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Aviation History
1964
1964 - 1830.PDF
S 125 SEATS / \ /f] 1007 FLIGHT Inter- national-, 18 June 1964 TridwiC Standard VCIO DO4 Boeing 707.320 Here, and on the next page of this article, are a variety of plans of British and American airliner cabins, designed to show the number and compara- tive sizes of doors and emergency exits available to passengers. Passenger totals in oil cases are the maximum for which the aircraft can be certifi- cated. In each instance the artist has bisected the top of the cabin longitudinally and opened out the walls. The four types above are approximately to scale GETTING OUT ALIVE... This may require that the seat spacing in this area has to be opened out, and this in turn may suggest to the aircraft designer that an extra few inches on the length of the fuselage may make up for accommodation lost by the emergency-exit provision. Completely unobstructed access to all overwing exits has in fact proved to be economically impossible, and the "break-back" seat has been developed; thus, where a row of seats would obstruct an exit, in an emergency the latter can be rapidly unblocked. Tip-up seats also help to improve access. Now to take a look at some typical configurations. Both the DC-8 and the Boeing 707 (Series 120, 220, 320, 420) reap the advantage conferred by the provision of escape slides at the main entry and escape doors, and have Type Certificates permitting the carriage of 189 passengers, although in both cases the overwing exits are less than the Type II dimensions specified in Table 1. However, the main entry doors—and in the DC-8, the galley service doors—are considerably bigger than the emergency requirement calls for. As noted already, one operator—United Air Lines, who had a disastrous crash landing with a DC-8 in 1961—are not happy about carrying 189 passengers; on the other hand, Pan American have satisfied the FAA that they can evacuate 187 passengers, using the emergency exits on the starboard side only, under simu- lated night conditions, in lmin 33sec. BOAC, who conduct emergency evacuation tests on all their new types of aircraft, do not intend to carry more than 174 passengers in their 707s. As a result of their tests they have moved two window seats to give better access to the overwing exits, and have opened out the seat pitch in this region. Since the existing regulations were framed, the rear-engined aircraft has come into vogue, and this has raised the problem of the degree to which entry doors at the rear of the cabin are safe for emergency exit. On Caravelles 3, 6 and I0B there are two Type I exits forward (port main entry and starboard galley servicing) and two Type IV overwing exits on each side. This permits the carriage °f 79 passengers (or 84 if inflatable escape chutes are carried) with- out taking into account the ventral entry door. On the Caravelle Super B, one of the Type IV exits is replaced by a Type III exit, Permitting 109 passengers, or 114 with inflatable chutes, to be carried. On the Trident 1C, certificated for 103 passengers, emergency exits are generously provided. The designers felt strongly that rear doors were out of the question, owing to the proximity of the engines to the fuselage. It was decided therefore that the main entry doors, 28in by 64in, should be immediately forward of the wing leading edge and at the extreme forward end of the cabin, with Type I emergency-exit doors, 24in by 48in, opposite. This fits in well with BEA's requirement for a midships galley, providing excellent access. In BEA's arrangement for 97 passengers; with facing seat rows flanking the emergency hatches, the two 20in by 36in overwing exits are easily reached. On the Trident IE (maximum 109 passengers), the starboard midships door is deleted in order to increase seating capacity and, instead, the number of overwing exits is increased to two per side. In order to ensure that these wing exits can be reached easily, specific seat layouts will be mandatory for certification. On the standard VC10, also, the two main entry (port) doors are forward of the wing, but on the Super VC10 both the rear entry and emergency doors are aft of the wing. On these aircraft the engines are not so close to the fuselage as on the smaller two- and three-engined aircraft; but, to ensure that there would be no risk of escaping passengers being sucked into the air intakes, BAC have studied engine run-down times in relation to residual suction, and have demonstrated that, provided the engines are shut off before touchdown, intake mass-flow falls off so rapidly that there is no> danger of dragging bodies in. If the crash is unforeseen, and the pilot does not have time to shut off the engines, the chances of surviving the high deceleration forces are negligible anyway. Existing requirements are framed only in terms of doors in the fuselage sides. Should a ventral door be accepted as an emergency exit ? On the one hand, the ventral exit is probably the most obvious exit that passengers would instinctively make for (unless smoke is pouring in from that end). On the other, it tends to be rather unpleasantly close to the engines; with built-in stairs it involves a double door and is therefore not operable by a single mechanism; and, if the aircraft were to make a belly landing, the stairs would partly block the exit aperture. The Caravelle, as already noted, is adequately "exited" without taking into account the ventral door. The Boeing 727, on the other hand, has been certificated by the FAA for 131 passengers by in- cluding the ventral door, with the proviso that an emergency system is installed for opening and extending the stairs. This aircraft is an
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