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On a modern aircraft carrier, the landing area is not aligned with the axis of the ship.

Given this part of the ship needs to be asymmetric, why do most (if not all) angled flight decks point to the left side of the ship (and not the right)? Is there any advantage to favor this side?

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    $\begingroup$ I think it allows them to launch and land aircraft at the same time. By having them land a different direction than launch (they launch off the front I believe (in line with the ship)) a go around remains possible. I am not 100% sure of this so I will let someone with more knowledge weigh in. $\endgroup$ – Dave May 26 '15 at 15:30
  • $\begingroup$ @Dave - That's pretty much it. The angled deck also allows for additional catapults (which, because they cross the landing area, are only used during an emergency "scramble") but this is secondary to maintaining the ability to bolter. $\endgroup$ – KeithS May 26 '15 at 15:48
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    $\begingroup$ The comments and answers do not answer the question which is "why port?". The OP knows why it's angled, just not why the superstructure is on the starboard side. $\endgroup$ – Simon May 26 '15 at 15:50
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    $\begingroup$ Is this question asking why decks are angled to the left, or why superstructures are on the right? While partially related, those are two separate questions and there appears to be confusion about which is the actual question. $\endgroup$ – Rhino Driver May 26 '15 at 17:47
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    $\begingroup$ It seems the best answer today is from Mark. A study was conducted, the results were taken into account for the choice. $\endgroup$ – mins Jun 23 '15 at 11:01
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Farhan's answer covered why the deck is angled in the first place. As far as why the landing area of the deck points left instead of right, this is for several reasons:

  • Angling to port makes the most use of the deck area behind the catapults. Angling starboard would require the catapults to be shifted left off the centerline of the carrier (yes, the carrier does have two additional catapults on the port side, but these can't be used while the carrier is retrieving aircraft, which is more often than you'd think as the carrier maintains regular patrols).

  • Angling the landing strip toward the "island" (conning tower) of the carrier just doesn't sound like a good idea when you say it. That goes double when you realize the carrier is underway while you're trying to land on it, and therefore you have to lead the landing strip a little. If you don't, you'll end up "behind" the ship and the landing strip. With the landing strip angled to port, a plane on a "lagging" approach (lined up "behind" where the carrier's going to be at touchdown) will have a relatively clear path off to port for a wave-off. Angled to starboard, a plane that's "lagging" the carrier would be pointed right at the tower.

  • It would be possible to mirror the entire deck layout; island to port, landing area angled starboard. The reason the island is on the starboard side is primarily convention; all U.S. Navy aircraft carriers ever built have been either flush-decked or have had the island to the right. That's thus a familiar sight picture for naval pilots across all eras, and easy to train to. A new carrier design doesn't get the luxury of a whole new crew trained an entirely different way; the Navy's been training pilots since 1910, they've been landing planes on boats since 1927, and they'll do it they way they've been doing it for 88 years, thank you very much.

    The Imperial Japanese Navy commissioned two carriers, Akagi and Hiryu, with island-left designs, fielded with the idea that the island-left carrier would sail in formation with an island-right carrier in the same flag group, with opposing traffic patterns that didn't conflict. This procedure never materialized in practice; most carrier groups in both Japanese and U.S. fleets ended up with a single carrier due to their high cost and lower total number, a pattern that continues today, and even when two (or more) carriers were close enough to be called part of the same naval group, they typically maintained a wide enough spacing to permit a left-hand pattern for both ships.

