Date: 201502
Local time of day: 0001-0600
Location: BOS.Airport, MA
Light: Night
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Dispatcher
Reporter qualification: Dispatch Dispatcher
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Dispatch
When detected: Other Over several days
Result: General None Reported / Taken
Contributing factors: Airport; Human Factors; Weather; Procedure
Primary problem: Ambiguous

Narrative: Two NOTAMs for BOS are confusing.  NOTAM numbers AZZZZ/ZZ and AYYYY/YY restrict Cat D aircraft from conducting S-ILS 33L and 4R.  The crew called for clarification about these NOTAMs.  I contacted BOS Airport Authority for clarification as to why Cat D aircraft are prohibited from the approach but other Category aircraft are not.  Airport Authority/operations had no knowledge of these NOTAMs.  I also contacted BOS tower who also indicated they had no knowledge of these NOTAMs and further indicated that as far as they were concerned the only limitation was that the CAT 2 and CAT 3 approaches were not available due to snow build up around the approach lights.  The tower indicated as far as they were concerned the ILS CAT 1 approach was available.  Having received this information from the tower I assumed the NOTAM to be invalid and advised the crew of what I had learned via phone prior to departing.  I thought that with the extremely numerous number of NOTAMs in effect for BOS that perhaps this NOTAM should have been closed out but had somehow not been.  I later learned this was not the case.  The flight operated without incident.  I learned the following day that the crew flew the ILS 33 approach based on information I had provided.The following evening I had the same flight.  While planning the flight I noticed the same two NOTAMs still in the system.  I again contacted the BOS airport authority for information or clarification.  A different person tonight also had no knowledge of the NOTAM and was of no help.  I decided to try and dig a little deeper and try and find out where the NOTAMs are coming from if not the airport authority.  I contacted the Watch Supervisor at ZBW.  I explained the situation and what had taken place with tower and airport authority.  The ZBW supervisor was able to pull up the NOTAMs by the NOTAM numbers.  He did a lot of research and eventually determined the NOTAMs where valid.  He advised that the NOTAMs originated out of an FAA office in Oklahoma City and that it was his understanding that any time there is 6 inches or more of snow on the ground that ILS approaches can be affected.  He was a tremendous help and spent a lot of time tracking down the information.A number of questions come to mind:How can both the airport authority and tower have no knowledge of a NOTAM that effects an approach procedure at their airport?If 6 inches of snow can; in fact; impact the approach procedure to this degree why is this not a NOTAM that we see all the time?Why would this only effect Cat D aircraft?If a tower controller says there are no limitations on an approach but we have a NOTAM that says something different which do we follow?  It is not uncommon for tower controllers to have different information.I thought I was exercising due diligence in contacting the tower and airport authority only to; apparently; be lead down the wrong path.  For flights the next day I advised the crew not to accept an ILS33 approach and instead to plan for a RNAV (GPS) RWY 33L if an instrument approach is needed.  I would have done the same for the flight in question had I been given accurate information from the airport authority and tower.




Synopsis: A Dispatcher was confused as to the application of NOTAMed limitations on low minimum ILS approaches for BOS and contacted BOS ATC for clarification. When advised they were unaware of any limitations; the flight in question was dispatched without being given a heads up and the flight operated normally. The reporter learned the next day that the limitation (only on Category D minima aircraft) had been routinely published by FAA headquarters due to more than six inches of snow having fallen.