As a passenger with a keen interest in aviation, I'd like to think I'd be eagle-eyed enough to spot a problem that the pilots mightn't be able to see, from where they're sitting (for example, an engine sputtering or ice on the wings).
What things can we look out for, sat in the cabin, that might ultimately save a plane?
This headline made the news this week: Passenger Snaps Photo of Fuel Pouring Out of a Dreamliner's Wing:
The passenger, Ann Kristin Balto from Tromsø, noticed the highly disconcerting leak as the plane was taxiing to the runway—before it actually took off. After alerting the stewardess, the flight was immediately cancelled.
So fuel leaks are one thing you could look out for!
Honestly, as a passenger, you're not really qualified to look for problems. If you're a pilot qualified and with experience in that type then you might see something.
I've had passengers tell my flight attendants that they saw flames coming out of a seam in the engine cowling. It was actually a section of orange rubbery material that was sticking out and flapping in the breeze.
Ice on the wings depends on the airplane too, you're often going to see some ice on the leading edges in icing conditions, and it's normal. To know what's not normal, you have to have experience with that specific type.
There is actually one thing you could probably look for. There are no airplanes that I know of that can safely take off with ice on the top of the wings (behind the leading edges). That would be a legitimate thing to scream about; however, a pilot that would take off in such a case probably shouldn't be a pilot.
You can certainly ask questions about things you see, but don't phrase it such that you think you found a problem.
Window shades are requested to be open for take off and landing by some operators to allow the flight attendants to quickly assess the situation outside when directing an evacuation. It has nothing to do with allowing passengers to look for problems. Not all airlines have this policy either, it's somewhat uncommon, the first thing I do when I sit down at a window in the back is close the window, and it's rare that I'm asked to open it.
Interestingly, the reason why many airlines require window blinds to be raised for take-off and landing is specifically due to the extra visibility it affords passengers and cabin crew in spotting any particular problems for which the pilot and flight crew may not have very good visibility.
Skeptics: Why do we open the window shades during landing and take-off?
Crew and passengers can easily see any external damage, fire or smoke indicating a problem and perhaps bringing it to the attention of flight crew quicker.
There were also reports that it was a passenger who noticed a engine cowling door having been left open after maintenance on a recent British Airways incident flight:
However, although the pilot and flight crew may not be able to see these things directly, you should rest assured that their instrumentation should bring to their attention any engine problems. An engine malfunction or fire would almost certainly become apparent to the flight crew by virtue of warning indications, and loss of power.
That being said, if you ever have cause for concern as a passenger you should bring it to the attention of cabin crew. They will, one would hope, have the skill & experience to know whether to bring it to the attention of the flight crew!
Rogue wing panels flying off and puncturing hoses is the latest thing to make headlines...
Definitely tell the cabin crew if you see anything like that ;)
There are definitely some standard warning signs you can look for:
This will not work in a large commercial airplane but if you are flying a smaller airplane (think Cessna), especially in a crowded airspace, I try to make it into the passenger briefing that if they spot any traffic coming our way, I probably know about it, but they should feel free to call it, including direction and relative height. It never hurts to have the extra pairs of eyes, and passengers seems to enjoy the extra responsibility bestowed upon them.
Beyond that, chances are the pilot is aware of any situation long before the passengers.
Here is some personal experience, though not as spectacular as the other pictures shown here.
It was on a flight from Chicago to Paris CDG, when I noticed somewhere near Spain that there's a loose plate on top of this stabilizer / rear part of pylon of the A340. Being at home, I saw that it was already there at takeoff, as you can see on my picture.
The quite interesting part is that after touchdown, when all air brakes were activated, the plate started to flutter extremely due to the turbulent air flow. At a certain speed, the lift of the air flow was so low, that the plate sunk down into its designated position, and it was as if there has never been something wrong.
I told the cabin crew and got an audience with the pilot. It was difficult to explain the problem to him, as it was not visible any more. He also doubted that I may have seen the flaps...
However... I think this was no serious problem for the aircraft itself, but parts falling off an aircraft on the runway can be a bad thing. Especially at Paris Charles de Gaulle, our destination, they had some very disastrous experience with it.
Cracks in fuselage while boarding. There was flight where a passenger noticed a crack and was too shy to tell cabin crew. The fuselage peeled in flight and at least one person died.
The flight was Aloha 243, a Boeing 737 flying from Hilo to Honolulu that diverted to Kahului, Maui after a very large portion of the top-forward fuselage ripped off due to rapid decompression resulting from metal fatigue cracks. According to the end of Section 1.1 of the NTSB Report (page 5, 2nd paragraph):
After the accident, a passenger stated that as she was boarding the airplane through the jet bridge at Hilo, she observed a longitudinal fuselage crack. The crack was in the upper row of rivets along the S-10L lap joint, about halfway between the cabin door and the edge of the jet bridge hood. She made no mention of the observation to the airline ground personnel or the flight crew.
There was 1 death (a flight attendant who was sucked out of the aircraft) and 65 injuries.
From Section 1.1 of the NTSB Report (page 2, last paragraph):
When the decompression occurred, all the passengers were seated and the seat belt sign was illuminated. The No. 1 flight attendant reportedly was standing at seat row 5. According to passenger observations, the flight attendant was immediately swept out of the cabin through a hole in the left side of the fuselage. The No. 2 flight attendant, standing by row 15/16, was thrown to the floor and sustained minor bruises. She was subsequently able to crawl up and down the aisle to render assistance and calm the passengers. The No. 3 flight attendant, standing at row 2, was struck in the head by debris and thrown to the floor. She suffered serious injuries including a concussion and severe head lacerations.
The remnants of N73711 (the aircraft operating Aloha 243):
Image Source: Wikipedia
told in this way looks like.
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Spanair Flight 5022 crashed during takeoff because flaps were not deployed and the systems involved in warning the pilots about this event, failed. I'm not an expert and I don't know the chances of this event to happen, but if you are about to take off and see no flaps deployed, then that might be a reason for warning the crew.
