The second noteworthy feature was a function of the Guild navigational techniques. Since the Guild navigators "saw" rather than calculated their routes, there was no need for the elaborate observational and locational devices common to both earlier and later ships. A heighliner carried a simple radar set and a small telescope, neither of which was of any use daring traits-light operation. Thus heighliocrs traveled blind but for the drug-dreams of their navigators. We have little direct information about the size of hcighliner crews or about the conditions of travel for passengers. Since all the heighliners at Eta Ophiuchi are fitted with gymnasia and other sorts of game rooms, libraries, and rather elaborate galleys, it appears that the Guild and its employees traveled in comfort. All passengers were carried in the unpressarlzed bold, either in their own frigates and other ships or in self-contained modules.. The hold was only a network of girders and cables to which the cargo was attached, covered only by the light aluminum skin that carried the neutrino circuitry. The Guild guaranteed secure transit, but provision for life support, not to mention comfort and diversion, seems to have been left entirely to the customer, Taking into account the number of duty stations, the design of the various control systems, and similar evidence, we can estimate that the usual neigWioer crew numbered about eighty. At least five to eight of them were navigators, and the fusion plants must have required the attention of at least two mental engineers at an times. The remaining sixty or so crew members were pilots, shut-tie crew, life support technicians, financial and banking staff, cargo manipulators, and so forth. The speed of the heighliners insured that no voyage within the limits of the Imperium would last too long. The fastest known heighliner transit was made in 12717, from Ix to Aiglon, 8138 light-standard-years, in nineteen days, two hours, twenty-one minutes, forty seconds-a "speed" of about 63.4 l.s.y. per hour. Most heighliners achieved a performance no better than sixty percent of that during normal operation. A heighliner's energy requirements were obviously very large. As much as twenty percent of a heighliner's gross mass was fuel (H20) for its fusion plants; during longer transits refueling was occasionally necessary. Waste heat was always a problem for the heighliners. As much as possible was passed through the outer planar fields as X-rays, a technique that made the departure of a heighliner rather a dangerous event to observe. Ordinarily the Guild did not orbit a heighliner closer to a planet than 150,000 kilometers. A malfunction of the waste-heat disposal system was the cause of the worst recorded disaster in the Guild's history. In 11286, on a transit from Harmony to Gamont, the planar fields of the heighliner Salience overloaded. A transparency reversal resulted, sending intense X rays inside, rather than outside the ship.