him225

Use of dome lights

Recommended Posts

How often and in what phases are cockpit dome lights used in a real airliner? Are these turned on during cruise? My guess is they hinder eye vision outside the window during night and might not be a preference except when aircraft is parked at gate. Are there any restrictions as well on use of dome lights?

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Actually not a bad question.

Have you ever walked out of the sun into a house or building that was a little dark and not be able to see anything for a while?  Dome (White) lights on the flight deck can ruin a pilot's night vision, so they are usually turned off after a certain point in preflight - if they are even turned on.  There are, of course, exceptions, some airlines have stipulations and people do things differently, but that's the reasoning behind it.

Share this post


Link to post
Share on other sites

They are (as far as I'm aware) usually on the dim setting for take off in most cases. Some SOPs mention this because if there is an electrical failure of the instrument lights on take off, you still want to be able to see the instruments, obviously. If there are any rules on the matter, they will be in the SOP.

A lot of pilots switch the dome light off at night after take off based on the notion that it will improve their night vision if there is less light in the cockpit, however, it has been shown in a few studies that this is not necessarily a good idea and that it can have some detrimental effects. For one thing, it has been demonstrated that a darker cockpit on a long flight is more likely to induce fatigue than a well lit one will, the difference apparently being quite considerable.

Another issue is, despite the fact that you might have the lights off and be looking out of the window, unless you are actually looking at an object, your eyes will actually focus at a distance which is only approximately one foot outside the glass, unless you actually have an object in sight. This phenomenon has been the cause of some accidents, one of which is still under investigation. Coincidentally, it is an investigation which I'm involved in which is ongoing, so I won't mention that one specifically, but the gist of the problem is, if one pilot is making an instrument approach in poor visibility at night, and is heads down looking at the PFDs, the other pilot is normally looking out of the window to see when the airport is in sight so that he can report that to the pilot on instruments, who will then look up and transition to flying by referencing things visually. However, it has been suggested that switching from the focus of looking at the PFDs to a much greater focal distance suddenly, by looking up and out of the window, can lead to spatial disorientation, so it is now being suggested that the non-flying pilot should only report that the runway is in sight and not that the airport is in sight, because if the flying pilot looks up and initially has a focus only 12 inches outside the window, any lights he or she might see which are not the runway they are aiming for, could disorient them if they are peering through a rain or snow soaked window, or through fog etc, whereas if they see what are unmistakably the approach lights, they are less likely to have that happen. It remains to be seen if that actually becomes a recommendation though.

  • Upvote 1

Share this post


Link to post
Share on other sites

In my experience, the dome light isn't on or it's on extremely dimly, which isn't really simulated in any P3D/XP plane properly I think. But the lights up under the glareshield and MCP will be on along with all the back lighting.

Share this post


Link to post
Share on other sites
7 hours ago, him225 said:

How often and in what phases are cockpit dome lights used in a real airliner? Are these turned on during cruise? My guess is they hinder eye vision outside the window during night and might not be a preference except when aircraft is parked at gate. Are there any restrictions as well on use of dome lights?

 

We have no restrictions (737-800) with regards to it's use. When operating at night on the ground it's on and then it's turned off prior to taxi. In the cruise it's generally on at least dim, mostly so you don't spill your dinner down your front! We then turn it off after the setup and briefing and prior to top of descent.

 

6 hours ago, Chock said:

 

A lot of pilots switch the dome light off at night after take off based on the notion that it will improve their night vision if there is less light in the cockpit, however, it has been shown in a few studies that this is not necessarily a good idea and that it can have some detrimental effects. For one thing, it has been demonstrated that a darker cockpit on a long flight is more likely to induce fatigue than a well lit one will, the difference apparently being quite considerable.

 

An interesting point! Most likely a factor long haul, we don't have any restriction/guidance with regards to flight deck lighting at night. Most guys like to have it off as certainly can affect your vision.

 

For all low visibility approaches (including night) when conducting an Autoland or Monitored Approach the Capt is always PM and looking outside approaching minimums. The F/O flies the approach and will fly the missed approach is not visual or give control to the Captain as soon as he is visual and calls "Land". Dome lighting would be off for all critical stages to improve the chances of seeing some element of the approach lighting system. 

Fly Safe! 

 

  • Upvote 1

Share this post


Link to post
Share on other sites

I can tell you from GA flying, the only time you turn on the dome light is after you have parked the airplane and are looking for all the pens and things you had dropped on the floor during the flight.  I remember when I was a student pilot working on my PPL, I had done a night X-country with my instructor and my good friend who was sitting in the back.  Just before the return trip, my friend was going to take my picture in front of the plane, but my IP told him not to do so because the flash would really screw up my night vision for a while.  Thankfully we took his advice.

That's one of my biggest beefs in FS aircraft, while the night lighting might look pretty, it is often waaay too bright for realistic night flight.  Ideally you want it just bright enough for the gauges to be legible.  Usually you start off with the gauge dimmer a little brighter, then slowly dim it down as you go.  You would be amazed what you can really see at night when your eyes have been given time to adjust.  Manytimes you don't even need a taxi light, you can make out the taxiway centerline just fine.  It's considered common courtesy not to taxi at night with landing or taxi lights on so you don't blind other pilots.  Funnily, I would forget to turn on my car lights at night sometimes because I was used to low light night operations in the plane.

Cheers

TJ

 

  • Upvote 1

Share this post


Link to post
Share on other sites

Interesting, then I can have dim dome lights turned on from before takeoff as it has always been problem to click certain switches in the sim with dome lights off for eg external aircraft lights where the switches go completely dark with only labeling and circle around them visible, causing to miss the switch or turning the adjacent one. Is that a sim issue with lack of correct simulation of ambient lighting or actually goes that dark in the real cockpit as well? if latter does it cause any significant hindrance since in actual cockpit one also feels the knobs which might aid in its placement and position or do pilots turn dome lights on for few seconds to set the cockpit at various transitioning moments of flight?

Share this post


Link to post
Share on other sites

I wonder how often this was used to locate a cigarette, much like I did driving as a teen :laugh:

Share this post


Link to post
Share on other sites

At my company, no specific rules oitside of common sense.

I keep it on at during the preflight until we disconnect from the tug. It doesn't come back on until we park at the gate.this is my personal preference.

Share this post


Link to post
Share on other sites

You may turn them on at night if their is a thunderstorm in the area, the lightening may cause temporary flash blindness so having the dome light on can help reduce that

Share this post


Link to post
Share on other sites

As Alan says, the Human Factors people recommend turning all lighting up as bright as possible in the cruise on the basis that you can't see anything anyway (due to empty field myopia) and having the lights up reduces fatigue. However, as is apparent from this thread, I think most prefer it dark!

Airbus recommend having the dome light on DIM for takeoff as on the A320 series specifically it is powered from the hot battery bus and will therefore continue to operate if you have to shut the engines down in a hurry for an evacuation. This is obviously type-specific though.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now