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I was reading another question earlier when I noticed a story about a 737-700 that landed at M. Graham Clark Downtown Airport in downtown Branson Missouri. The runway is only 3738 ft, long, which is a bit short for that particular kind of aircraft.

Apparently the pilots set the aircraft down hard and immediately did everything in their power to bring the craft to a halt, stopping about 500ft short of the far end of the runway (which, btw, ends in a cliff. Just to heighten the suspense).

I'm sure they had their reason, so I'm not going to question them. I just wanted to use it as a set up for this question:

If you accidentally touch down on a runway that is borderline long enough to stop your aircraft on, how would you determine if you wanted to either stop or just do a touch and go? Is it too late once you've already touched the ground?

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Ah, to set auto-spoilers/brakes for bringing the aircraft to a halt in the least amount of time/distance or not to have the best chance of a successful touch and go? Tough choice isn't it? –  shortstheory Apr 28 at 17:40

3 Answers 3

up vote 22 down vote accepted

In terms of safety, the key mistake was made as soon as the pilot made the decision to land on that runway. The corrective emphasis should be on determining why this mistake was made and taking whatever steps are necessary to prevent that mistake in the future. Especially in transport category airplanes, the crew should always calculate the required landing/rollout distance for the current landing weight, wind, atmospheric (temperature/pressure) and runway surface conditions, and this should be compared against the approach plate / airport diagram / A/FD. In most transport category airplanes this can all be computed by the FMS and it is standard procedure to do this on every single flight.

The question of what to do after the key mistake is still valid, though. I would say it depends on when the pilot recognizes that the runway is too short.

  • If recognized on approach, a simple go around is clearly called for and perfectly safe.

  • Once the wheels touch the ground, the decision gets a lot more complicated. The pilot must choose whether to reject the landing or commit to it. If you recognize it as soon as you touch down, you would probably be able to apply takeoff power and get airborne again safely. Once you've started to brake and decelerate, there will quickly come a point-of-no-return. Since you're starting at high speed, you're using up a lot of runway early in the landing rollout. Also note that in many airplanes it can take a significant amount of time to retract spoilers, stow thrust reversers, and spool the engines back up to takeoff thrust. You'll be consuming a lot of runway during this time. (At a constant 120 knots, you'll use up 2,000 feet of runway in just 10 seconds.)

In my opinion it's far better to commit to a landing. If I'm going to overrun the runway, I'd rather it happen at low speed. If you try to take off again and don't make it, your overrun will be at much higher speed, and destructive energy in a crash is proportional to the square of your ground speed.

So there's a gray area... you could attempt to take off again if you were dead certain you were going to make it. Otherwise, it's most likely best to "cut your losses" and get the airplane as slow as possible when you run out of runway, in order to minimize damage & injury. If you can get it down to, say, 30 or 40 knots, you're likely to escape without any serious injuries (the plane may take a bit of a beating, though, depending on what's beyond the end of the runway). If you do it at 120 knots, all bets are off. And you did mention a specific runway with a cliff at the end; obviously that would have to factor into the decision-making process. It may be that you simply realized your mistake too late and there is nothing you can do about it.

This leads me back to the original point, which is that the key mistake was made as soon as the pilot decided to set up an approach to that runway. The best bet is to make sure that never happens.

EDIT: After reading about the specific incident you referred to, it seems that the pilots simply mistook the airport itself for a different one with a longer runway. So it's not necessarily that they failed to calculate their required landing distance; rather they just landed at the wrong place. This is a different, but equally bad (or worse) mistake, discussed to some extent in the comments below.

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Many airlines have a policy that once reverse thrust has been initiated, you are automatically committed to the landing for exactly the safety reasons you mentioned. –  Bret Copeland Apr 28 at 18:42
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@BretCopeland Some AFM's contain that limitation as well.... –  Lnafziger Apr 28 at 19:05
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Just for extra-scary points, here's what can happen if you don't commit: en.wikipedia.org/wiki/American_Airlines_Flight_625 –  mikeTheLiar Apr 28 at 20:36
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Yeah, the edit is correct. This was a scheduled Southwest Airlines flight. The scheduled runway was plenty long to land the aircraft safely. Unfortunately, they lined up on and landed on the wrong runway at a different airport. A similar incident happened a few months before that with a Boeing Dreamlifter (a modified 747 designed to carry parts for the 787) landing at the wrong airfield in Wichita. The mistake was failing to identify the correct runway, not failing to ensure that the destination runway was long enough. –  reirab Apr 28 at 20:46
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@reirab -- jeez, how do you do that? Nobody noticed? The pilots, the ATC, nobody? Those two airports are 8 miles apart, and the M. Graham Clark Downtown Airport is, as you'd guess, downtown. I hope that alcohol was involved, because I don't like to think that anyone was this dumb sober. –  Malvolio Apr 28 at 22:13

If you accidentally land on a runway chances are you have no idea whether it is long enough or not for either a touch and go or a landing, and you aren't going to be able to figure it out in the time you've got either. For me the answer of what to do depends on what you are flying. If you have a high thrust to weight ratio the safer option may be to set maximum power and try to climb out of it, providing there's no obvious clearance issues. So if I'm in a P-51 I throttle up and set a maximum climb rate speed. Otherwise the best option would be to treat it as a short field scenario and use every means at disposal to remove as much energy from the aircraft as quickly as possible, while warning passengers to brace.

If you survive, go to a mechanic in the local FBO and ask him/her to kick you in the butt as hard as they can for being an idiot.

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"go to a mechanic in the local FBO and ask him/her to kick you in the butt as hard as they can for being an idiot." Usually this service is free of charge, and sometimes you don't even have to ask for it! –  Adam Davis Apr 28 at 20:49
    
Yes, one of the few free things in aviation these days! –  GdD Apr 29 at 7:38

To answer the "title" question (not the detailed questions below):

  • Approach with engine idled (which will mean the plane will be nose-down until you flare)
  • Touchdown at slowest safe speed, hopefully just past the end of the runway
  • Brake hard - really hard
  • Retract flaps
  • Push down the nose
  • Basically you are trying to get as much weight onto the wheels as quickly as possible, which maximizes the effectiveness of your brakes
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Excellent. Is there any difference between how this might work for a jet versus how it might work for a regular piston aircraft or a turboprop? –  Jay Carr Apr 29 at 18:55
    
I would say that in jets you generally have reverse thrust and spoilers to help out. Whether flaps should be retracted would be a good question. –  fooot Apr 29 at 19:11
    
@fooot I mostly ask because the engines aren't nearly as reactive as a prop engine, so...wondered how that might change things. –  Jay Carr Apr 29 at 20:08
    
A jet engine should probably also be at idle, both for minimal thrust and to allow soonest deployment of thrust reversers. –  fooot Apr 29 at 20:35

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