# Why is port-starboard terminology used in aviation?

I am not a pilot - just a student & play Ace Combat sometimes

Intrigued by the words Starboard & Port-side I researched why these words are used instead of the simple ones, I found that:

Port is derived from the practice of sailors mooring ships on the left side at ports in order to prevent the steering oar from being crushed. src

Also, quite notably:

Since port and starboard never change, they are unambiguous references that are independent of a mariner’s orientation, and, thus, mariners use these nautical terms instead of left and right to avoid confusion. When looking forward, toward the bow of a ship, port and starboard refer to the left and right sides, respectively.src

I see both the reasons are derived upon the concerns of the marine world - so why do we use them in aviation world?

This is specially interesting if we consider the fact that flying machines can manevur in all 3D, newbies (me) tend loose track of my VS. plane's left & right when not in level flight. Then why the added confusion?

• in non level flight port and starboard are usually still in the same place, it's only when you go inverted that it's more confusing. – ratchet freak May 27 '15 at 8:25
• Related: Viking steering boards and terminological conservatism - Also, navy aviators don't use these terms for obvious reasons. – RedGrittyBrick May 27 '15 at 8:30
• I have never heard port and starboard used in aviation. Airfast 123, turn left heading 350 degrees. Airfast 123, traffic 4 miles, same level crossing left to right. Airfast 123 exit the runway 3rd exit on the left. – Simon May 27 '15 at 9:11
• @Sami Where? I worked in military maintenance (RAF and BAe) for 20 years and never used port and starboard. Left engine(s) were called left and number 1 or 1 and 2 for 4 engined craft. We always referred to left and right gear etc, The Boeing and Airbus checklists I can find with a quick search all refer to left and right or engine number, – Simon May 27 '15 at 9:48
• @Sami i echo Simon's comment for commercial ops. "Engine #1" or the "right main gear", or the "left pack", etc is how we referred to things to everyone including maintenance. Maintenance logbook entries likewise would say things like "serviced oil #2 engine". No use of port or starboard to be found anywhere. – casey May 27 '15 at 13:58

It isn't (much).

Ships are the most similar thing to aircraft that existed before them, so it made sense that aviation took over many terms and conventions from seafaring (the pilot in command is called captain, the cockpit is the flight deck, distances and speeds are given in nautical miles and knots etc.)

However since there is no physical port in an aircraft to serve as reference (most aircraft have doors on both sides), everybody has to learn to give the sides relative to the direction of flight and then it does not make sense to teach them new words when they already know “left” and “right”. So “port” and “starboard” are only used where there is a naval tradition.

I know British military aviation (RAF) used it (in wartime stories and documents it is common, but according to Simon's comment it is not common any more) and the US Navy uses it with ships, but I don't know to what extent they apply it to aircraft.

However, it remains popular in simulator games, presumably because it is catchy and unusual and using jargon makes people feel special.

• Thanks, especially for pointing out remains popular in simulator games, presumably because it is catchy and unusual. – RinkyPinku May 27 '15 at 11:22
• Minor nitpick not really relevant to the answer as such: "Captain" is a rank, in this case an airline rank, just as it is a rank on a ship, and a rank in the military. You can be a captain of the army and never have set foot on a boat. You can still be a captain without being PIC. Sometimes there are two captains up front, but only one of them is PIC. When I fly, I'm the PIC, but I'm not a captain (there is no captain in my case). I'll crawl back under my rock now. – falstro May 27 '15 at 14:48
• @falstro 'Captain' is also a position of responsibility on a boat or plane. You can be the captain of a boat or plane, even in the military, without holding the rank of Captain. And while 'PIC' is the normal terminology, the position is sometimes also referred to as 'captain'. – DJClayworth May 27 '15 at 16:54
• @IanF1 I've never heard anyone specifically avoid using it, its just not very common. As for taxiing, we don't do any of that on our own anyway. Every movement on the flight deck is highly choreographed by our yellow shirts, including the degree to which we move our nose wheels. – Rhino Driver May 28 '15 at 4:28
• The use of nautical miles and knots has less to do with the shared sailing heritage of flight and more with the practicalities of navigation. They are logical and useful units: One nautical mile is one minute of arc, so sixty nautical miles is one degree of position. If you're crossing an ocean at propeller speeds with nothing but a sextant, a stopwatch, your airspeed, and your charts that direct correspondence is very useful, as it was for mariners who only had a sextant, an hourglass, and a chip log to update their position on the chart. – voretaq7 Dec 2 '16 at 6:09

The greatest value of port and starboard over left and right is when you have people facing multiple directions. port and starboard are always vehicle centric directions (as are fore and aft) and remain constant regardless of which way you are facing. In this context right and left therefore apply to the people (or other things that have left sides like consoles) in the vessel. Therefore it is perfectly reasonable for a flight attendant to turn left, starboard and north all at the same time. A pilot should not try to do this while working. This distinction is less useful if the craft is not big enough for those inside to move, and more useful when you our vessel is large enough to have a map of the interior.

• This makes sense, good point. – Peter Jul 13 '16 at 8:47
• I like Hildreds reply, makes good sense. In another words, the only time port / Starboard might be justifiably used on an aircraft, would be in the case of a spacecraft such as the fictional USS ENTERPRISE , (granted its shape isn't ideal for this example, but you see the point), in an aircraft this large and with its complex layout , left and right could be confused as people (crew and officers) can move about freely and would be assigned to workstation at various locations, yet still move about the ship freely and often enough that right and left could become too confusing; hence the need fo – user16655 Aug 29 '16 at 17:53

This shows up more often in engineering documentation than aircraft operation I've observed.

For example: you sometimes see schematic labels like "STBD NAV LT" (starboard nav light)

This is helpful because when you say "left nav light", a reasonable question is 'whose left?'. PORT and STBD, FORE and AFT completely remove the ambiguity.

• This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review – Ralph J Aug 30 '16 at 4:40
• @RalphJ I have edited the answer to more directly address the question. Hopefully this answer provides context that others have not. – Daniel Aug 30 '16 at 5:35

A lot of nautical terms made their way from naval architecture into aviation. For instance the vertical coordinate system used in aircraft design is still designated WL for "Water Line", straight out of shipbuilding. Some habits are hard to break, I guess.

"However since there is no physical port in an aircraft to serve as reference"... this is not a valid explanation. A ship underway doesn't have a port either. We rely on Vehicle centric Port and Starboard and use left and right with respect to the persons orientation. If a person were standing looking at an aircraft and an engine caught fire and they said over a comm device that the left engine is on fire... how do you know he's not talking about the engine to his left... simple yes, but it does illustrate a point in the nautical term usage.

• Actually, they'd refer to the #1 or #2 engine (or the #3 or #4 as appropriate). Backing a C-130, the Loadmaster gave directions as "turn toward #1" or "turn toward #4." Inside, the usual frame of reference for airline crews is "captain side" or "first officer side" since walking down the aisle, "your" left & right is opposite the aircraft's left & right. I've never seen or heard port/starboard terminology in aviation, but I've only been doing it for about 30 years total -- there's lots of history that predates me. – Ralph J Jul 13 '16 at 5:21
• Hello Jim, welcome to Aviation.SE! – DeltaLima Jul 13 '16 at 6:53
• @RalphJ It is (was?) used in the Royal Air Force when talking about some equipment, e.g. the port and starboard pitot static vents. Left and right were not used then as they would be ambiguous. – Simon Jul 13 '16 at 9:04