The Airplane Altimeter
PROBLEM:
a. An aircraft is at F.L.80. The regional QNH is 990mb. What approximate clearance has the aircraft over ground, which is 4187ft above mean sea level? (Assume 1mb =30ft.)
b. Give two reasons; apart from the altimeter being subject to instrument and pressure errors, why in answer (a) you are only able to give the approximate clearance.
The answer is 3120 feet approximately. It is approximate because the LAG error and the POSITION error are assumed to be ZERO.
This A.T.P.L. question was selected from the British Civil Aviation Authority (CAA) examination past papers.
The solution is found in the book called:
“METEOROLOGY for Airplane NAVIGATION (INSTRUMENTS)” by Grace Nsubuga Lwanga.
Page 170 to 171..
https://www.amazon.com/Mr.-Grace-Nsubuga-Lwanga/e/B07KDJ91W2
ABOUT THE BOOK:
This book is suitable for ground school studies in Commercial Pilots License (CPL) and Air Transport Pilots License (ATPL).
As a Ground School Instructor, the author successfully used the material in the book to increase the pass rate of his students in the Navigation (Instruments) exams of 1984
The book consists of the following general contents: 193 Pages; 11 Chapters; 4 Tables; 33 Diagrams; 33 Figures; and 14 Problem solutions.
The problems are selected from the British Civil Aviation Authority (CAA) examination past papers.