 Its volatility must be low enough to make it flash-resistant at these high temperatures.The very low volatility, and relative unwillingness of JP-7 to be ignited, required triethylborane (TEB) to be injected into the engine in order to initiate combustion, and allow afterburner operation in flight.The SR-71 had a limited capacity for TEB, and therefore had a limited number of available 'shots' of TEB (usually 16) for re-starts, and those had to be managed carefully on long-duration flights with multiple stages of relatively low-altitude air refueling and normal high-altitude cruise flight.