During visual flight conditions, when you see another aircraft in your path, you should strive to avoid hitting it.

In shipping there are standard international rules about which way boats should turn in order to avoid each other.

Are there similar rules in aviation?


2 Answers 2


In shipping there are standard international rules about which way boats should dodge each other.
Are there similar rules in aviation?

Why yes, there are - in fact they're basically similar to the maritime rules!
They're described in ICAO Annex 2 (or for US pilots, FAR 91.113).

Basically, for aircraft of the same type (e.g. two airplanes) in the air the rules are:

  • Approaching head-on: Both aircraft alter their heading to the right.
  • Converging: Give way to the aircraft on your right.
  • Overtaking: Pass "well clear" to the right of the aircraft being overtaken.
    (The aircraft being overtaken has the right of way. The overtaking plane maneuvers to remain clear.)

The rules for converging aircraft are more complex when the aircraft are not the same type - basically the more maneuverable aircraft gives way to the less maneuverable aircraft (because something like a balloon can't really maneuver to avoid a collision) - you can read the details in either of the links above.

Also while it's not explicitly spelled out in ICAO Annex 2 (or at least I didn't see it) aircraft in distress generally trump the "right of way" rules. (This is really common sense: if an aircraft is recognizably in distress you do everything in your power to stay out of their way and help ensure a safe outcome to whatever their situation is.)

  • 2
    $\begingroup$ Also, powered aircraft give way to non-powered aircraft, regardless of maneuverability, so in theory a B737 should turn to avoid a glider... $\endgroup$
    – falstro
    Apr 26, 2014 at 7:48
  • $\begingroup$ Are those rules( ICAO ) acknowledged internationally; would they hold up in most countries? $\endgroup$
    – this
    Apr 26, 2014 at 16:07
  • $\begingroup$ @self. You would have to check the specific regulations in each country, as those define the operating rules within that nation's airspace (ICAO signatory states are allowed to deviate from ICAO standards, and there are some non-ICAO states), but these rules hold in all the countries I'm aware of. $\endgroup$
    – voretaq7
    Apr 29, 2014 at 1:11
  • $\begingroup$ @voretaq7 Thanks. $\endgroup$
    – this
    Apr 29, 2014 at 9:30

This is not answering your question directly but is relevant IMHO.

There are also rules of thumb designed to prevent aircraft from arriving at the same place at the same altitude heading in opposite directions for example:

  1. Follow line features (roads, rivers etc) by placing them on your left.
  2. The quadrantal rule for altitude selection (optional for VFR, but so is common sense). http://en.wikipedia.org/wiki/Flight_level#Quadrantal_rule
  3. Not arriving at common waypoints at "obvious" altitudes. Use 1100 instead of 1000, 1450 instead of 1500 etc.
  • 1
    $\begingroup$ If many pilots followed number 3, then it would defeat the purpose, wouldn't it? $\endgroup$ Apr 26, 2014 at 7:27
  • 3
    $\begingroup$ @deletethisaccount I think the point is that you should not be at 1000ft or 1500ft, not that you should specifically choose 1100 and 1450 as alternatives. $\endgroup$ Apr 26, 2014 at 9:16
  • $\begingroup$ Of course if everyone followed #3 the safest altitude would be the "obvious" one. Just to be clear, #3 may be common practice but it is NOT a rule. The only rule approaching a waypoint is be alert! $\endgroup$ Apr 26, 2014 at 13:13
  • $\begingroup$ @DavidRicherby Yep, that's the point. It's a bit overkill but can be useful. Where I trained, there is a particular waypoint (CPT in the UK) closeby which seems to be on every training route for x-country solos etc in the south of England. There were usually 3 or 4 craft all within a few miles of the WPT at any time and picking a random "weird" altitude does give some increased separation. $\endgroup$
    – Simon
    Apr 26, 2014 at 13:22
  • $\begingroup$ #1 is good common sense in the US (not sure re/ the UK), but I've never seen it mentioned in the regs or the AIM. $\endgroup$ Apr 26, 2014 at 22:56

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