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    $\begingroup$ I think the third bullet point actually answers the question. The entire answer, though, is well written and informative. $\endgroup$ – FreeMan May 26 '15 at 16:17
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    $\begingroup$ I would generally agree with point number 3, but points 1 and 2 are inaccurate. The port catapults, known as the waist cats, are used all the time and cat 4 is actually the only cat on centerline in the Nimitz class. Also, the carrier is always underway during launch and recovery. You also never lead the deck, you should only reference the deck for lineup. I'm not sure what you mean by a lagging approach, but if you grossly overshoot the centerline during the approach turn you'll get waved off on the starboard side of the ship, the same would hold true if the decks were reversed. $\endgroup$ – Rhino Driver May 26 '15 at 18:11
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    $\begingroup$ The 3rd point by itself answer the question. But why do the US Navy decide to built the island on the right? Why does this convention still influence the carrier design several decades latter? $\endgroup$ – Manu H May 27 '15 at 12:30
  • $\begingroup$ Wild guess here, but in an emergency it is probably easier for a pilot to identify a rough approach angle of all carriers are built the same. After all, the ship might have turn round in the time you where away from it. $\endgroup$ – Diego Sánchez May 27 '15 at 18:21
  • $\begingroup$ @ManuH Remember, at no point was there a clean break in carrier design. New designs always enter service alongside existing designs; also, pilots on the new carriers were trained on the old ones. So, keeping consistency with other ships currently in service will mean this sort of decision will last way past when the ships where it was established leave service. $\endgroup$ – cpast May 28 '15 at 4:02
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Why is the deck of an aircraft carrier angled to the left? Because the island is on the right.

Why is the island on the right? Because studies on the HMS Furious showed that pilots tended to turn left during an aborted landing.

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  • $\begingroup$ Why this answer is not the selected one?? It goes directly to the subject and clarifies that the choice wasn't arbitrary, out of habit only. $\endgroup$ – mins Jun 23 '15 at 10:57
  • $\begingroup$ This is the correct answer. HMS Hermes was the follow-up carrier to the HMS Furious and the first with an island, and was originally designed with two islands, later revised to one on the starboard side because of the experience with pilots turning left after an aborted landing, and to give increased width to the flight deck. The following is the reference given from the HMS Hermes Wikipedia article, and is a very good book on the subject. Friedman, Norman (1988). British Carrier Aviation: The Evolution of the Ships and Their Aircraft. Annapolis, Maryland: Naval Institute Press $\endgroup$ – Jon Story May 18 '16 at 22:09
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The innovation of the angled flight decks gives several key advantages:

Most notably, it is far safer for carriers to land aircraft on angled decks that point away from the superstructure, ground personal and aircraft parked forward. This greatly reduces mishaps involving aircraft crashing into people and objects on the deck. The reason the landing area is canted to the left is because the superstructure is on the right. For clarification, the superstructure is always on the right. The carrier landing pattern has remained constant for decades so that every approach to the carrier will remain as constant as possible.

Edit: To take it a step further, when the decision was first made to place the superstructure on the right side it was likely because the carrier pattern was already a left hand pattern. Its worth noting that the standard traffic pattern is a left pattern as well, and a superstructure on the left side, during a left hand pattern, would partially obscure the landing area from view during the downwind and approach turn.

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    $\begingroup$ Wikipedia cites a book from the Naval Institute Press that traces the decision to put the island of HMS Hermes (the first carrier with an island) on the starboard side in part to the fact that pilots already preferred to turn to port on a missed approach. $\endgroup$ – cpast May 26 '15 at 21:31
  • $\begingroup$ @cpast well, there you go, naval aviation doesn't like change and the pattern has been the same forever $\endgroup$ – Rhino Driver May 26 '15 at 21:32
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The answer lies in the same article section you referenced. There are two animations there, on the right.

Animation

As you can see in this animation, the longer runway is for landing. If an aircraft could not stop, it needs to take off again. That is the reason aircraft carriers have the landing strip angled so that it will not interfere with aircraft which are about to take off or the parked ones.

Simon clarifies that OP is specifically asking about why landing runways are not pointed towards the right/starboard side.

While the island1 is usually built on the starboard side of the fight deck, the Japanese aircraft carriers Akagi and Hiryū had their islands built on the port side.

The reason might be more of a tradition that reasons behind it. Please note that there very few aircraft carriers in the world, and only a few countries have it. So there is not a big competition or difference of standards in this area.


