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A Boeing 747-400 recently made an emergency landing without the wheels under the right wing:

What's the standard technique for carrying out such a landing?

What might go wrong? Does it require more runway? Is there a significant risk of dragging one wing on the ground?

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    $\begingroup$ While the situation reported was certainly serious. it's worth noting that in the case of the 747, you have both body and wing gear holding up each side of the airplane. Thus it wasn't nearly the problem it would have been in an aicraft with only one landing gear on each side of the airplane, and one of those failed. As a matter of information, had the failure been that of the body gear not extending, that would have been no big deal other than the fact that if the c.g. was greater than 26.6% MAC, the airplane would tip on it's tail once stopped. 26.6% MAC is the location of the wing gear. $\endgroup$
    – Terry
    Dec 30, 2014 at 17:48
  • $\begingroup$ These two accidents, that by strange coincidence both happened in Rome, are more interesting in this regard, since A320 does not have body gear like B747. $\endgroup$
    – Jan Hudec
    Jan 4, 2015 at 16:19

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The techniques vary slightly aircraft to aircraft, and also based on what landing configuration you have. However, the general gist is to hold off the malfunctioning side from the runway for as long as possible, slowing the aircraft in the process, until forced to put it down on the deck. This minimizes the contact between the wings and/or fuselage with the ground.

The single greatest danger with these types of landings is the risk of fire. The friction between the runway surface and the aircraft is tremendous generating an enormous amount of heat. This is particularly problematic when you consider that the fuel is stored in the wings.

Fuel may be pumped to the opposite wing to counter-balance weight and move the fuel away to the fuselage with the highest possibility to have contact with the ground. This technique will shift weight away from the missing wheels and consequently reduce the possibility of fire.

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    $\begingroup$ Might want to add something about dumping the fuel before landing to minimize the risk of an explosion. $\endgroup$
    – codedude
    Dec 30, 2014 at 17:18
  • $\begingroup$ Indeed it appears they dumped fuel from the right wing only, to make it less likely that wing would scrape the ground. $\endgroup$
    – The other other Alan
    Dec 30, 2014 at 21:45
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    $\begingroup$ @jollypianoman Fuel is not dumped to minimise the risk of an explosion. Indeed, the emptier the tank, the higher the risk of explosion. Fuel is dumped to reduce weight and, as in this case, to make the CoG advantageous to whatever situation you are in. An explosion is highly unlikely anyway and there is more risk of fire in landing an overweight aircraft. $\endgroup$
    – Simon
    Dec 30, 2014 at 22:48
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    $\begingroup$ It should probably be noted that the wing itself, in the specific case of a 747 but for all aircraft with jet engines below the wings, can't really touch the ground. The first thing to touch the ground would be the engine nacelle. What a landing on a nacelle looks like can be seen here: youtube.com/watch?v=iPo1mGgK5S4 (YouTube, LOT B767 landing) Since both the engine housings and the engine mounts are very strong for safety reasons, this works somewhat well (at least in this case). $\endgroup$
    – JulianHzg
    Dec 30, 2014 at 23:33
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    $\begingroup$ @paul, they're centerline enough that you don't need to keep the low wing flying to keep it off the ground. $\endgroup$
    – Mark
    Dec 31, 2014 at 8:21

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