceed south beyond HANCY. As such; I am only required to provide a minimum of 10 miles separation between the turbojet aircraft at the exit point. The SJU controller adamantly argued that I needed 14 minutes of spacing between the aircraft because the back aircraft was two Mach numbers faster. I asked him what rule he was basing this on and his response was the FAAH 7110.65 The only mention of 14 minutes within the non-radar oceanic section is the Mach Number Technique table in section 8-3-3 which states the time required between aircraft at their ENTRY point into oceanic airspace based upon the speed difference and distance traveled. This table takes into account that the aircraft will have the required 10 minutes of separation at the exit point if they enter with the proper time spacing. According to this chart; if I had entered the airspace at 14 minutes of spacing; I would have 10 minutes at the boundary exiting as long as it was not more than 1200 miles (when the trailing aircraft is 2 Mach numbers faster). The SJU controller was adamant and made me reduce the back aircraft to M.80; and approved 12 minutes of separation.I am concerned as this is a blatant misapplication of a non-radar rule which puts extra workload on the oceanic controllers; delays aircraft by unnecessarily slowing them down; and creating confusion while on the line during coordination. We use these rules all day long and the fact that it is so misunderstood in this case is unfathomable. The issue was brought to the supervisor's attention after the incident occurred. There were no losses of separation or further incident regarding these two aircraft.Provide clarification/reminder to the SJU Center control personnel of the proper application of Mach number technique with aircraft which are faster behind entering radar airspace.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.