1: The superstructure of a carrier (such as the bridge, flight control tower) are concentrated in a relatively small area called an island

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  • $\begingroup$ And if the cable snaps then the plane ends up besides the ship instead of under where it can destroy the propeller (pilot will eject either way) $\endgroup$ – ratchet freak May 26 '15 at 15:47
  • $\begingroup$ This doesn't answer the question asked. $\endgroup$ – Simon May 26 '15 at 15:51
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    $\begingroup$ Why all the crossed-out text? If it's not supposed to be there, delete it. If it is supposed to be there, let me read it. $\endgroup$ – David Richerby May 26 '15 at 22:13
  • $\begingroup$ @DavidRicherby I think it's better to keep this crossed-out text as some comments refered to it (and it is made to be readable). $\endgroup$ – Manu H May 27 '15 at 12:33
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    $\begingroup$ @DavidRicherby I think this usage of crossed-out text has already been discussed multiple times on meta.stackexchange.com The good way for Farhan should have been to delete this answer and re answer the question $\endgroup$ – Manu H May 27 '15 at 13:03
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Why always the port side? There's no technical reason so it can only be convention - for example several carriers operating together could steam in the same direction and launch their aircraft in the same direction too. The aircraft would be on (approximately) parallel paths so would not have to take special action to avoid each other.

It also occurred to me that the bridge would be always on the right/starboard, docking facilities might be arranged to take advantage of this...

HMS Hermes was apparently the first carrier with the "control tower" (Island) to starboard. This may be the origin of the convention. The link states that pilots prefer a port turn on an aborted landing...

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  • $\begingroup$ The technical reason is that the deck is angled away from the superstructure which is always on the right. This greatly reduces mishaps. $\endgroup$ – Rhino Driver May 26 '15 at 16:08
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    $\begingroup$ But why is the superstructure always on the right? This is what the original question is all about. One of the comments by @Simon seems to give the only possible reason so far (it may favour the left-seat pilot) $\endgroup$ – Andy May 26 '15 at 16:31
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Prop planes used to (and still do today!) drift to the side opposite to the propeller rotation direction during take-off. And while it's true that the first carriers were flat-decked (no island, no banking) many pilots begin their training with prop planes.And there were some crazy 50's turboprop carrier operated planes like the A-1 in times immemorial when jets were not quite established as the future of sea-borne aviation. One might be forgiven to assume that the first "island" carrier designs originating back then had something to do with allowing a quick take-off with the rudder straight compensating for the drift by angling the deck. And as the layout was proven and found good...Just my two cents.

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  • $\begingroup$ Hi and welcome to Aviation.SE! do you have any reference for your assertions? $\endgroup$ – Federico May 27 '15 at 10:32
  • $\begingroup$ you have posted no link :/ (also, consider putting any source you might have in your answer, not in a comment) $\endgroup$ – Federico May 27 '15 at 10:42
  • $\begingroup$ sorry, I'm new to this...[link] (youtube.com/watch?v=ur18PF-6hIc) at 17:38 please observe the F6F Hellcat ,although launched on a catapult, still shows heavy left banking (being heavy ,all filled up with ammo and fuel etc while accelerating). Aircraft were launched in waves at the time, and it was not uncommon to have multiple launch and landing events simultaneously. Imagine that of all those aircraft- the ones that took off were subjected to unintentional heavy left banking, while the ones that landed -with engines close to idle- were not so much. $\endgroup$ – Axel Morisson May 27 '15 at 10:47
  • $\begingroup$ @Federico OP said drift opposite propeller rotation. It is more than just an assertion when you state the cause. $\endgroup$ – paparazzo May 27 '15 at 10:59
  • $\begingroup$ @Blam doesn't change the fact that it does not provide any reference. $\endgroup$ – Federico May 27 '15 at 16:44
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At this point in time it's because all carriers in commission have their islands to starboard, so all carriers will continue to have their islands to starboard. From a naval engineering standpoint there's no reason to prefer having the island to starboard vs. port, but from a pilot training standpoint it's important to minimize the differences between carriers in order to minimize pilot confusion.

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Another factor: Consistency. Pilots might have to land on something other than their home carrier. Carrier landings are already very exacting flying, learning one pattern is better than learning two.

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protected by Farhan May 27 '15 at 16:31

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