747 Tanker approval


It appears that the 747 has yet to pass the requirements to be an approved tanker, and has been running on an interim approval for years.

The only reason they were issued approval this year was because of Covid.

I can’t believe they have let this aircraft fly this long on an interim approval.


That’s interesting. Does anyone know what requirements the tanker is lacking?


Quote from the NAIC Letter: “The IABS does not support any further interim approvals without
correcting some issues originally identified in the 2009 test of the system that included failure to
meet coverage level 3 & 6, retention of retardant in the system after drop, aeration of the
retardant causing trail off, and inconsistent flight profiles affecting retardant coverage.”

The Grid Test has been an on-going issue with T-944.


Thanks, I just briefly looked at that

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If memory serves correctly, when CalFire first agreed to put T944 on Contract, they require 300 gallons reserve for the trail off factor for any drop and would not certify it’s use at full capacity for that particular deficiency.

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One final thought, which I will let the Mods decide if it is appropriate but it is germane to the entire T944 program. The President of Global Supertanker is very good with the PR aspects has used that skill to convince the public at large that the 747 is being unfairly singled out for not being on Unconditional Contract instead of working to correct or acknowledge the deficiencies.

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T-944 retardant coverage issues stem from a pressurized tank system, that is also used in the C-130 MAFF’s airborne drop system. Anytime you pressurize a liquid in a tank, it will atomized upon release. Without a gravity tank system such as the other air-tankers it will have coverage problems.

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Yes, sir, I agree. What has always had me scratching my head, is that MAFFS don’t appear to have this same issue or if they do, it is not nearly as noticeable or impacting. Now, I will be the first to say that I am not an aviation expert so there may be contributing factors between the two which become more pronounced with a larger aircraft, more payload, airspeed, AGL, (except when flying on the Ranch Fire), etc. The gravity fed delivery system is a far better delivery and more consistent, IMHO, as a ground person. Additionally, the adage of bigger is not always better certainly applies to the 747. It may have it’s place and use, if they can correct the deficiencies but it isn’t the be all end all aircraft, especially for fires in rugged terrain.