This question mentions a flight that had to divert, in that case to Iqaluit (YFB).

I was wondering: in modern large airliners, what is the user interface like when diverting? How is the case of "what is the nearest airport/runway we can divert to now?" handled in the avionics displays?

Does the computer system know at all times what the nearest runway or airport is? Does that information appear when needed, or perhaps it's just continually displayed and updated at all times?

Does the system understand subtleties such as which one is best based on your current heading, altitude and so on? Or do pilots just have to quickly look up the nearest one with no special help from the avionics?

Or, is it figured out for each stage, as part of the preflight planning? Do they have it written down as part of a flight plan? Or does the crew have to program in a list of suitable diversion airports along the coming route, and if the worst happens the system will tell you which one (of that set) is nearest now?

In fact, is there just a big red button marked "Divert Now", and the plane immediately changes course to whatever it decides is the nearest and/or best diversion prospect at that moment?

To be clear, I'm talking about how it works in this sort of cockpit:

enter image description here

(To a civilian, most modern airplane controls look like that: touchscreens with some sort of graphical user interface.)

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    $\begingroup$ For more about "touchscreens", check out this question. I don't think we have a UI/UX tag as such, but "avionics" would be appropriate here. $\endgroup$ – Pondlife May 17 '17 at 19:48
  • $\begingroup$ Whether it is figured out ahead of time depends on the type of flight. For flights over populated areas (like the US or much of Europe), there is almost always a suitable alternate nearby and the pilot can just select what he feels is the best option. For flights over areas without nearby alternates (like oceanic and polar crossings), they must be selected ahead of time and exact points calculated which delineate when to divert to which alternate (for more info see Are there diversion points for southern Pacific great circle route flights?). $\endgroup$ – Lnafziger May 17 '17 at 22:43
  • $\begingroup$ so awesome! now that's how action-movie-watchers think of you guy's offices :) $\endgroup$ – Fattie May 18 '17 at 1:05

On a Boeing 777, the pilot can select to have nearby airports displayed on their navigation display (ND). It's the quickest way to get the info IMHO.

Of course this data needs to be corroborated with the nearest airport in the NavData and once a suitable airport is chosen, it can be quickly entered into the modified route - activate, execute and fly direct to.

Boeing 777 ND with nearby airports selected from EFIS Control PanelND showing nearby airports.

Boeing 777 EFIS Control Panel EFIS Control Panel with ARPT button to switch airport display ON/OFF.

  • $\begingroup$ A spectacular answer to the specific question. $\endgroup$ – Fattie May 18 '17 at 11:14
  • $\begingroup$ This answer is so amazing, even the photos are top quality and in perfect focus! HenryJohn, in the lower photo, is that whitish object actually a pen (or similar) with which you are showing us the button in question? (Or is it indeed a small .. joystick or something? It's not clear.) Thanks! $\endgroup$ – Fattie May 18 '17 at 14:58
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    $\begingroup$ That is a pen that I was using to show where the ARPT switch is. A MFD is a display that can have many different display configurations. It is true that while the pilot is flying, nearby airports will only show on their navigational display. This particular screen, adjacent to the primary flight display, can be selected to display a multitude of options such as synoptic information, ground maneuvering cam, central maintenance information and navigation data. This particular display in a Boeing 777 can be selected as either a MFD or ND. $\endgroup$ – HenryJohn May 18 '17 at 18:57
  • $\begingroup$ thanks again for this amazingly specific answer to the precise question, cheers $\endgroup$ – Fattie Jun 9 '17 at 11:14

There are a few options for this and it depends on the type of plane you are in, for the most part it looks like the information must at least be proactively navigated to in what ever NAV system you are using.

Every pilot should study their route before hand and identify possible diversions or at least understand where they are. For pilots flying common trans ocean routes there are some pre-arranged diversion airports that the pilot should know.

If you are using some kind of tablet as your source of navigation information (maps) most of the modern apps have a function for this.

If you have some kind of in panel GPS like a Garmin GNS system there is also a page for that very information.

According to this doc FMS systems may have this info as well. For example in the 737

This extremely useful page takes a couple of minutes to calculate but will list the nearest airports in the database in order of DTG.

Once again, line selection of 1R to 5R will give more useful diversion information as shown below.

enter image description here


You can also program in you alternates

You can enter up to 5 alternates here, selecting 1R to 5R against any entered alternate will show the info below...

enter image description here


The FMS will compute data to those points from the aircrafts current location.

All the diversion data is now shown based on you flying direct to this alternate from present position (VIA DIRECT). Selecting MISSED APP will show the same data but calculated from the missed approach point. Selecting nearest airports will give...

enter image description here


Even the more modern airbus cockpits contain a traditional FMS input or possibly a keyboard and mouse. To my knowledge airlines have not really adopted touch screens yet.

enter image description here


Some of the smaller panel avionics are starting to incorporate touch screens like Garmins GTN series however some pilots prefer the tactile feel of hard buttons.

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    $\begingroup$ fantastic info Dave, thanks. fascinating, "takes a couple of minutes to calculate but will" (!) is that a typo in the manual?? $\endgroup$ – Fattie May 17 '17 at 19:38
  • $\begingroup$ The "FMS" in a 737 b737.org.uk/fmc.htm ie, this .. b737.org.uk/images/fmc.jpg (!!!!) seems amazingly old-fashioned. $\endgroup$ – Fattie May 17 '17 at 19:42
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    $\begingroup$ @Fattie The aerospace/defense term for old-fashioned is proven. $\endgroup$ – Matt Young May 18 '17 at 0:55
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    $\begingroup$ Many of the systems may not be old inside. But a familiar interface is often kept to keep workflows efficient and tactical feel present. This caused a very large issue historically with the difference between eastern and western made attitude indicators which is why many companies strive for uniform control design even as technology progresses. $\endgroup$ – Dave May 18 '17 at 1:15

I believe on Garmin systems, the pilot can simply hit 3 buttons: "Nearest", "Direct-To", "Enter", and the flight computer will immediately show a line straight to the nearest airport.

If they configured their settings before, they can set certain parameters, such as minimum runway length, and excluding grass runways.

  • $\begingroup$ Gotchya. I appreciate that on "consumer" (let's say) systems like ipads, Foreflight etc, there's such a button. I guess I was wondering about "on new jumbo jets!" you know? For us civilians (see image I edited in to the question), I assume the glass on a modern cockpit is one enormous touchscreen that does everything (blue button, "fly to London", yellow button "serve dinner", green button "divert somewhere with nice weather" etc) - perhaps that's just wrong. i guess I assumed it would link right in to the autopilot? $\endgroup$ – Fattie May 17 '17 at 20:06
  • $\begingroup$ Like the field of medicine, aerospace has a "First, do no harm" principle. As in, do not divide by zero and kill everyone on board. This means that you will probably find iphone functionality in cockpits im 20 years time. The processors in an A320 cockpit are late 1980/1990 type, the type that Apple abandoned for Intel 10 years ago. If it works, don't touch it. Even the aluminium used in the structure has a paper trail tied to it that allows for tracing for faults if required. $\endgroup$ – Koyovis Jun 2 '17 at 23:39

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