Drafting Maximum Lift (Altitude-Corrected)
Maximum drafting lift from a static source: theoretical = 33.9 - elevation/1000; attainable = factor x theoretical - suction losses (factor about 2/3). A real pump cannot pull a perfect vacuum, and every 1,000 ft of altitude shaves a foot -- lift is set by atmosphere pushing water up the suction, not the pump. A planning aid, not incident command.
Formula and source
theoretical_lift = 33.9 - site_elevation / 1000; attainable_lift = pump_factor x theoretical_lift - suction_losses (pump_factor about 2/3).
IFSTA / NWCG firefighter math altitude-corrected drafting maximum lift, by name.
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