OK.
My pedantic contention was firstly, knowingly using a navigation light in contravention of the precise regulations would, if the same parameters exist in the aeronautical world as in the marine world, be cause for some attributed blame .
Secondly, as I implied, the perception of one party (the bloke in the marine lit machine) might be different from the bloke in t'other aerobeast.
I'm not sure I can put this into words without recourse to a diagram!! Sorry ... but here are the words..... S'cuse grammar.
"A"= Bloke in the incorrect navigation lit machine
"B" = The other bloke .
"A" - Heading, say North, thus his arc of green light would be showing from North round to 112.5deg (2.5deg short of EastSouthEast)
"B" Heading, say Northwest
"B" is over on "A"'s starboard side on about the 112.5 deg vector (ie bearing ESE from "A")
"B" Sees a green sidelight over on his port side (1/2 past 10)
"B" thinks to him/her self - "Ah! I can see his green. He's a crossing a/c & should give way , it'll probably come round my stern".
"A" Maybe doesn't see "B" - A potential close quarters situation arises. Or....
If "A" has seen "B", he/she possibly thinks, "Ah! It's an overtaking a/c - It is "B"'s responsibility to keep clear".
An unlikely scenario maybe, but nevertheless not impossible.
It happens lots of times at sea, even if the navigation lights are correctly fitted!)
The cut off for the navigation lights is well laid down. When undertaking a marine survey for renewal of ones Ship Safety Certificates - The surveyors check the arc of visibility of the lights. Many a time , whilst in drydock, I've had the surveyors walk round the dockside, asking for the various lights to be shown to check & verify the arc of visibility.
If the Board of Trade surveyor didn't like it he'd get us to adjust accordingly (Heavy weather, worn fittings did cause slight misalignments on a number of occasions). Either we fixed the problem by tightening bolts, hammering the brackets! or even replacing the, usually, wooden, 'blinkers' ,to enable an accurate arc to be displayed.
The navigation lights of an aircraft are similarly designed, with or without 'blinkers' to ensure correct arcs of visibility. Aircraft which fly at night should have had their navigation light fittings surveyed and inspected in order to confirm acceptance. Which I'm sure they do. - Mine hasn't got any, so I'm OK!
Now my point remains - IF a machine has been fitted with a marine navigation light , and there's an accident, then one of the ambulance chasing litigant's weapons will be that the user deliberately flouted the regulations. If the user of these very important illegal lights knew they were illegal, what else did he/she choose to ignore?
Signed: EGHHZXAC - Life's tough if you don't weaken.