B737-700
Dispatch Dispatch 35
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Work Refused
Company Policy; Aircraft; Weather
A review of my desk's MEL items at shift start showed (ac#) with a #2 ENG BLD AIR SHUTOFF VLV (PRSOV) INOP MEL 36-X-XX.  Knowing this was an AOB [at or below] FL250 and no icing restriction; I determined that icing conditions would likely exist for the flight (FLIGHT A) that (AC#) was scheduled to operate. There was a low system centered on SAN that was bringing moisture up from the Gulf of California; up the east side of LAS; and then curving over East-to-West over central NV; creating orographic storms along the Sierras; and pushing the blowoff further west over central CA.  NWS showed icing PIREPS at 14K in the RNO area; and another at FL210 west of BTY.  'Connecting the dots' between these two points along the Sierras showed more weather; that; while not a solid line was still indicative to me that icing conditions were likely in-between.  I advised [Manager] that I wasn't going to be able to take (AC#) on the flight to LAS.  He didn't seem receptive of the news; and shortly thereafter; I was approached by a Chief Dispatcher as to why I wasn't taking the aircraft; and that the other Dispatcher (I presume) had told him he didn't see the weather problem.  I replied that although (Flight A) could depart in the clear and likely be over everything before his top-of-climb; there was still weather on the SUNST3 arrival into LAS that he would have to transit.  I also told Chief Dispatcher that I was planning to get more PIREPS; but that I thought the operation was doubtful.  Flight (flight C) RNO-LAS later reported icing where I had suspected it.  I then confirmed to another Dispatcher that I couldn't take (AC#) to LAS; and offered PHX as an alternative.  He called me back asking what the problem with LAS was; as his 'cursory glance' of the weather didn't suggest a problem.  I responded that I had accomplished more than a 'cursory glance' at it; and had a supporting PIREP.  He asked if we could operate to LAX; and even though icing was now also confirmed north of SoCal (also where I had observed it earlier) I told him we could.  I stepped flight (flight D) to LAX down to avoid the icing conditions; and later briefed my PIC.I could halfway understand the desire to 'confirm' the icing assessment were it being made by a relatively 'new' Dispatcher; but with a total of 35 years of experiences under my belt; I would like to think a Dispatcher or Chief should be able to take my assessment for exactly what it is; and not be received as an inconvenient reality that's going to cause someone some work to come up with a new plan.  It should be noted that that these people are not exercising the responsibilities of their license in their respective positions; and none of them run the risk of any potential FAA certificate action should their rosy assessments later be disproved once an aircraft experiences the conditions prohibited by the MEL provisos.  Given FAA's interest in our MEL compliance; and our future ability to continue using MEL relief; I would hope that those in management can readily agree that the potential consequences of operating a no-ice aircraft into icing conditions pale in comparison to some improperly deferred POBs.  The office culture must change; and ignoring realities in favor of desired outcomes are in nobody's best interest; least of all; all the new dispatchers we have coming online that might easily be pressured into accepting a bad situation.
Dispatcher reports pushback from the Lead Dispatcher when he refuses to dispatch an aircraft; with an MEL restricting flight into icing conditions; into what he believes are icing conditions.