How do larger aircraft compensate for reduced visibility from the cockpit, e.g. less visibility of the rear of the aircraft?

Question

In smaller planes, pilots has apparently great visibility in front, on the sides and a good portion of the rear of the plane. But as the plane's size is increased, the visibility is also reduced. One obvious factor is height of the cockpit from ground, but it appears (from pictures) that pilots of bigger Boeing/Airbus planes have too many blind spots. However, I did notice that some bigger planes have a camera behind the nose gear to ease in taxiing etc.

So the question is that how do pilots compensate for this lesser visibility? Do they always need external help (e.g. ground crew)? Is there some sophisticated technology helping them? I am sure they cannot just raise or lower a wing or some other maneuver to check nearby traffic.

Answer 1

Appearances can be deceiving. The view "behind" a Piper Cherokee looks something like the image below: no rear window so you can't see what's behind you, but that really doesn't matter since there's no way to go "backward" in this aircraft using the flight controls.

Visibility aside, ground handling is often a a complex production, particularly for larger aircraft or when you have a lot of aircraft in proximity to each other or obstacles.

Moving small aircraft around typically requires at least 3 people. When you're moving forward you will have the person operating the tug and two "wing walkers" who stand a few feet off the wingtips and walk along to make sure the wings aren't going to hit anything. When pushing an aircraft back in a tightly packed hangar there's sometimes a fourth person walking ahead of the tail to make sure you don't back the plane into something.
Since there's not usually much for the pilot to do inside the plane at this point, they usually serve as one of the walkers.

Larger aircraft observe similar procedures, but for push-backs or power-backs it's known that the area behind the aircraft is clear (this is usually coordinated over the radio), and as long as the tug driver or pilot keeps the nosewheel on the appropriate pavement markings there will be wingtip clearance.

Line personnel are also often stationed to guide aircraft to and from parking in close quarters where positioning is critical (e.g. when pulling an airliner up to a gate, or parking a small aircraft on a busy ramp).

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The other half of the picture is taxiing under your own power and control.

When taxiing, it's generally assumed that the pilot knows their aircraft's dimensions and will avoid hitting things. This usually works out well, but that is not always the case.

Airport taxiways are marked so an aircraft with a specific maximum wingspan will be clear of any obstacles while taxiing along the centerline, and as you're generally only going forward that's where visibility is most important (you can assume if the area your wingtip was going to hit was clear 15 seconds ago when you last saw it and nothing was heading into that area it's still clear now, and you're relying on the pilot of the aircraft behind you to be paying attention and not taxi into your tail).

Answer 2

Large planes generally have quite good visibility. In a document A319/A320/A321 Flight Deck and Systems Briefing for Pilots (can be found in many places on the net, e.g. on slideshare as presentation), or page 16 Airbus shows following diagram of visibility from cockpit:

20 degrees below horizon straight ahead is probably better than most single-engine GA aircraft with large engine cowling in front of the cockpit.

Answer 3

Small aircraft are generally under VFR rules, where they need to have that visibility to look out for other traffic. Larger aircraft usually operate under IFR rules, where (as ratchet pointed out) ATC helps to separate traffic, and TCAS will help as well. At the high speeds at which they fly, visual separation is less useful, anyway.

Also, especially when you start travelling faster, what matters most is what's in front. If everyone makes sure they don't run over someone, you shouldn't have to worry about getting hit from behind.

When at the gate, most aircraft (even the smaller ones) will have a person guiding them in, and during pushback the tug driver has a better view and wing walkers make sure the wing tips clear.

When taxiing, pilots will get a feel for how to control the aircraft from training and experience. Especially in large airplanes, they can be sitting significantly forward of the front landing gear, making it a bit disorienting to maneuver if you are not used to that.

However, incidents happen. You may recall recent incidents where planes have clipped each other while taxiing, such as this one at LAX. Because of these incidents, the NTSB has recommended that improvements such as cameras would help avoid these situations.

The A380 has a camera on its tail that helps the pilots stay aware, but it is unique in this regard (though it doesn't appear to have a wide enough view to include wingtips).

Answer 4

On the ground, pilots of commercial airliners taxi without the help of ground crews except for entering and departing the gate area. Once out on the taxiways they follow the painted line. Keeping the nosewheel on the line pretty much guarantees that there is enough clearance for the plane including the wingspan.

Answer 5

More of a historical anecdote, but the British VC-10 had a periscope (!) with no less than four different mounting locations- two in aft cabin (for viewing each side the tailplane), the cockpit (originally for the sextant) and the electronic bay looking downwards to inspect the landing gear. It appears to be more for technical reasons rather than operational ones.

^{Photo: J. Hieminga}

^{"Photo BOAC via C. Messenger"}

Normally the periscope will be stored in its box somewhere in the back of the aircraft. In A4O-AB, the Sultan of Oman's aircraft, this box is kept in the aft galley. The periscope itself is about two and a half feet in length, and is a pretty sturdy piece of ironmongery. There are two mountings for the periscope in the roof of the fuselage, which are similar in design, both to be found just in front of the rearmost toilets in the aircraft. These can be revealed by undoing two quick-release catches on one of two small triangular panels in the roof. This provides the sight below.

In its installed position the periscope can be rotated 360 degrees, and the control on the side tilts the mirror at the top about 60 degrees up and down. All together you can look all the way around the aircraft, except for straight up at the sky (but there shouldn't be much to look at up there anyway). By switching from one mounting to the other both sides of the fin can be viewed. From the lefthand mounting, looking to the right wingtip will have you looking at the base of the fin as the periscope sticks up right next to it.

This same periscope can also be mounted in two other locations. The first of these is in the cockpit roof. The mounting installed here was meant originally for use with a periscopic sextant, but will also take the periscope. During BOAC crew training flights where Dutch Roll characteristics were demonstrated trainees were sometimes given a chance to view the back end of the plane from here to see the effects. The second location is located in the bottom of the fuselage and was included to enable the crew to check the status of the landing gear if any uncertainty about its position was present amongst the crew. It consisted of an opening in the electronics bay access hatch located underneath the fuselage. Unlike the others there was no pressure shutter to cover this opening - it was just a plug that could be removed and replaced with the periscope - since it would generally only be used at lower altitudes where the pressure differential would be lower. Still it has been confirmed to me by an ex-BOAC First Officer that the plug could be removed when flying at 39000 feet, although this needed quite a pull and the result was quite noisy!

Source of the quote and pictures: VC10.net