Having purchased more than ten aircraft for his own business during his 30 years in aviation, Hans Grossmann of Grossmann Air Service has published a book designed to make buying an aircraft easier. \rA series of consultations will accompany the book, during which a study of the customer's requirements and a financial plan will be made. \r"The book form carries more weight, particularly when presenting the report to banks or potential partners," said a spokesman for the company's new consulting service. "This book is not for just anyone, it is aimed at determined people who are seriously considering the purchase of an aircraft."\rGrossmann Air Service is itself considering the purchase of a new aircraft this spring, although details have yet to be finalised.