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Air Law question

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Air Law question

Old 29th May 2021, 07:16
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Air Law question

I am re studying Air Law (after many years) in a bid to get my EASA license ( now that we’re our of EU) and am using the excellent AOPA website. However came upon an interesting question and answer.

You are flying at night, in good visibility when you notice a green navigation light on a constant bearing of 340 degrees same altitude......which of the following is correct.

Of the four choices, two stated no risk of collision and two stated there was a risk of collision, the choices being a. Do nothing because you have right of way or b. Change altitude to avoid a potential collision.

The correct answer on the website was a. No action required you have right of way, perhaps technically correct, but is it a wise course of action ? If the other pilot has not seen you and you have to assume that, why would you not act to avert a potential problem, provided of course you could safely do so. Not much point claiming right of way if you subsequently hit each other !

Any thoughts ?
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Old 29th May 2021, 08:14
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We're using the AOPA ground school for all of our students. I only see the "Readiness Certificates" that are issued, never the content or test questions, but I know it's an excellent system so far. Is it not possible to ask AOPA for an explanation?
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Old 29th May 2021, 09:32
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You're studying law. The answers are less about how the rules might work out when applied in the real world and more, only really, about what the rules say should happen.
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Old 29th May 2021, 15:24
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Remember that exam questions in 'objective' testing: require you to select from a number of fixed answers. So a personal opinion cannot be assessed. Only one answer can be correct. The answer must be wholly correct in itself, The question could be asking for just a part of the whole story. Refer back to the question with this in mind when your struggling to decide.

For the particular question with regard to lights: the three navigation (position) lights add up to 360 degrees. The red and green radiating 110 degrees each and the white tail light therefore must be radiating 140 degrees. Worth drawing this out on some graph paper to fully understand. However the answer is partly in the question. For exam technique: whenever a "constant bearing" is in the question then you must be on a collision course. Look at the question again to see if the question is regarding a 'collision' course or whether it is asking who has the 'right of way'.

For me, with regard to a right of way, the aircraft concerned is within 20 degrees of of the nose and it should be considered a head on and therefore requires a turn to the right. The question, if it is quoted correctly, is unfair because the answer requires an opinion.

Last edited by Fl1ingfrog; 29th May 2021 at 15:39.
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Old 29th May 2021, 15:44
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Originally Posted by Fl1ingfrog View Post
For exam technique: whenever a "constant bearing" is in the question then you must be on a collision course. Look at the question again to see if the question is regarding a 'collision' course or whether it is asking who has the 'right of way'.
Constant bearing of 90 degrees, both aircraft at same speed and heading. Are they on a collision course? Substitute any bearing you like - are they on a collision course? I suggest that you must get very nervous watching aircraft fly in formation.

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Old 29th May 2021, 16:24
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Originally Posted by EXDAC View Post
Constant bearing of 90 degrees, both aircraft at same speed and heading. Are they on a collision course? Substitute any bearing you like - are they on a collision course? I suggest that you must get very nervous watching aircraft fly in formation.
Substitute anything else than a perfect parallel trajectory, and they are on a collision course. I.e. the whole universe minus the exact parallel singular line.

true, they might be on collision course but with opposite vectors - leaving away from the collision point.
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Old 29th May 2021, 17:01
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Originally Posted by FlightDetent View Post
Substitute anything else than a perfect parallel trajectory, and they are on a collision course. I.e. the whole universe minus the exact parallel singular line.
Is it not possible for an aircraft on a divergent course but different airspeed to maintain a constant relative bearing?

Constant bearing is neither a necessary nor sufficient condition for a mid-air collision. At a minimum the aircraft must also be converging laterally and, if not already at the same altitude, must be converging vertically.




Last edited by EXDAC; 29th May 2021 at 17:40.
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Old 29th May 2021, 17:38
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Constant bearing of 90 degrees, both aircraft at same speed and heading.
In such a situation you would see two lights: Red/Green, Red/white or Green/white.

For exam technique: whenever a "constant bearing" is in the question then you must be on a collision course.
The term 'exam technique' refers to questions normally asked in exams, the two words speak for themselves..
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Old 30th May 2021, 04:28
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Originally Posted by EXDAC View Post
Is it not possible for an aircraft on a divergent course but different airspeed to maintain a constant relative bearing?

Constant bearing is neither a necessary nor sufficient condition for a mid-air collision. At a minimum the aircraft must also be converging laterally and, if not already at the same altitude, must be converging vertically.
If you omit the second sentence, the first stops making proper sense. I admit that.

Curious how you hit something moving across the windscreen, do tell! Tehcnically speaking, I am only trained in not coming to visual range.

Last edited by FlightDetent; 31st May 2021 at 04:23.
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Old 30th May 2021, 07:41
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Originally Posted by EXDAC View Post
Is it not possible for an aircraft on a divergent course but different airspeed to maintain a constant relative bearing?

Constant bearing is neither a necessary nor sufficient condition for a mid-air collision. At a minimum the aircraft must also be converging laterally and, if not already at the same altitude, must be converging vertically.
I take it you haven’t taken the Air Law exam.
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Old 30th May 2021, 10:29
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Originally Posted by FlightDetent View Post
Substitute anything else than a perfect parallel trajectory, and they are on a collision course. I.e. the whole universe minus the exact parallel singular line.
If the other aircraft is on a constant relative bearing of 340 and a green light can be seen then the above scenario is not possible. They are on a collision course. Simple as that
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Old 5th Jun 2021, 22:10
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Originally Posted by ShyTorque View Post
I take it you haven’t taken the Air Law exam.
No I have not. FAA has no such exam.
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Old 5th Jun 2021, 22:30
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EXDAC,

The CAA have always maintained the view that if another aircraft is on a constant bearing, there is a risk of collision. End of story.
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Old 5th Jun 2021, 22:42
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Originally Posted by FlightDetent View Post
Curious how you hit something moving across the windscreen, do tell!
I'm sure there is an infinite number of scenarios, but here is one:

I fly parallel to, right of, close to, and at the same altitude as another aircraft which maintains constant heading. I roll toward the other aircraft. The first appearance of the other aircraft in my windshield is when the nose appears in the upper left corner. As I continue the turn the other aircraft's nose moves toward the lower right of my windshield. As I get closer my view of the other aircraft sweeps down the fuselage and the last thing I see, and hit, is the tail.




Last edited by EXDAC; 6th Jun 2021 at 00:47.
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Old 6th Jun 2021, 03:44
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Thank you, no further clarifications necessary.
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