The Canadians provided an NPA in 2001 that attempted to address this situation; the explanatory text is illustrating:
Issue:
Aircraft operating under the visual flight rules (VFR) are required by the Canadian Aviation Regulations (CARs) 602.114 - Minimum Visual Meteorological Conditions for VFR Flight in Controlled Airspace and CAR 602.115 - Minimum Visual Meteorological Conditions for VFR Flight in Uncontrolled Airspace, to operate with "visual reference to the surface".
The term "visual reference" is not defined and there have been many accidents where aircraft have crashed due to pilot disorientation caused by a lack of visual cues. These situations typically occur during night VFR flight or flight over featureless snow covered terrain or frozen lakes.
Justification for Change:
The single most important instrument for maintaining aircraft attitude is an attitude indicator. As can be seen from the regulations above, any aircraft may be operated during the day without an attitude indicator and a private aircraft operated at night without one. In reality, virtually all aeroplanes have attitude indicators, as do most helicopters. The problem more likely lies in pilot training and judgment than in equipment shortcomings.
There is a common misconception that if the minimum visibility criteria are met, then conditions are suitable for VFR flight, particularly during daylight. There is also general agreement among pilots that flight in conditions with any reduction in visibility on a dark night over uninhabited terrain is not VFR. The difficulty in rationalizing these different points of view is in determining what constitutes visual reference. Some jurisdictions have used the concept of a "visible horizon".
The United States’ Federal Aviation Regulations (FARs) Part 135 (equivalent to CARs subparts 703 and 704) mention "surface reference" only for helicopters as follows:
"135.207 VFR: Helicopter surface reference requirements - No person may operate a helicopter under VFR unless that person has visual surface reference or, at night, visual surface light reference, sufficient to control the helicopter."
Jane’s Aerospace Dictionary uses the following definition:
"visual reference - Earth’s surface, esp that clearly identified and thus giving geographical position as well as attitude and orientation guidance, used as a reference in controlling flight trajectory, if necessary down to touchdown."
These two references address the aircraft’s attitude and orientation with the Jane’s Aerospace Dictionary definition additionally requiring geographical information.
The CARs, Part VII, Regulations for night VFR indicate that electronic means of navigation are acceptable and the terrain and wide expanses of water in Canada may make determining geographical position by reference to the surface difficult.
Transport Canada has been addressing the issue of pilot judgement in various ways and these hopefully will have an effect on inappropriate use of the visual flight rules. It is felt that clarification of the term "visual reference" will have the effect of preventing flight when conditions do not fit the intent of these rules. There will no doubt always be an element of subjectivity when assessing if visual reference is adequate, however, incorporation of the following suggested change may assist in guiding pilots and supervisors in conducting operations in difficult conditions.
The subsequent change in regulations inserted the following text:
No person shall operate an aircraft in VFR flight within uncontrolled airspace unless
(a) the aircraft is operated with sufficient visual referenceto enable a pilot to maintain the aircraft’s attitude and orientation with reference to the earth’s surface by the use of visual external cues;
...
It is not clear that the problem is solved with the addition of this text because it still relies upon judgement that
cannot be made
before flight and therefore dispatch criteria is not established.
The amount of external visual cues is also related to the handling qualities of the aircraft. As has been stated in the 'EC225/New Procedures' threads, an aircraft that has sufficient flight control augmentation can be flown safely with very few external references.
To paraphrase Gomar Pylot 'there are sufficient visual references until there aren't'.
Jim