Posts: 206
Joined: Tue Dec 12, 2000 10:35 pm

5 Questions....

Wed May 23, 2001 8:44 am

Sorry if the answers to these questions are common knowledge. Quick search did not reveal answers....

1) Why dim the cabin lights during takeoff?

2) Are there any regulations regarding when the cockpit door is to be closed at the start of a flight?. Most times I see it closed before or shortly after pushback. I have been on one flight recently where it wasn't closed until moments before starting down the runway. On another flight, it was open until we were got to the end of the taxiway (before we made a 180° turn to line up on the runway). In both instances, pilots and FA were conversing until door was shut. It seems as though the pilots should be more focused on the takeoff and less on the FA....

3) Why does the CRJ use winglets? I understood wiglets to aid in fuel ecomomy during long distance flights. There must be another or other reason(s) since CRJ flights are generally short.

4) Is it physically possible for someone to open an emergency exit during flight? At any altitude?

5) Is there any easy way to figure out what routes Delta uses the L-1011 on? I realize that equipment can change at the last minute, but I would like to try to schedule a trip on a TriStar before they are all gone...

Posts: 4713
Joined: Mon Mar 01, 2004 4:46 am

RE: 5 Questions....

Wed May 23, 2001 8:56 am

2) The flight crew is supposed to have a "sterile cockpit" at certain times of the flight like takeoff, landing, and descent. At this time the cabin door must be closed, no PA announcements by the pilots and no visitors in the cockpit. But the door has to be closed for the whole flight, I think from throttle up (for TO until they get off of the runway at the destination.

3) Winglets help prevent wingtip vortices, (when the high and low pressure on both sides of the wing meet) someone else could tell you more, I don't think they are there for fuel economy though.

5) I work for DL and I'm almost positive all of the L-1011 flights are to Florida and Hawaii. Try ATL-MCO,TPA,MIA,FLL.
Pan Am:The World's Most Experienced Airline - P(oor) S(ailor's) A(irline): San Diego's Hometown Airline-Catch Our Smile!
Posts: 1044
Joined: Wed Feb 14, 2001 4:15 am

RE: 5 Questions....

Wed May 23, 2001 8:59 am

1) so that pax and crew do not have to adjust to total lights-out situation in the case of an emergency.

Posts: 1044
Joined: Wed Feb 14, 2001 4:15 am

RE: 5 Questions....

Wed May 23, 2001 9:01 am

4) If the door is a plug type it is kept there by the pressure within the a/c - several psi at altitude - multiply that by the area of the door and the total pounds pressure is enormous.

Are there any a/c that do not use the plug type ?

Posts: 2645
Joined: Mon May 24, 1999 5:53 am

RE: 5 Questions....

Wed May 23, 2001 4:00 pm

1. So that eyes are adjusted to the outside light in case of a crash on t/o or landing.

BTW, FAA rules (and others) do NOT prevent authorised cockpit visits at t/o and landing
Posts: 491
Joined: Mon Nov 01, 1999 4:34 pm

RE: 5 Questions....

Wed May 23, 2001 7:02 pm

Lights out on take off and landing! Its different between airlines, Qantas have there lights on for take off and landing. Lights out just makes it possible for people to see out the window, as simple as it sounds.

In regards to winglets, they help reduce the strength and size of wingtip vortices, as was rightly said, but wingtip vortices are a form of drag, so by eliminating this, it means thrust does not have to be as great, hence less fuel consumption. The answer to many peoples question, why dont they put winglets on every aerofoil is, well in many cases, they just dont make a difference. And to some extent may even produce a stronger vortex.

As for the cockpit door, I think you find that its closed when its not getting used. I couldnt think of any regs that regard when the cockpit door must be shut. Although, t/o and ldg would be exceptions.

As for the plug type emergency exits, well as long as you un arm the switch and you have a strong enough arms and even legs, well its possible. As soon as you can get that initial bit of air out, it will become quite easy.

Ive seen some pics of new boeing a/c, not sure which ones where the doors open outward on a horizontal hinge. I would imagine that wouldnt be plugged for that to be possible.

Anyway, I hope some of that information helps!

Posts: 6199
Joined: Wed May 23, 2001 12:58 pm

RE: 5 Questions....

Thu May 24, 2001 2:39 am

Question 4) If a door is 7 ft by 4 ft and cabin pressurization is only 2 PSI, it would be the equivalant to lifting 8064 pounds. No it cannot be done. An small example ? Take a good magnet, say two pounds, and stick it to a piece of steel. Then try to pull it off. Almost impossible.
The day you stop learning is the day you should die.
Posts: 112
Joined: Tue Nov 16, 1999 11:14 am

RE: 5 Questions....

Thu May 24, 2001 4:46 am


If aircraft (or part of it) is not pressurized, I mean, the door can of course be open, but otherwise, I seriously doubt it.
However, regarding the plug type door, not all aircraft use it. Just as an example, we could mention the incident involving a Turkish Airlines DC10 north of Paris a few years back. Cargo 5 door, which wasn't plug type, just kind of standard (but how complex) lock. Captain and instruments thought it was closed properly. It wasn't. Depressurization. Back of the aircraft collapsed, a few rows felt down from FLT110 I think, no survivors.

F. Meunier
lmml 14/32
Posts: 2358
Joined: Tue Jan 30, 2001 2:27 am

RE: 5 Questions....

Thu May 24, 2001 4:58 am

1.) Lights are dimmed on night flights for the occupants' eyes to adjust to night time in case of emergency.

2.) JAR-OPS state that cockpit door is to be closed at all times from push back.

3.) Winglets' primary function is to reduce fuel consumption by a small percentage. The vortices theory is a secondary benefit.

4.) No body can open a door of a pressurised aircraft.

5.) Have not the slightest idea
Posts: 491
Joined: Mon Nov 01, 1999 4:34 pm

RE: 5 Questions....

Sat May 26, 2001 10:28 am

LMML 14/32
It reduces fuel consumption by reducing drag. If anything, fuel consumption is the secondary benefit.

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