However, any aircraft operating under VFR must have the required equipment on board, as described in FAR Part 91. 205 ( which includes instruments necessary for IFR flight ); but the view outside of the aircraft is the primary source for keeping the aircraft straight and level ( orientation ), flying where you intended to fly ( navigation ), and for not hitting anything ( separation ).

However, there are still minimum weather conditions that must be present in order for the aircraft to take off and land ; these will vary according to the kind of operation, the type of navigation aids available, the location and height of terrain and obstructions in the vicinity of the airport, equipment on the aircraft, and the qualifications of the crew.

However, there have been attempts to enhance and re-popularize LORAN, mainly to serve as a backup and land-based alternative to GPS and other satellite navigation systems.

However, an Icelandic law text gives a very specific explanation of " eykt ", with reference to Norse navigation techniques.

However, there are exceptions: some navigation systems use geographic south as the reference plane.

However after the revolt of the seven northern provinces ( 1568 ), the Sack of Antwerp ( 1576 ), the Fall of Antwerp ( 1584-1585 ), and the resulting closure of the Scheldt river to navigation, a large number of people from the southern provinces emigrated north to the new republic.

However, simple dead reckoning is still widely used by civil aircraft not equipped with GPS or radio navigation aids.

However, Strict Constructionists ( those who believe that the Constitution must be given the narrowest possible construction ) hold a different view of the meaning of Commerce Clause as established in Gibbons that it was limited in scope because the decision could be interpreted to say that navigation only pertained to the federal Commerce Clause because it was necessary to business as it allowed for the interstate transportation of goods.

However, the remaining locks, which provided through navigation on the unrestored central section, are largely derelict or have disappeared, and the Trust continues to work towards restoring these and other obstacles to enable boats to navigate the whole river.

However, they did not provide navigation outside of the beams, and were thus less flexible in use.

However, the building of the Manchester, Sheffield and Lincolnshire Railway line parallel to the canal ( 1849 ) left much of the navigation redundant, and the Worksop to Chesterfield stretch ceased to serve commercial traffic in 1908, when problems with mining subsidence necessitated the closure of Norwood Tunnel.

However, some academics also argue that the Vikings developed more tangible means of navigation.

However, with one eye on the developing railway network, in the 1820s the northern section of the canal between Braunston and Hawkesbury Junction was straightened out to reduce navigation time.

However, " Bridgewater " supporters point out that the last quarter-mile of the navigation is indeed a canalised stretch of the Brook, and that it was the Bridgewater Canal ( less obviously associated with an existing river ) that captured the popular imagination and inspired further canals.

However, as with almost all vessels of any culture before the late 19th century, the accuracy of magnetic compasses aboard ship, whether from a failure to understand deviation ( the magnetism of the ship's iron fastenings ) or poor design of the compass card ( the standard drypoint compasses were extremely unstable ), meant that they did little to contribute to the accuracy of navigation by dead reckoning.

However the inconvenience of having to continuously change bearings while travelling a great circle route makes rhumb line navigation appealing in certain instances.

However, the United States Navy had a distinct need for just such a system, as they were in the process of introducing the TRANSIT satellite navigation system.

However, about upstream, in the town of Perrysburg, Ohio, the river becomes much shallower and supports only recreational navigation above that point.

However, the rise in marginal product means that the workers use other means of production method, such as in loading, unloading, navigation, or around the clock continuous driving.

However as the plan to build this section was cancelled in 1798, the isolated feeder and a stretch of navigation between Ffrwd and a basin in Summerhill was abandoned.

However, several noted that the training of the aircraft pilots for night formation flying and navigation was far from satisfactory.

However, there is currently very little or no regular passenger navigation on the Sukhona.

However, it is deep in the navigation channel which has been dredged for lake freighter passage.

However, new techniques in offshore construction and the automation of lighthouse illumination made it possible to build a navigation aid on the shoal itself.

However, it was not of innocence in general that I was speaking, but of perhaps the frailest and surely the least important side of it which is innocence in romantic love.

However, in this case as elsewhere it was necessary to arrive at a single standard to be applied to all situations, representing an averaging of conditions, and thus to fix particular points in time which would be considered the dividing points between daytime and nighttime conditions.

However, the nonspecific staining by the Af in tumor sections was considered bright enough to be confused with the staining of small amounts of WTV antigen.

However, all admitted that the `` hindsight '' was not altogether lost.

However, she was able to relax and yield to the moment.

However, in this case the district manager was led to see the errors of his ways.

However, there was no real question of the justice of creating a strong Poland, both industrially and agriculturally, and one unplagued by large minorities of Germans or Russians.

However, the sovereign was not Hobbes' absolute monarch but rather the parliamentary sovereign of Austin.

However, a similar privilege was not specifically provided in section 168 for a person acquiring emergency facilities.

However, the Attorney General of California, at the request of the Secretary of Labor, sought to have the jurisdiction over the issue removed to the Federal District Court, on grounds that it was predominantly a Federal issue since the validity of the Secretary's Regulation was being challenged.

However, the Federal Court held that since the State had accepted the provisions of the Wagner-Peyser Act into its own Code, and presumably therefore also the regulations, it was now a State matter.

However nothing on four legs was supposed to be faster than a lion over a short distance, unless it was a cheetah.

However, it was virtually impossible to screen the mob outside, even if Bonner had manpower available for the purpose.

However likely it was, Pauling said, he couldn't limit himself to it.

However, Haney knew it was not a dream.

However, the confession, which was the only evidence against him, was retracted before the trial.

However, compared with March 1960 new car sales of 4,441, this March was off 23 per cent.

( However, there is little evidence that the late Lumumba was a Communist.

However, lacking requested reinforcements from McClellan, now commanding the Army of the Potomac, Pope was soundly defeated at the Second Battle of Bull Run in the summer of 1862, forcing the Army of the Potomac to defend Washington for a second time.

However Copperhead rhetoric argued that emancipation was a stumbling block to peace and reunification.

However, Plato reports that syntax was devised before him, by Prodicus of Ceos, who was concerned by the correct use of words.