CHIEF INFLUENCE

Dominion, Volume 31, Issue 287, 31 August 1938, Page 8

CHIEF INFLUENCE

Taxiing Requirements On Harbour METEOROLOGICAL DATA Committee Takes As Broad A View As Possible The services of a tender would be necessary for discharge and embarkation on any day when wind was of sufficient velocity to render it dangerous for the fiying-boat to be tied up to a pontoon, the report states. To safeguard the machine when a tender is in use, it might be necessary, even in the comparatively calm waters of Evans Bay, to provide an artificial shelter in Which the flying-boat could be moored. If this were done, the committee is of the opinion that there would be no risk in landing and embarking passengers as far as sea conditions are concerned, but the rapidly changing direction of strong northerly winds might drive the flying-boat against the tender with consequent damage to the hull or wing tip floats. The aircraft will require to taxi to and from moorings and to manoeuvre prior to take-off, which will involve moving across wiud and turning. While the maximum strength of winds In which marine aircraft can taxi with safety has been variously stated by constructors and operators as from 20 to 40 m.p.h., attention has been drawn to the danger of turning in high winds on account of possible damage to wing tip floats which might lead to loss of the aircraft. Aircraft not fitted with wing tip floats are understood to be even snore unstable and liable to accident in taxi-ing across wind. Controlling Influence. Taxi-ing requirements have, therefore, been deemed to be factors exercising a controlling influence on any decision as to the suitability of Wellington as a terminal. Study of meteorological data over a period of two years indicates that postponement of scheduled departures from Wellington with probable cancellations might occur ou up to 50 days per annum, due to the risk of handling the aircraft on the water on these days. This risk would be incurred also after alighting. In arriving at these conclusions, tlie committee wished to take as broad a view as possible consistent with an adequate margin of safety, and assumed a maximum permissible wind ot 40 m.p.h. for taxi-ing. It was also assumed that departures would be made between 6 a.m. and 0 a.m. and arrivals between 3 p.m. and 6 p.m., and in compiling the meteorological information it was noticed that, in general, conditions’ were more favourable between these hours than at other times during the day or night.

Alighting And Take-oil.

A flying-boat can alight on rougher water than it can take off from. The committee is agreed that in so far as height of waves is concerned, machines could land in Evane Bay with regularity. It has also been established that conditions of visibility are generally satisfactory. There is, however, the aspect ot strength of ■wind, and change in wind direction and turbulence caused, by high ground, particularly in the frequent stii'ong winds from the northwest. In these conditions, great care and Skill would be required! of the pilot. . The concensus of technical opinion received by the committee is that the maximum safe height of waves in which aircraft could take-off is slightly over three feet. Gustiness or sudden change of wind direction under rough water conditions would add to the difficulties, and could make take-off dangerous owing to possibility of damage to wing tip floats and hull. The committee is ot the opinion that on the d'ays when taxi-ing would involve a risk, actual take-off would also be delayed. Tlie committee is of the opinion that, given the assistance of normal aeradio aids, aircraft could approach or (apart from wind ami sea conditions) depart from the Wellington area with a satisfactory degree of regularity throughout the year.